JP2012122763A - Method and system for determining lens quality - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and system to easily determine a lens quality.SOLUTION: The method and system includes steps of: an actual measurement step (step S1) to measure a center thickness of a lens; a measurement step (step S2) to measure a position of a reference mirror at which the intensity of the interference light is a maximum by a low-coherence interference method; an estimation step (step S3) to estimate the center thickness of the lens using the refraction factor of a glass material, a material of the lens after calculating an optical path length difference based on the position of the reference mirror measured in the step S2; and a determination step (step S4) to determine whether the estimated center thickness of the lens in the step S3 is within the preset range based on the measured center thickness of the lens in the step S1.

Description

  The present invention relates to a lens quality determination method and a lens quality determination system.

  There are a wide variety of glass materials used as materials for optical elements such as lenses, and it is difficult to distinguish the types of glass materials (hereinafter referred to as “glass types”) only by their appearance. For this reason, when a lens having a similar shape and a different glass type is mixed, it is generally performed to determine the glass type by measuring the refractive index of the lens.

  Conventionally, as a method for specifying the refractive index of a lens, it is disclosed that the refractive index is determined by a refractive index measurement method using a Fizeau interferometer (see Patent Document 1), a minimum deflection angle method, an autocollimation method, a critical angle method, or the like. (See Non-Patent Document 1).

JP 2009-133727 A

Edited by Goro Kuwabara, “Optical Technology”, Kyoritsu Publishing, September 10, 1984, p.7, p.311

  However, the conventional refractive index measurement method described above has a problem that a polished surface is required for measurement by any of the methods, and it takes a lot of time and labor to discriminate the quality of the glass type of the lens. .

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a lens quality determination method and a lens quality determination system capable of easily determining the quality of a lens.

  In order to solve the above-described problems and achieve the object, the lens quality determination method of the present invention is a lens quality determination method for determining a lens quality using light emitted from a low-coherence light source. An actual measurement step for actually measuring, and dividing the light from the low-coherence light source into reference light and measurement light, irradiating the measurement light to the first surface or the second surface of the lens and irradiating the reference light to the reference mirror A measuring step for measuring the position of the reference mirror at which the intensity of the interference light between the measurement light reflected by the first surface and the reference light and the interference light between the measurement light reflected by the second surface and the reference light is maximized; Calculating an optical path length difference based on the position of the reference mirror measured in the measuring step, and estimating a center thickness of the lens using a refractive index of a glass material that is a material of the lens; and Center thickness of the lens estimated in step, characterized in that it comprises a determination step of determining whether the center is within the range set based on the thickness of the lens was measured by the actual measurement step.

  In the lens quality determination method of the present invention, in the above invention, when it is determined in the determination step that the center thickness of the lens estimated in the estimation step is out of a setting range, the type of the glass material of the lens is different. It is characterized by including the alerting | reporting step which alert | reports.

  The lens quality determination method of the present invention is a lens quality determination method for determining the quality of a lens using light emitted from a low coherence light source. From the measurement step of actually measuring the center thickness of the lens, the low coherence light source Is divided into reference light and measurement light, the measurement light is applied to the first surface or the second surface of the lens, the reference light is applied to the reference mirror, and the measurement light and the reference light reflected by the first surface are reflected. Measuring step for measuring the position of the reference mirror where the intensity of the interference light between the measuring light reflected by the second surface and the measuring light reflected by the second surface and the reference light is maximized, and the position of the reference mirror measured in the measuring step. An optical path length difference is calculated based on the refractive index calculation step of calculating the refractive index of the lens using the lens center thickness of the lens actually measured in the measurement step, and the refractive index calculation step. Refractive index of the lens out is characterized in that it comprises a determination step of determining whether it is within the predetermined range.

  In the lens quality determination method of the present invention, in the above invention, when the determination step determines that the refractive index of the lens calculated in the calculation step is outside a predetermined range, the type of the glass material of the lens is different. It is characterized by including the alerting | reporting step which alert | reports.

  In the lens quality judgment method according to the present invention, in the above invention, the actual measurement step is two sensor heads each of two non-contact type length meters each having their respective measurement axes aligned with each other and facing each other. An arrangement step in which the optical center of the lens is exposed at least between the two arranged sensor heads, and the lens is arranged such that the optical axis of the lens to be tested coincides with the measurement axis; A measuring step of measuring a distance from the two sensor heads to the lens by each of the non-contact type length meters, and a sum of the distances to the lenses measured by the two non-contact type length meters. And calculating a lens center thickness of the lens by subtracting it from the distance between the two sensor heads.

  In the lens quality determination method according to the present invention as set forth in the invention described above, the actual measurement step includes a second measurement step of measuring a distance between the two sensor heads before the calculation step.

  In the lens quality judgment method according to the present invention, in the above invention, the actual measurement step is two sensor heads each of two non-contact type length meters each having their respective measurement axes aligned with each other and facing each other. A master lens that exposes at least the optical center of a master lens having a known lens center thickness between the two sensor heads that are arranged, and arranges the master lens so that the optical axis of the master lens coincides with the measurement axis An arrangement step; a master lens measurement step for measuring a distance from the two sensor heads to the master lens by each of the two non-contact type length meters; and an optical of the lens between the two sensor heads. The lens is arranged with at least the center exposed and with the optical axis of the lens coincident with the measurement axis. A lens placement step; a lens measurement step for measuring the distance from the sensor head to the lens by each of the two non-contact type length meters; and a distance to the master lens measured in the master lens measurement step. Calculating the difference between the sum and the sum of the distances to the lens measured in the lens measurement step, and calculating the lens center thickness of the lens from the difference and the lens center thickness of the master lens. It is characterized by.

  The lens quality determination system of the present invention is a lens quality determination system that determines the quality of a lens using light emitted from a low-coherence light source, a lens center thickness measuring device that measures the center thickness of the lens, Measurement by dividing the light from the coherence light source into reference light and measurement light, irradiating the measurement light on the first surface or the second surface of the lens, irradiating the reference light on the reference mirror, and reflecting on the first surface Measuring means for measuring the position of the reference mirror where the intensity of the interference light between the interference light between the light and the reference light and the interference light between the measurement light reflected by the second surface and the reference light is maximized, and the reference measured by the measurement means An optical path length difference is calculated based on a mirror position, and an estimation means for estimating a center thickness of the lens using a refractive index of a glass material that is a material of the lens, and a center thickness of the lens estimated by the estimation means is A determination unit that determines whether or not the lens center thickness measured by the lens center thickness measuring instrument is within a range set based on the center thickness of the lens, and the determination unit sets the center thickness of the lens estimated by the estimation unit And a notifying unit for notifying that the type of glass material of the lens to be tested is different when it is determined that the lens is out of the range.

