JP2002039724A - Internal hole surface inspecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal hole surface inspecting device which can prevent measurement precision depending upon the focal length of an objective from decreasing and measure the internal diameter, uneven state, etc., of a hole part of a measured body with high precision. SOLUTION: The light beam emitted by a light source (32) is converged through a condenser lens (31) and further passed through a relay lens (23) to obtain nearly parallel luminous flux, which is guided in an optical lens barrel (20) to irradiate the internal hole surface of the measured body through a reflector (21) and an objective (22); and its reflected light is converged and guided in the optical lens barrel. Then the focusing state is detected from reflected light obtained through a beam splitter (34) to displace the condenser lens or relay lens along its optical axis (focus adjusting mechanism 33) and the distance between the objective and the internal hole surface of the measured body from the quantity of displacement of the condenser lens or relay lens when the focusing is detected (distance measuring means 39).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hole inner surface inspection apparatus capable of measuring the inner diameter of a hole in an object to be measured in a non-contact manner with a high accuracy using a light beam. About.

[0002]

2. Description of the Related Art Conventionally, a micrometer is generally used for measuring the inner diameter of a cylindrical hole (hole) in a cylinder block or the like, but there is a fear that the inner surface of the cylindrical hole may be damaged by the contact. Non-contact type micrometers (measuring devices) such as air-type and capacitance-type have also been developed. However, it is necessary to form the measuring head with the same size as the inside diameter of the cylindrical hole of the object to be measured. In addition, there is a problem that the management of the gap (gap) between the measuring head and the inner surface of the cylindrical hole of the measured object is troublesome.

[0003]

Therefore, recently, the focusing position is changed using the longitudinal magnification of an optical system (lens) for irradiating the object to be measured with light, and the optical axis of the lens is changed according to the information of the focal point. A method (confocal method) of measuring the inner diameter of a cylindrical hole by calculating the distance between the lens and the object to be measured from the displacement in the direction has been proposed. This type of apparatus generally condenses a light beam emitted from a light source 1 through an objective lens (condensing lens) 2 and guides it into an optical lens barrel 3 as shown in FIG. After irradiating the inner surface 5 of the cylinder to be measured through the reflecting mirror 4 provided at the tip of the cylinder 3 and condensing the reflected light coaxially with the light beam through the objective lens 2, the reflected light is It is configured to guide the light to the light receiver 7 via the beam splitter 6. Then, the focus detecting unit 8 detects a shift in the focal position of the light beam irradiated on the inner surface 5 of the cylinder from a change in a light receiving pattern of the light reflected by the light receiver 7 and drives the lens driving mechanism 9 to drive the objective lens. 2 is displaced in the direction of the optical axis to adjust the focus position (focus adjustment) of the light beam with respect to the inner surface 5 of the cylinder. Then, the distance between the objective lens 2 and the inner surface 5 of the cylinder and the distance between the optical center where the reflecting mirror 3 is provided and the inner surface 5 of the cylinder are determined from the displacement amount of the objective lens 2.

However, in the measuring apparatus constructed as described above, the focal length of the objective lens 2 is set in consideration of the optical path length up to the inner surface 5 of the cylinder, which is set by bending the optical axis via the reflecting mirror 3. Is necessary, and it cannot be denied that the focal length becomes long. For this reason, there is a problem that the measurement resolution (measurement accuracy) cannot be sufficiently increased.

The present invention has been made in view of such circumstances, and an object of the present invention is to prevent a decrease in measurement accuracy depending on the focal length of an objective lens, and to prevent an inner diameter of a cylindrical hole or a hole in the object to be measured. It is an object of the present invention to provide a hole inner surface inspection apparatus having a simple configuration capable of measuring the state of unevenness on the inner surface with a high accuracy using a light beam.

[0006]