  The lens quality determination system of the present invention is a lens quality determination system that determines the quality of a lens using light emitted from a low-coherence light source, a lens center thickness measuring device that measures the center thickness of the lens, Measurement by dividing the light from the coherence light source into reference light and measurement light, irradiating the measurement light on the first surface or the second surface of the lens, irradiating the reference light on the reference mirror, and reflecting on the first surface Measuring means for measuring the position of the reference mirror where the intensity of the interference light between the interference light between the light and the reference light and the interference light between the measurement light reflected by the second surface and the reference light is maximized, and the reference measured by the measurement means The optical path length difference is calculated based on the mirror position, and the refractive index calculation means for calculating the refractive index of the lens using the lens center thickness actually measured by the lens center thickness measuring instrument, and the refractive index calculation means. A determining unit that determines whether or not the refractive index of the lens is within a predetermined range; and the determination unit determines that the refractive index of the lens calculated by the refractive index calculating unit is out of the predetermined range. And an informing means for informing that the type of the glass material of the analyzing lens is different.

  In the lens quality determination system according to the present invention, the lens center thickness measuring instrument may include two non-contact type length meters having a sensor head for distance measurement, and the two non-contact type length meters. A length measuring device support unit that supports each sensor head so that the measurement axes of the sensor heads are aligned with each other, and is provided between the sensor heads, and exposes at least the optical center of the lens to be measured. And a lens holding unit for holding the lens to be tested with the optical axis of the lens to be matched with the measurement axis.

  According to the present invention, there is an effect that the quality of the glass type or the like of the test lens can be determined very easily without processing the test lens.

FIG. 1 is a schematic diagram illustrating a lens quality determination system according to the first embodiment. FIG. 2 is a schematic diagram showing a configuration of a low coherence interferometer used in the lens quality determination system shown in FIG. FIG. 3 is a schematic diagram showing the configuration of the lens center thickness measuring instrument used in the first embodiment. FIG. 4 is a flowchart of the lens quality determination process according to the first embodiment. FIG. 5 is a flowchart showing the procedure of the center thickness measurement process of the lens to be examined in FIG. FIG. 6 is a flowchart showing the procedure of the interference light measurement process of FIG. FIG. 7 is a schematic diagram illustrating a configuration of a lens center thickness measuring instrument used in the lens quality determination system according to the first modification of the first embodiment. FIG. 8 is a schematic diagram illustrating a configuration of a lens center thickness measuring instrument used in the lens quality determination system according to the second modification of the first embodiment. FIG. 9 is a flowchart showing another example of the center thickness measuring process of the lens to be tested when the lens center thickness measuring device of FIG. 8 is used. FIG. 10 is a schematic diagram illustrating a configuration of a lens center thickness measuring instrument used in the lens quality determination system according to the third modification of the first embodiment. FIG. 11 is a schematic diagram illustrating a configuration of a lens center thickness measuring instrument used in the lens quality determination method according to the fourth modification of the first embodiment. FIG. 12 is a schematic diagram illustrating a configuration of a lens center thickness measuring instrument used in the lens quality determination method according to the fifth modification of the first embodiment. FIG. 13 is a schematic diagram illustrating a lens quality determination system according to the second embodiment. FIG. 14 is a flowchart of a lens quality determination process according to the second embodiment.

  Hereinafter, embodiments of a lens quality determination method and a lens quality determination system of the present invention will be described in detail with reference to the drawings. The lens quality determination method and the lens quality determination system of the present invention are not limited to the following forms.

(Embodiment 1)
A lens quality determination system according to a first exemplary embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram illustrating a lens quality determination system 100 according to the first embodiment.

  The lens quality determination system 100 according to the first embodiment includes a low coherence interferometer 10 that observes interference light using a low coherence light source, and a lens center thickness measuring device that measures the center thickness of a lens to be tested (glass lens). 50, and a measurement processing unit 30 that determines the quality of the test lens based on the results obtained by the low coherence interferometer 10 and the test lens center thickness measuring instrument 50.

  FIG. 2 is a schematic diagram showing the configuration of the low coherence interferometer 10 used in the lens quality determination system 100 shown in FIG. The low coherence interferometer 10 divides the light emitted from the low coherence light source 11 into reference light and measurement light by the polarization beam splitter 14, and the measurement light is first surface (La) or second surface of the lens L1 to be measured. (Lb) is irradiated with reference light to the reference mirror 16, and interference light Ia is generated by superimposing the measurement light reflected on the first surface and the reference light, and the measurement light reflected on the second surface and the reference light. Observing the interference light Ib by the superimposing with the image sensor 21, the position P1 of the reference mirror 16 where the intensity of the interference light is maximum (the position where the intensity of the interference light Ia by the measurement light reflected by the first surface is maximum) and P2 (a position where the intensity of the interference light Ib by the measurement light reflected by the second surface is maximum) is measured. At the time of measurement, the test lens L1 is installed so that its optical axis Lx coincides with the illumination optical axis MA3.

  As the low coherence light source 11, a light source having a short coherence length, for example, ASE (Amplified Spontaneous Emission), LED (Light Emitting Diode), SLD (Super Luminescent Diode), or the like is used. The light beam having a short coherence distance emitted from the low-coherence light source 11 is converted into parallel light by the collimator lens 12 and becomes linearly polarized light by passing through the polarizing plate 13. The light beam that has been linearly polarized by the polarizing plate 13 is split into p-polarized light and s-polarized light by a polarizing beam splitter 14 that is a light beam splitting means.

  The p-polarized light split by the polarizing beam splitter 14 passes through the polarizing beam splitter 14 as it is as reference light. The reference light which is p-polarized light passes through the λ / 4 plate 15 and becomes circularly-polarized light and is irradiated on the reference mirror 16. The irradiated reference light is reflected by the reference mirror 16, passes through the λ / 4 plate 15 again, becomes s-polarized light, and enters the polarization beam splitter 14. The s-polarized reference light is reflected by the polarization beam splitter 14, passes through the polarizing plate 20, and enters the image sensor 21 that is an imaging device.

  The s-polarized light split by the polarizing beam splitter 14 is reflected by the polarizing beam splitter 14 and becomes measurement light. The measurement light that is s-polarized light becomes circularly-polarized light by passing through the λ / 4 plate 18, enters the collimator lens 19, is collected, and then enters the test lens L <b> 1. The collimator lens 19 is a shaping lens that can be moved and adjusted in the direction of the optical axis Lx of the test lens L1, and is centered on the curvature of the first surface (upper surface: La) or the second surface (lower surface: Lb) of the test lens L1. Its position is adjusted so that it is incident. The measurement light that is incident and reflected on the first surface (La) or the second surface (Lb) of the lens L1 to be measured passes through the collimator lens 19 and the λ / 4 plate 18 again to become p-polarized light, and is polarized beam splitter 14. Is incident on. The p-polarized measurement light passes through the polarization beam splitter 14 and is superimposed on the above-described reference light. The interference light between the reference light and the measurement light passes through the polarizing plate 20 and enters the image sensor 21 that is an image sensor.

  The image sensor 21 images the interference patterns of the interference lights Ia and Ib of the reference light and the measurement light. The image sensor 21 transmits the imaging signal to the image processing unit 31 of the measurement processing unit 1. The image processing unit 31 performs image processing on the transmitted imaging signal, sets an interference light acquisition area, and measures the interference light intensity. The intensity of the interference light Ia and Ib of the measurement light and the reference light varies depending on the position of the reference mirror 16 where the reference light is reflected. In the present invention, the interference light intensity is measured by the image sensor 21 and the image processing unit 31 while operating the position of the reference mirror 16, and the position of the reference mirror 16 at which the intensity of the interference lights Ia and Ib has the maximum value is measured. 17 is measured.

  The measurement of the interference light intensity is performed with the position P1 of the reference mirror 16 where the measurement light is incident on the first surface (La) of the lens L1 and the intensity of the reflected measurement light and the reference light interference light Ia is maximized. Then, the measurement light is incident on the second surface (Lb) of the lens L1, and the reflected measurement light and the position P2 of the reference mirror 16 where the intensity of the interference light Ib of the reference light is maximum are measured.

  The difference between the position P1 (first surface) and P2 (second surface) of the reference mirror 16 (the interference light Ia contrast of the first surface (La) of the lens L1 to be measured and the interference light Ib contrast of the second surface (Lb)). Is the optical path length difference l of the lens L1. Since the optical path length difference l is the product of the lens thickness and the lens refractive index, it is assumed that the test lens L1 is a lens L formed from a desired glass type, and the refractive index n of this glass material is used. The lens center thickness d of the detecting lens L1 is estimated. The estimation unit 33 estimates the value calculated by dividing the optical path length difference l by the refractive index n with respect to the light source wavelength of the specific glass type as the lens center thickness d of the test lens L1.

  The measurement processing unit 30 includes an image processing unit 31 that performs image processing on the imaging signal transmitted from the image sensor 21, a measurement unit 32 that calculates a center thickness d1 of the lens L1 to be measured by a lens center thickness measuring instrument 50 described later, An estimation unit 33 that estimates the center thickness d of the test lens L1 and the center thickness d of the test lens L1 estimated by the estimation unit 33 become the center thickness d1 of the test lens L1 measured by the lens center thickness measuring instrument 50. On the other hand, a determination unit 34 that determines whether or not it is within a predetermined range, an interference pattern that is observed with the low coherence interferometer 10, a display unit 35 that displays a determination result of the determination unit 34, and a control that controls each mechanism. Part 36.

  Next, the lens center thickness measuring instrument 50 that measures the center thickness d1 of the lens L1 to be measured will be described. FIG. 3 is a schematic diagram showing the configuration of the lens center thickness measuring instrument 50 used in the first embodiment.

  The lens center thickness measuring instrument 50 measures the distance to the test lens L1 by each of the two non-contact type length meters 51a and 51b arranged on both sides in the thickness direction of the test lens L1. The lens center thickness measuring instrument 50 supports each of the non-contact type length meters 51a and 51b in addition to the two non-contact type length meters 51a and 51b, thereby supporting each of the non-contact type length meters 51a and 51b. A length measuring device support portion 55 that supports the sensor heads 53a and 53b of the contact type length measuring devices 51a and 51b, and a lens holding portion 60 provided between the sensor heads 53a and 53b are provided.

  The lens center thickness is measured by measuring the distance D between the sensor head 53a of the non-contact type length meter 51a and the sensor head 53b of the non-contact type length meter 51b and the measurement results of the non-contact type length meters 51a and 51b. It is calculated using. A method for measuring the lens center thickness of the test lens L1 using the lens center thickness measuring device 50 will be described.

  The non-contact type length gauges 51a and 51b measure the distance to the object without contacting the object, and have length measurement main bodies 52a and 52b and sensor heads 53a and 53b. As the non-contact type length meters 51a and 51b, an optical length meter using a laser beam or the like as a measurement light or an ultrasonic length meter can be used. When an antireflection film or the like using a conductive material is provided on the lens L1, an eddy current type length meter can be used as the non-contact type length meters 51a and 51b. In the non-contact type length gauges 51a and 51b, the sensor heads 53a and 53b are incorporated in the length gauge main bodies 52a and 52b. However, the sensor head is connected to the length meter main body by an optical fiber, a cable, or the like. It is also possible to use a non-contact type length meter drawn out to the outside.

  The length meter support portion 55 includes an upper support portion 56, a lower support portion 57, and a connecting portion 58 that connects the upper support portion 56 and the lower support portion 57. The upper support portion 56 is connected to the connecting portion 58. The lower support portion 57 projects horizontally from the lower end side of the connecting portion 58. The length meter support portion 55 makes the sensor heads 53a and 53b of the non-contact type length meters 51a and 51b face each other, and makes the measurement axis MA1 of the sensor head 53a and the measurement axis MA2 of the sensor head 53b coincide with each other. Thus, the sensor heads 53a and 53b are supported.

  For example, on the manufacturer side of the lens center thickness measuring instrument 50, the measuring axes MA1 and MA2 coincide with each other and the sensor heads 53a and 53b are attached to the length measuring meter main body 52a and 52b. The distance D is set to a fixed value.

  The lens holding unit 60 is for holding the test lens L1 between the sensor heads 53a and 53b by making the optical axis Lx of the test lens L1 coincide with the measurement axes MA1 and MA2 of the sensor heads 53a and 53b. The lens support member 60 in which the test lens L1 is disposed so as to expose at least the optical centers Lc and Ld on the lens surfaces La and Lb, and a support portion that holds the lens support member 60 between the sensor heads 53a and 53b ( (Not shown). In the first embodiment, the test lens L1 is supported by the lens support member 61 with the optical centers Lc and Ld on the lens surfaces La and Lb and the periphery thereof exposed.

  The lens support member 61 is composed of two flat plate members 61a and 61b that are spaced apart from each other. Each flat plate member 61a, 61b has a support surface having a shape corresponding to the curved surface shape of one lens surface Lb of the test lens L1. The test lens L1 is disposed on the lens support member 61 with the lens surface Lb in surface contact with the support surface. For example, each of the lens support member 61 and the test lens L1 is previously provided with an alignment mark so that the optical axis Lx of the test lens L1 can coincide with the measurement axes MA1 and MA2 of the sensor heads 53a and 53b. The

  The measuring unit 32 of the measurement processing unit 30 measures the distance D between the sensor head 53a of the non-contact type length meter 51a and the sensor head 53b of the non-contact type length meter 51b, and the measurement of each of the non-contact type length meters 51a and 51b. From the result, the lens center thickness d1 of the test lens L1 is calculated.

  Hereinafter, the quality determination process of the test lens L1 in the lens quality determination system 100 according to the first embodiment will be described with reference to FIGS. FIG. 4 is a flowchart of the lens quality determination process according to the first embodiment.

  In the lens quality determination system 100 according to the first embodiment, first, the center thickness measurement process of the test lens L1 is performed (step S1).