In order to achieve the above-mentioned object, a hole inner surface inspection apparatus according to the present invention comprises an optical lens barrel inserted into a hole of an object to be measured. A light beam is applied to the inner surface of the hole of the device under test to optically inspect the inner diameter of the hole and the state of irregularities from the reflected light, and the light beam is emitted from the light source as described in claim 1. An optical system for introducing the light introduced into the optical column, a relay lens for guiding the light introduced into the optical column as a light beam forming a substantially parallel light beam, and a tip of the optical column. A reflecting mirror that bends the optical axis of the light beam in a direction perpendicular to the light beam, and irradiates the light beam bent or bent by the reflecting mirror onto the inner surface of the hole of the object to be measured and reflects the light beam. Condensing light coaxially with the light beam to form the light An objective lens to be introduced into the lens barrel in a reverse direction, and a focus adjustment mechanism for displacing the relay lens in the optical axis direction to change a focus position of light emitted from the objective lens to an inner surface of the hole of the device under test. And The reflected light guided in the opposite direction through the optical lens barrel is separated from the light emitted from the light source by a beam splitter provided in the optical system, and the separated reflected light is received by a light receiver. Detecting the in-focus state of the light beam emitted from the objective lens to the inner surface of the hole of the object to be measured, and calculating the in-focus state from the displacement amount of the relay lens when the in-focus state is detected from the reflected light. It is characterized in that the distance between the objective lens and the inner surface of the hole of the object to be measured is measured (distance measuring means).

According to another aspect of the present invention, a hole inner surface inspection apparatus according to the present invention includes a condenser lens for condensing a light beam output from a light source and introducing the light beam into the optical barrel.
A relay lens that guides the light introduced into the optical barrel by the condenser lens as a light beam that forms a substantially parallel light beam, and a relay lens that is provided at the tip of the optical barrel and passes through the optical barrel. A reflecting mirror that bends the optical axis of the guided light beam at a right angle, and the optical axis is bent through the reflecting mirror, or the bent light beam is converged and irradiated onto the inner surface of the hole of the object to be measured. An objective lens that condenses the reflected light coaxially with the light beam and introduces the reflected light into the optical barrel in the opposite direction; and displaces the condensing lens or the relay lens in the optical axis direction to remove the reflected light from the objective lens. A focus adjustment mechanism for changing a focus position of light applied to the inner surface of the hole of the measurement object. Then, the reflected light guided in the opposite direction through the optical lens barrel is separated from the light output from the light source using a beam splitter provided between the light source and the condenser lens, The reflected light separated by the splitter is received by a light receiver, and a focused state of the light beam emitted from the objective lens on the inner surface of the hole of the measured object is detected. And measuring the distance between the objective lens and the inner surface of the hole of the object to be measured from the amount of displacement of the focusing lens or the relay lens when the in-focus state is detected from the reflected light (distance measuring means). Features.

That is, according to the present invention, the light introduced from the light source into the optical lens barrel is guided through the relay lens as a light beam forming a substantially parallel light beam through the optical lens barrel, and is fixed to the tip of the optical lens barrel. The focal length of the objective lens is set to be sufficiently short by converging the light beam via the provided objective lens and irradiating the light beam on the inner surface of the hole of the object to be measured. The condensing lens for introducing light into the optical barrel, or the relay lens for guiding the light introduced into the optical barrel as a light beam forming a substantially parallel light beam through the optical lens. By displacing in the axial direction, focus adjustment (focus adjustment) of the light beam irradiated on the object to be measured via the objective lens is performed, thereby increasing the distance between the objective lens and the inner surface of the hole of the object to be measured. The feature is that the measurement is performed with high accuracy.

In a preferred aspect of the present invention, the reflecting mirror is rotatably provided around an optical axis of a light beam formed by the relay lens as a rotation axis.
The focus adjusting mechanism may be configured to displace the relay lens or the condenser lens according to a focus state of the reflected light detected by the light receiver.

According to another preferred aspect of the present invention, the focus adjustment mechanism is configured to repeatedly displace the relay lens or the condenser lens with a predetermined displacement width. In the distance measuring means, the amount of displacement of the relay lens or the condenser lens when the focused state is detected from the reflected light, as the distance between the objective lens and the inner surface of the hole of the object to be measured It is configured to capture.

In a preferred aspect of the present invention, the condenser lens is provided by forming a collimator optical system between the light source and the light source, and the beam splitter is incorporated in the collimator optical system. It is characterized by: Further, the hole inner surface inspection apparatus according to the present invention includes an optical system that introduces light emitted from a light source into the optical barrel as described in claim 9, and a substantially parallel light beam that introduces light introduced into the optical barrel. A relay lens that guides the inside of the optical barrel as a light beam, and a reflecting mirror that is provided at the tip of the optical barrel and that bends the optical axis of the light beam in a right angle direction. An objective lens that converges the bent light beam and irradiates the inside of the hole of the object to be measured with light, condenses the reflected light coaxially with the light beam, and introduces the reflected light into the optical barrel in the opposite direction; A beam splitter that is provided between a light source of an optical system and the relay lens and separates reflected light guided in the opposite direction through the optical lens barrel from light emitted from the light source, and separated by the beam splitter Was done And a light receiver for receiving the serial reflected light. Then, the light receiving pattern of the reflected light obtained by the light receiving device is analyzed to detect a deviation amount from a focused state of the light beam applied to the inner surface of the hole of the object to be measured. It is characterized in that it comprises a distance measuring means for determining the distance between the objective lens and the inner surface of the hole of the object to be measured.