  FIG. 5 is a flowchart showing the procedure of the center thickness measurement process of the lens L1 in FIG. In the process of measuring the center thickness of the test lens L1, first, the test lens L1 is disposed between the sensor heads 53a and 53b with the optical axis Lx of the test lens L1 aligned with the measurement axes MA1 and MA2. Specifically, the optical centers Lc and Ld on the lens surfaces La and Lb of the lens L1 and the periphery thereof are exposed, and the optical axis Lx of the lens L1 is aligned with the measurement axes MA1 and MA2. The test lens L1 is disposed on the lens support member 61 of the lens holding unit 60 (step S11).

  Subsequently, the distances from the sensor heads 53a, 53b to the lens L1 to be measured are measured by the non-contact type length meters 51a, 51b (step S12). Specifically, the distance to the lens surfaces La and Lb is measured. The non-contact type length meter 51a measures the distance from the sensor head 53a to the lens surface La, and the non-contact type length meter 51b measures the distance from the sensor head 53b to the lens surface Lb.

  The measuring unit 32 subtracts the sum of the distances to the test lens L1 measured by the non-contact type length meters 51a and 51b from the distance D between the sensor heads 53a and 53b to obtain the lens center thickness d1 of the test lens L1. (Step S13).

  Thereafter, the test lens L1 is removed from the lens holding unit 60 (step S14), and the center thickness measurement process of the test lens L1 is terminated.

  After the center thickness measurement processing of the test lens L1 in step S1, measurement processing of interference light between the measurement light reflected by the test lens L1 and the reference light is performed using the low coherence interference method (step S2).

  FIG. 6 is a flowchart showing the procedure of the interference light measurement process of FIG. In the interference light measurement process, first, the optical axis Lx of the lens L1 to be examined is made to coincide with the illumination optical axis MA3 and placed on a lens support (not shown) (step S21).

  After disposing the test lens L1, the position of the collimator lens 19 is adjusted so that the measurement light is incident on the center of curvature of the first surface (La) of the test lens L1 (step S22).

  After adjusting the position of the collimator lens 19, the light emitted from the low coherence light source 11 is divided into reference light and measurement light by the polarization beam splitter 14, and the measurement light is applied to the first surface (La) of the lens L1 to be measured. The reference light is irradiated onto the reference mirror 16 and the interference light Ia between the measurement light reflected by the first surface and the reference light reflected by the reference mirror 16 is observed by the image sensor 21, and the intensity of the interference light Ia is increased. The position P1 of the reference mirror 16 that is the maximum is measured by the length measuring machine 17 (step S23).

  The position of the collimator lens 19 so that the measurement light is incident on the center of curvature of the second surface (Lb) of the test lens L1 after the observation of the interference light of the reflected light from the first surface (La) of the test lens L1 is completed. Is adjusted (step S24).

  After adjusting the position of the collimator lens 19, the light emitted from the low coherence light source 11 is divided into reference light and measurement light by the polarization beam splitter 14, and the measurement light is applied to the second surface (Lb) of the lens L1 to be measured. The reference light is applied to the reference mirror 16 and the interference light Ib between the measurement light reflected by the first surface and the reference light reflected by the reference mirror 16 is observed by the image sensor 21, and the intensity of the interference light Ib is determined. The maximum position P2 of the reference mirror 16 is measured by the length measuring machine 17 (step S25 in FIG. 6), and the interference light measurement process is terminated.

  After completing the interference light measurement process in step S2, the estimation unit 33 divides the optical path length difference l, which is the difference between the position P1 and the position P2, by the refractive index n with respect to the light source wavelength of the glass type forming the desired lens L. Thus, the lens center thickness d is estimated (step S3).

  The determination unit 34 determines whether or not the lens center thickness d of the test lens L1 estimated by the estimation unit 33 is within a range set based on the lens center thickness d1 calculated by the measurement unit 32 (step S4).

  When the determination unit 34 determines that the estimated lens center thickness d of the test lens L1 is within the set range from the measured lens center thickness d1 (step S4, Yes), the control unit 36 determines that It is determined whether or not the quality determination for the lens is completed (step S5).

  When the quality determination is completed for all the test lenses (step S5, Yes), the quality determination process in the lens quality determination system 100 is ended.

  When the determination unit 34 determines that the estimated lens center thickness d of the test lens L1 is outside the predetermined range from the measured lens center thickness d1 (No in step S4), the display unit 35 causes the test lens L1 to be detected. Notifies that the lens is formed of a glass material different from the desired glass material (step S6). After the notification process, the process returns to step S5 to determine whether or not the quality determination has been completed for all the test lenses.

  In the lens quality determination process described above, the center thickness measurement process of the test lens L1 is performed first (step S1), and then the interference light measurement process of the test lens L1 is performed by the low coherence interference method (step S1). S2) The center thickness measurement process may be performed after the interference light measurement process of the lens L1. In addition, when there are many test lenses for judging quality, the interference light measurement process may be performed after measuring the center thickness of all the test lenses.

  In the first embodiment, the lens center thickness d of the test lens L1 is estimated using low coherence interferometry, and compared with the actually measured lens center thickness d1 of the test lens L1, the test lens L1 is desired. It is determined whether or not the lens is formed of a glass material. Since this determination can be performed without polishing the lens L1, it is possible to reduce the time and labor required for determining the quality of the lens L1. In addition, since the lens center thickness is measured using a non-contact type length meter, the appearance quality of the lens is not deteriorated.

(Modification 1 of Embodiment 1)
As a first modification of the first embodiment, a lens quality determination system using a lens center thickness measuring device having a distance adjusting mechanism that adjusts the distance between the sensor heads of two non-contact type length meters can be exemplified. it can. FIG. 7 is a schematic diagram illustrating a configuration of a lens center thickness measuring instrument 50B used in the lens quality determination system according to the first modification of the first embodiment.

  The lens center thickness measuring instrument 50B is the same as the lens center thickness measuring instrument 50 except that the lens center thickness measuring instrument 50B includes a length measuring instrument support 55B instead of the length measuring instrument support 55 of the lens center thickness measuring instrument 50 shown in FIG. It has the composition of.

  The length meter support portion 55B adjusts the distance D between the sensor heads 53a and 53b and the upper support portion 56b, the lower support portion 57b, the connecting portion 59 that connects the upper support portion 56b and the lower support portion 57b, and the sensor heads 53a and 53b. The adjusting screw 58 is provided. The upper support portion 56b is bent in a crank shape having a first overhang portion 56d overhanging the lens holding portion 60 and a second overhang portion 56c overhanging below the first overhang portion 56d. The second overhanging portion 56c is provided with a screw hole (not shown) into which the adjustment screw 58 is screwed. On the other hand, the lower support portion 57b is folded in a crank shape having a first overhang portion 57d projecting below the lens holding portion 60 and a second overhang portion 57c projecting outward above the first overhang portion 57d. The second overhanging portion 57c is provided with a through hole (not shown) through which the adjustment screw 58 is inserted. However, the penetration length of the adjustment screw 58 in the above-described through hole is kept constant by a stopper (not shown) provided on the adjustment screw 58.

  Further, the upper support portion 56b and the connecting portion 59 are connected so that the upper support portion 56b can slide up and down along the connecting portion 59 and the upper support portion 56b having the connecting portion 59 as an axis cannot rotate. The lower support part 57b and the connecting part 59 are fixed to each other. Therefore, when the adjustment screw 58 is rotated in the screwing direction into the screw hole, the upper support portion 56b slides downward along the connecting portion 59, and when the adjustment screw 58 is rotated in the direction opposite to the screwing direction, the upper support portion. 56b slides upward along the connecting portion 59. In FIG. 7, the moving direction of the upper support part 56b is indicated by a solid arrow A.

  The length measuring body 52a of the non-contact type length measuring device 51a is attached to the first overhanging portion 56d of the upper support portion 56b, and the length measuring body of the non-contact type length measuring device 51b is attached to the first overhanging portion 57d of the lower side supporting portion 57b. Since the lens center thickness measuring instrument 50B is attached to the lens center thickness measuring instrument 50B, the measuring instrument manually adjusts the rotation direction and the rotation amount of the adjusting screw 58, so that the length measuring instrument main body 52a is moved along the measurement axes MA1 and MA2. The distance D between the sensor heads 53a and 53b can be adjusted by moving the sensor head. The upper support portion 56b, the second overhang portion 57c of the lower support portion 57b, the connecting portion 59, and the adjustment screw 58 constitute the distance adjustment mechanism DR described above.

  When the lens center thickness is measured using the lens center thickness measuring instrument 50B described above, the distance D between the sensor heads 53a and 53b can be adjusted by the distance adjustment mechanism DR. It is possible to measure the lens center thickness of the analyzing lens, and there is an effect that the convenience is high. Further, the lens quality determination system according to the first modification including the lens center thickness measuring device 50B polishes the lens L1 to determine whether or not the test lens L1 is a lens formed of a desired glass material. Therefore, the quality determination of the lens L1 can be performed without taking time and effort.

(Modification 2 of Embodiment 1)
As a second modification of the first embodiment, a lens quality determination system using a lens center thickness measuring instrument having a centering portion that centers the test lens by sandwiching and fixing the test lens from both sides in the thickness direction is illustrated. be able to. FIG. 8 is a schematic diagram illustrating a configuration of a lens center thickness measuring instrument 50C used in the lens quality determination system according to the second modification of the first embodiment.

  The lens center thickness measuring instrument 50C is shown in FIG. 7 except that a lens holding part 60C is provided instead of the lens holding part 60 shown in FIG. 7 and a centering part 65 is provided. It has the same configuration as the lens center thickness measuring instrument 50B.

  In addition to the lens support member 61, the lens holding unit 60C has a position adjustment mechanism PR that displaces the position of the test lens L1 held by the lens support member 61 along the measurement axes MA1 and MA2. is doing. This position adjusting mechanism PR adjusts the position of the test lens L1 according to the shape, size, thickness, etc. of the test lens L1, or according to the width of the measurable range of each non-contact type length meter 51a, 51b. It is displaceable along the measurement axes MA1 and MA2, and includes two guide shafts 63a and 63b and two connecting portions 62a and 62b. The guide shafts 63a and 63b support the lens support member 61 and guide the displacement direction when the lens support member 61 is displaced along the measurement axes MA1 and MA2. Further, the connecting portions 62a and 62b connect the lens support member 61 to the guide shafts 63a and 63b so as to be slidable and position-fixable.

  For example, if the lens support member 61 is displaced downward and the lens L1 is arranged, then the lens support member 61 is displaced upward to a desired height along the measurement axes MA1 and MA2, even if each lens Even when the measurable range of the contact-type length meters 51a and 51b is relatively narrow and the distance D between the sensor heads 53a and 53b is relatively short, the lens support member 61 is fixed around the center of the distance D. Thus, the test lens L1 can be easily disposed on the lens support member 61.

  The centering portion 65 has a pair of yatoys that enable the test lens L1 to be centered by sandwiching and fixing the test lens L1 from both sides in the thickness direction, that is, an upper yato 66a and a lower yato 66b. is doing. Each of the pair of Yatoi 66a and 66b has a ring shape, and the thickness, inner diameter, outer diameter, etc. of the pair of yatois 66a, 66b are in contact with the test lens L1 outside the effective diameter of the test lens L1. It is appropriately selected according to the shape and size of the lens L1.

  Further, the centering portion 65 includes, in addition to the pair of Yatoi 66a, 66b, a Yatei shaft 67a, a cylindrical Yatoi holder 68a provided coaxially with the Yatoi shaft 67a on the outer periphery of the Yatoi shaft 67a, and a Yatei shaft 67b. And a cylindrical Yatoi holder 68b provided coaxially with the Yatoi shaft 67b on the outer periphery of the Yatoi shaft 67b, and a Yatoi shaft support portion 69 for holding the respective Yatoi shafts 67a and 67b coaxially with the measurement axes MA1 and MA2. ing. The yatoi holder 68a is slidable along the yatoi shaft 67a and can be fixed in position. The upper yato 66a is attached to the lower end of the yatoi holder 68a coaxially with the yatoi holder 68a. Similarly, the yatoi holder 68b is slidable along the yatoi shaft 67b and can be fixed in position, and the lower yatoi 66b is attached to the upper end of the yatoi holder 68b coaxially with the yatoi holder 68b.

  By sliding the Yatoi holder 68a along the Yatoi shaft 67a, the upper Yatoi 66a can be brought into contact with the lens surface La of the subject lens L1 from above the subject lens L1. Similarly, by sliding the Yatoi holder 68b along the Yatoi shaft 67b, the lower Yatoi 66b can be brought into contact with the lens surface Lb of the test lens L1 from below the test lens L1. The yato shaft support portion 69 includes an upper yato shaft holding portion 69a disposed above the length measuring device support portion 55D, a lower yato shaft holding portion 69b disposed below the length measuring device support portion 55D, and It has a connecting portion 69c for connecting the Yatoi shaft holding portions 69a and 69b to each other, and is fixed to the lower support portion 57b of the length measuring meter support portion 55D by a jig not shown.

  The measurement of the lens center thickness d1 of the lens L1 to be measured by the lens center thickness measuring device 50C described above can be performed in the same manner as the lens center thickness measurement process described in the first embodiment, but a master whose lens center thickness is known. The center thickness of the test lens may be obtained using a lens. FIG. 9 is a flowchart showing another example of the center thickness measuring process of the lens to be tested when the lens center thickness measuring device of FIG. 8 is used.

  First, a master lens with a known lens center thickness is placed on the lens holding portion 60C (step S31). The master lens is disposed on the lens support member 60C with its optical center and its periphery exposed. At this time, if necessary, the height of the lens support member 61 is adjusted in advance to a desired height by the position adjustment mechanism PR.

  Thereafter, if necessary, the measurer manually operates the position adjustment mechanism PR to displace the lens support member 61, whereby the position of the master lens disposed in the lens holding portion 60C is measured along the measurement axes M1 and M2. To a desired position (step S32).

  The measurer manually adjusts the position of each of the pair of yatois 66a and 66b, and fixes the master lens disposed on the lens support member 61 by sandwiching the pair of yatois 66a and 66b from both sides in the thickness direction. Thus, the optical axis of the master lens is aligned with the measurement axes MA1 and MA2 (step S33).

  For example, after the lower yato 66b is brought into contact with the lower lens surface (non-contact type length measuring instrument 51b side) of the master lens, the upper yato 66a is moved upward (non-contact type length measuring instrument 51a side) of the master lens. The master lens is centered by being brought into contact with the lens surface and sandwiched between the yatois 66a and 66b so that the optical axes of the master lens coincide with the measurement axes MA1 and MA2. When the shape and size of the master lens are the same as the shape and size of the test lens L1, the inner ridge portion on the upper surface of the lower yato 66b contacts the lower lens surface over the entire circumference. The optical axis of the master lens coincides with the measurement axes MA1 and MA2 by adjusting the position of the master lens so that the outer edge of the lower surface of the upper yato 66a contacts the upper lens surface over the entire circumference. Can be made.

  Subsequently, the distance to the master lens is measured by each non-contact type length meter 51a, 51b (step S34). The non-contact type length meter 51a measures the distance from the sensor head to the upper lens surface La of the master lens, and the non-contact type length meter 51b is the lower lens surface Lb of the master lens from the sensor head. Measure the distance to.

  Thereafter, the master lens is removed from the lens holding unit 60C (step S35). Next, the test lens L1 is placed on the lens support member 61 of the lens holding portion 60C (step S36), and the test lens L1 is centered by being sandwiched and fixed by the yatois 66a and 66b from both sides in the thickness direction. The optical axis of the test lens L1 is made to coincide with the measurement axes MA1 and MA2 (step S37).

  Next, the distance to the lens L1 is measured by the sensor heads of the non-contact type length meters 51a and 51b (step S38), and the measuring unit 32 calculates the sum of the distances to the master lens measured in step S34, and the step The difference from the sum of the distances to the test lens L1 measured in S38 is obtained, and the lens center thickness of the test lens L1 is obtained from this difference and the lens center thickness of the master lens (step S39).

  Thereafter, the test lens L1 is removed from the lens holding unit 60C (step S40), and the test lens center thickness measurement process is terminated.

  When the lens center thickness is measured using the above-described lens center thickness measuring device 50C, the optical axis of the test lens L1 can be easily aligned with the measurement axes MA1 and MA2 by the centering unit 65. There is an effect that it is easy to accurately measure the lens center thickness of the lens L1. In addition, the lens quality determination system according to the second modification including the lens center thickness measuring device 50C polishes the lens L1 to determine whether or not the test lens L1 is a lens formed of a desired glass material. Therefore, the quality determination of the lens L1 can be performed without taking time and effort.

(Modification 3 of Embodiment 1)
As a third modification of the first embodiment, centering is performed by sandwiching and fixing the lens to be tested from the outside in the radial direction with a pair of yatoi arranged in a direction orthogonal to the measurement axis of the non-contact type length meter. A lens quality determination system using a lens center thickness measuring device 50D having a part can be exemplified. As the lens to be measured that is measured by the lens center thickness measuring instrument 50D according to the modified example 3, a lens that is molded so that the optical axis and the geometric center coincide with each other is used. FIG. 10 is a schematic diagram illustrating a configuration of a lens center thickness measuring instrument 50D used in the lens quality determination system according to the third modification of the first embodiment.

  The lens center thickness measuring instrument 50D has a lens support member 61D instead of the lens support member 61 shown in FIG. The lens support member 61D is a single flat plate member provided with a through hole Th having a predetermined shape and size (diameter), and each connecting portion 62a is arranged so that the measurement axes MA1 and MA2 pass through the through hole Th. , 62b are connected to the guide shafts 63a, 63b to constitute the position adjusting mechanism PR. The size of the through hole Th in the lens support member 61D is preferably equal to or greater than the effective diameter of the lens L1 that is molded so that the optical axis and the geometric center coincide with each other.

  The centering portion 65D has a movable Yato 70a and a fixed Yato 70b that can center the test lens L1 by sandwiching and fixing the test lens L1 from the outside in the radial direction. The movable Yatoi 70a and the fixed Yatoi 70b are arranged on the lens support member 61D with their central axes CA (horizontal axes) aligned. The movable Yatoi 70a is slidable and position-fixable in a direction orthogonal to the measurement axes MA1 and MA2 along a guide portion (not shown) provided on the lens support member 61D, and this direction is fixed to the center axis CA. Parallel to the extending direction. On the other hand, an adjustment hole (not shown) is formed in the fixing yatoi 70b, and a fixing tool (not shown) such as a screw that is fixed to the lens support member 61D through the adjustment hole is provided on the lens support member 61D. It is fixed to. However, the adjustment hole is a long hole that is long in the direction along the central axis CA. By appropriately changing the relative position of the fixing tool in the adjustment hole and fixing the fixing yato 70b to the lens support member 61D, The mounting position of the fixed yatoy 70b can be changed.

  Further, the movable Yatoi 70a and the fixed Yatoi 70b are provided with V-shaped notches, and these notches are brought into contact with the outer peripheral surface of the lens L1 to be examined. Depending on the size of the lens L1, the mounting position of the fixed lens 70b is appropriately changed, the moving lens 70a is appropriately displaced, and the lens L1 is sandwiched from the outside in the radial direction by the moving lens 70a and the fixed lens 70b. By fixing, the test lens L1 can be centered.

  When the lens center thickness is measured using the lens center thickness measuring instrument 50D described above, the optical axis of the test lens L1 can be easily aligned with the measurement axes MA1 and MA2 by the centering portion 65D. There is an effect that it is easy to accurately measure the lens center thickness of the lens L1. In addition, the lens quality determination system according to the third modification including the lens center thickness measuring device 50D polishes the lens L1 to determine whether or not the test lens L1 is a lens formed of a desired glass material. Therefore, the quality determination of the lens L1 can be performed without taking time and effort.

(Modification 4 of Embodiment 1)
As a fourth modification of the first embodiment, a lens quality determination method using a single-side contact type lens center thickness measuring device 50E that measures a lens center thickness by bringing a measurement terminal into contact with only one lens surface of a lens to be tested. Can be illustrated. The lens center thickness measuring device 50E according to the modified example 4 is used for measuring the lens center thickness of a test lens in which one lens surface is formed into a flat surface, such as a single convex lens or a single concave lens. FIG. 11 is a schematic diagram illustrating a configuration of a lens center thickness measuring instrument 50E used in the lens quality determination method according to the fourth modification of the first embodiment.

  The lens center thickness measuring instrument 50 </ b> E includes a dial gauge 81 and a support stand 86 that supports the dial gauge 81.

  The dial gale 81 has a spindle 83 having a measurement terminal 82 that abuts the lens surface of the lens L1 to be tested on the tip side, a display unit 84 that displays a measurement value by a pointer, and a cylindrical shape that slidably holds the spindle 83. The stem 85 is provided. The support stand 86 includes a base 86B having a measurement base 86A, a support 86C erected on the base 86B, and a support 86C attached to the support 86C, and a measurement base 86A on which the lens L1 is placed. And a bracket 86D that is held above. The test lens L1 is set on the measurement table 86A with the lens surface molded into a flat surface facing downward, and the lens center thickness d1 of the test lens L1 is measured by the dial gauge 81.

  In order to measure the lens center thickness with the lens center thickness measuring instrument 50E, the vertical position of the spindle 83 of the dial gauge 81 is adjusted to bring the measurement terminal into contact with the upper surface of the measuring table 86A. Reset the value to 0 (zero). Thereafter, the spindle 83 of the dial gauge 81 is moved upward, the lens L1 to be tested is set on the measurement table 86A so that the center (optical axis) of the lens is below the measurement terminal 82, and then the spindle 83 is lowered. The measurement terminal 82 is brought into contact with the center of the lens. The measured value of the dial gauge 81 at this time is the lens center thickness.

  In the fourth modification, the center thickness of the test lens L1 is measured by the lens center thickness measuring device 50E, the center thickness of the test lens L1 is estimated by the low coherence interferometer 10, and the measured lens center thickness is estimated. By comparing the obtained lens center thicknesses, it is possible to easily determine whether or not the test lens L1 is a lens formed of a desired glass material.

(Modification 5 of Embodiment 1)
As a fifth modification of the first embodiment, a lens quality determination method using a double-contact type lens center thickness measuring device 50F that measures a lens center thickness by bringing a measurement terminal into contact with both lens surfaces of a test lens. It can be illustrated. The lens center thickness measuring device 50F according to the modified example 5 is used for measuring the lens center thickness of a lens to be tested in which both lens surfaces are formed into curved surfaces, such as a biconvex lens, a biconcave lens, and a meniscus lens. FIG. 12 is a schematic diagram illustrating a configuration of a lens center thickness measuring instrument 50F used in the lens quality determination method according to the fifth modification of the first embodiment.

  The lens center thickness measuring instrument 50F includes a dial gauge 81F, a micrometer head 87 as a reference length measuring base, and a stand (not shown) that individually holds the dial gauge 81F and the micrometer head 87 via a bracket (not shown). Not).

  The dial gauge 81F includes a spindle 83A including a measurement terminal and a display unit 84. The micrometer head 87 includes a spindle 83B and a simple 88 that advances and retracts the spindle 83B by its rotation.

  In order to measure the lens center thickness d1 with the lens center thickness measuring instrument 50F, the vertical position of the spindle 83A of the dial gauge 81F is adjusted, and the measurement terminal of the spindle 83A is brought into contact with the upper end surface of the spindle 83B of the macrometer head 87. At this time, the measured value of the dial gauge for inspection is reset to 0 (zero). Thereafter, the spindle 83A of the dial gauge 81F is moved upward so that the lens center (optical axis) of the lens L1 is positioned below the measurement terminal of the dial gauge 81F and above the spindle 83B of the micrometer head 87. After setting, the spindle 83A of the dial gauge 81F is lowered to bring the measurement terminal into contact with the center of the lens. The measured value of the dial gauge at this time is the lens center thickness d1.

  In the fourth modification, the center thickness of the test lens L1 is measured by the lens center thickness measuring instrument 50F, and the center thickness of the test lens L1 is estimated by the low coherence interferometer 10, and the measured lens center thickness is estimated. By comparing the obtained lens center thicknesses, it is possible to easily determine whether or not the test lens L1 is a lens formed of a desired glass material.

(Embodiment 2)
The lens quality determination system according to the second exemplary embodiment uses the lens center thickness of the test lens measured by the lens center thickness measuring instrument instead of the estimation unit that estimates the center thickness of the test lens by low coherence interferometry. The lens quality determination system 100 according to the first embodiment is different from the lens quality determination system 100 according to the first embodiment in that it includes a refractive index calculation unit that calculates the refractive index of the subject lens.

  FIG. 13 is a schematic diagram illustrating a configuration of a lens quality determination system 200 according to the second embodiment. The lens quality determination system 200 includes a measurement processing unit 30A having a refractive index calculation unit 37 that calculates the refractive index of the lens L1.

  Next, the quality determination process of the lens L1 to be tested in the lens quality determination system 200 according to the second embodiment will be described with reference to FIG. FIG. 14 is a flowchart of a lens quality determination process according to the second embodiment.

  In the lens quality determination system 200 according to the second embodiment, the center thickness measurement process of the lens L1 to be measured is performed by the lens center thickness measuring instrument 50 in the same manner as in step S1 and step S2 of the lens quality determination process according to the first embodiment. (Step S41), and the interference light Ia between the measurement light and the reference light reflected from the first surface of the lens L1 and the interference light between the measurement light and the reference light reflected from the second surface by the low coherence interference method. Interfering light measurement processing for measuring the position (P1 and P2) of the reference mirror 16 where the intensity of Ib is maximized by the length measuring machine 17 is performed (step S42).

  Thereafter, the refractive index calculation unit 37 calculates the optical path length difference l based on the measured positions P1 and P2 of the reference mirror 16, and uses the lens center thickness d1 measured by the lens center thickness measuring instrument 50 to measure the subject lens L1. The refractive index n1 is calculated (step S43).

  The determination unit 34 determines whether or not the refractive index n1 of the lens L1 calculated by the refractive index calculation unit 37 is within a predetermined range with respect to the desired refractive index n of the lens glass material (step S44).

  When the determination unit 34 determines that the calculated refractive index n1 of the lens L1 is within a predetermined range with respect to the desired refractive index n of the lens glass material (step S44, Yes), the control unit 36 It is determined whether or not the quality determination has been completed for the test lens L1 (step S45). When the quality determination has been completed for all the test lenses L1 (step S45, Yes), the lens quality determination system 200 The quality determination process ends.

  When the determination unit 34 determines that the calculated refractive index n1 of the test lens L1 is outside the predetermined range with respect to the desired refractive index n of the lens glass material (step S44, No), the display unit 35 displays the test lens 35. L1 is notified that the lens is formed of a glass material different from the desired glass material (step S46), and the determination in step S45 is performed again.

  In the second embodiment, the refractive index of the test lens L1 is calculated using the optical path length difference l of the test lens L1 obtained by the low coherence interferometry and the lens center thickness d1 measured by the lens center thickness measuring device 50. By calculating n1, and comparing the calculated refractive index n1 with the refractive index n of the desired lens glass material, it is easily determined whether or not the lens L1 is a lens formed of the desired glass material. be able to.

  The lens quality judgment method and the lens quality judgment system of the present invention can be used for discrimination of lens glass types in a lens manufacturing process.

DESCRIPTION OF SYMBOLS 10 Low coherence interferometer 11 Low coherence light source 12, 19 Collimator lens 13, 20 Polarizing plate 14 Polarizing beam splitter 15, 18 λ / 4 plate 16 Reference mirror 17 Measuring machine 21 Image sensor 30, 30A Measurement processing unit 31 Image processing unit 32 Measurement unit 33 Estimation unit 34 Judgment unit 35 Display unit 36 Control unit 37 Refractive index calculation unit 50, 50B, 50C, 50D, 50E, 50F Lens center thickness measuring instrument 51a, 51b Non-contact type length meter 55 Length meter support unit 60 Lens holding part 65, 65D Centering part 53a, 53b Sensor head 58 Adjustment screw 61 Lens support member 66a Upper side door 66b Lower side door 70a Moving joint 70b Stationary joint 100, 200 Lens quality determination system L1 Test lens DR Distance adjustment mechanism PR Position adjuster Structure

Claims (10)

In a lens quality determination method for determining the quality of a lens using light emitted from a low-coherence light source,
An actual measurement step for measuring the center thickness of the lens;
The light from the low-coherence light source is divided into reference light and measurement light, and the measurement light is applied to the first surface or the second surface of the lens, and the reference light is applied to the reference mirror and reflected by the first surface. A measurement step for measuring the position of the reference mirror at which the intensity of the interference light between the measurement light and the reference light and the interference light between the measurement light reflected by the second surface and the reference light is maximum;
An optical path length difference is calculated based on the position of the reference mirror measured in the measurement step, and an estimation step of estimating the center thickness of the lens using a refractive index of a glass material that is a material of the lens;
A determination step for determining whether the center thickness of the lens estimated in the estimation step is within a range set based on the center thickness of the lens actually measured in the actual measurement step;
A lens quality determination method comprising:   2. The method of claim 1, further comprising: a notifying step for notifying that the type of glass material of the lens is different when the center thickness of the lens estimated in the estimating step is determined to be outside a setting range in the determining step. The lens quality determination method described in 1. In a lens quality determination method for determining the quality of a lens using light emitted from a low-coherence light source,
An actual measurement step for measuring the center thickness of the lens;
The light from the low-coherence light source is divided into reference light and measurement light, and the measurement light is applied to the first surface or the second surface of the lens, and the reference light is applied to the reference mirror and reflected by the first surface. A measurement step for measuring the position of the reference mirror at which the intensity of the interference light between the measurement light and the reference light and the interference light between the measurement light reflected by the second surface and the reference light is maximum;
A refractive index calculation step of calculating an optical path length difference based on the position of the reference mirror measured in the measurement step, and calculating a refractive index of the lens using a lens center thickness of the lens measured in the measurement step;
A determination step of determining whether or not the refractive index of the lens calculated in the refractive index calculation step is within a predetermined range;
A lens quality determination method comprising:   4. The method according to claim 3, further comprising a notifying step of notifying that the type of glass material of the lens is different when the refractive index of the lens calculated in the calculating step is determined to be outside a predetermined range in the determining step. The lens quality determination method described in 1. The actual measurement step includes
Two sensor heads of each of the two non-contact type length gauges, wherein at least the optical center of the lens is exposed between the two sensor heads arranged to face each other with their measurement axes aligned with each other. And an arrangement step of arranging the lens so that the optical axis of the lens to be tested coincides with the measurement axis;
A measurement step of measuring a distance from the two sensor heads to the lens by each of the two non-contact type length meters;
A step of calculating a lens center thickness of the lens by subtracting a sum of distances to the lens measured by each of the two non-contact type length meters from a distance between the two sensor heads;
The lens quality determination method according to any one of claims 1 to 4, further comprising:   6. The lens quality determination method according to claim 5, wherein the actual measurement step includes a second measurement step of measuring a distance between the two sensor heads before the calculation step. The actual measurement step includes
Two sensor heads of each of the two non-contact type length gauges, each of which is a master lens having a known lens center thickness between two sensor heads that are arranged to face each other with their measurement axes aligned with each other. A master lens arrangement step of exposing the optical center at least and arranging the master lens so that the optical axis of the master lens coincides with the measurement axis;
A master lens measurement step of measuring a distance from the two sensor heads to the master lens by each of the two non-contact type length meters;
A lens disposing step of exposing at least an optical center of the lens between the two sensor heads, and disposing the lens so that an optical axis of the lens coincides with the measurement axis;
A lens measuring step of measuring a distance from the sensor head to the lens by each of the two non-contact type length meters;
The difference between the sum of the distances to the master lens measured in the master lens measurement step and the sum of the distances to the lenses measured in the lens measurement step is obtained, and from the difference and the lens center thickness of the master lens The lens quality determination method according to claim 1, further comprising: calculating a lens center thickness of the lens. In a lens quality determination system that determines the quality of a lens using light emitted from a low-coherence light source,
A lens center thickness measuring instrument for measuring the center thickness of the lens;
The light from the low-coherence light source is divided into reference light and measurement light, and the measurement light is applied to the first surface or the second surface of the lens, and the reference light is applied to the reference mirror and reflected by the first surface. Measuring means for measuring the position of the reference mirror where the intensity of the interference light between the measured light and the reference light and the interference light between the measurement light reflected on the second surface and the reference light is maximized,
An optical path length difference is calculated based on the position of the reference mirror measured by the measurement unit, and an estimation unit that estimates the center thickness of the lens using a refractive index of a glass material that is a material of the lens;
Determining means for determining whether the center thickness of the lens estimated by the estimating means is within a range set based on the center thickness of the lens measured by the lens center thickness measuring device;
If the determination means determines that the center thickness of the lens estimated by the estimation means is outside the set range, a notification means for notifying that the type of glass material of the lens to be tested is different;
A lens quality judgment system comprising: In a lens quality determination system that determines the quality of a lens using light emitted from a low-coherence light source,
A lens center thickness measuring instrument for measuring the center thickness of the lens;
The light from the low-coherence light source is divided into reference light and measurement light, and the measurement light is applied to the first surface or the second surface of the lens, and the reference light is applied to the reference mirror and reflected by the first surface. Measuring means for measuring the position of the reference mirror where the intensity of the interference light between the measured light and the reference light and the interference light between the measurement light reflected on the second surface and the reference light is maximized,
Refractive index calculating means for calculating the optical path length difference based on the position of the reference mirror measured by the measuring means, and calculating the refractive index of the lens using the lens center thickness measured by the lens center thickness measuring device;
Determining means for determining whether or not the refractive index of the lens calculated by the refractive index calculating means is within a predetermined range;
If the determination means determines that the refractive index of the lens calculated by the refractive index calculation means is outside a predetermined range, a notification means for notifying that the type of glass material of the lens to be tested is different;
A lens quality judgment system comprising: The lens center thickness measuring instrument is
Two non-contact type length gauges having a sensor head for distance measurement;
A length-measuring support unit that supports the sensor heads of the two non-contact type length-measuring devices facing each other, and supports the measurement axes of the sensor heads so as to coincide with each other;
A lens holding portion that is provided between the sensor heads, exposes at least the optical center of the test lens, and holds the test lens such that the optical axis of the test lens coincides with the measurement axis;
The lens quality determination system according to claim 8 or 9, further comprising:

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