[0012] In this case, preferably, the light receiver may be configured to convert the reflected light into a cylindrical light.
It is realized as having four divided light receiving areas for receiving light via a lens. The distance measuring means detects a change in the light receiving pattern of the reflected light from the light receiving amount in each light receiving area of the light receiving device, and detects a change amount ε of the light receiving pattern and a shift amount x from the focus position of the light beam. With reference to a table preliminarily storing the relationship between the objective lens and the object to be measured, the shift amount x from the in-focus position of the light beam is obtained, and this shift amount is added to the focus distance f of the objective lens. The distance between the object and the inner surface of the hole is determined.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a hole inner surface inspection apparatus according to an embodiment of the present invention. FIG. 1 is a view showing a schematic configuration of a hole inner surface inspection apparatus according to this embodiment, and 11 is a cylindrical hole (hole) 1 such as a cylinder block.
2 is an object to be measured. The hole inner surface inspection apparatus has an optical path of a light beam formed therein, and the above-described object to be measured 11
An optical lens barrel 20 which is inserted into the cylindrical hole 12 to irradiate the inner surface 13 of the cylindrical hole 12 with a light beam and collect the reflected light.
Is provided as the measuring head.

Thus, the optical lens barrel 20 is
A reflecting mirror 21 having a reflecting surface inclined at an angle of 45 ° with respect to the axial direction is provided at the tip of the reflecting mirror 21. The objective lens 22 is located at a position facing the reflecting mirror 21 in the horizontal direction. It has. The objective lens 22 is introduced from the upper end of the optical barrel 20 in the axial direction thereof, and
A light beam whose optical axis is bent at a right angle is converged via 1 and irradiates the inner surface 13 of the cylindrical hole 12, and the reflected light is condensed and the optical column is coaxial with the light beam. It plays the role of being introduced in the opposite direction into 20. The reflecting mirror 21 is formed of a plane mirror, a right-angle prism, or the like.
It is provided so as to be aligned with the center of the optical axis of the light beam guided inside 0.

At the upper end of the optical lens barrel 20, a relay lens 23 is provided. This relay lens 23
Constitutes an optical system for guiding the light beam (reflected light) as a substantially parallel light beam between the objective lens 22 (within the optical lens barrel 20). The length of the optical barrel 20 constituting such an optical system is fixedly set in advance according to the depth of the cylindrical hole 12 to be measured for the inner diameter. The optical barrel 20 is provided integrally with an optical unit 30 described later, and is supported by a barrel support mechanism 24 so as to be vertically movable. The lens barrel support mechanism 24 moves the optical lens barrel 20 up and down in accordance with the inner diameter measuring position (depth position) in the cylindrical hole 12, and adjusts the position of the lens barrel tip to the inner diameter measuring position. Carry.

The optical lens barrel 20 has, for example, a structure in which the tip end side on which the objective lens 22 is provided is rotatable about its axis as a rotation axis. It is provided as follows. Due to the rotation of the optical barrel 20, the direction of the objective lens 22 is changed to 360
Rotational scanning can be performed over °. Note that the center of the optical axis of the light beam guided inside the optical barrel 20 is
Basically, it is set so as to coincide with the axis center of the optical lens barrel 20.

On the other hand, an optical unit 30 provided integrally with the optical barrel 20 at a position above the optical barrel 20.
The condenser lens 31 faces the relay lens 23.
Is provided. The condensing lens 31 forms a collimator optical system between itself and a light source 32 provided in the optical unit 30. The condensing lens 31 condenses a light beam that forms a parallel light beam such as a laser beam emitted from the light source 32 to form the optical lens barrel. 20 and plays a role of guiding the reflected light introduced from the optical lens barrel 20 side to the light source 32 side as a parallel light flux as described later.
Incidentally, the condenser lens 31 is a lens having a relatively short focal length, is supported by an actuator 33 described later, and is provided movably in the optical axis direction.

The light beam condensed by the condensing lens 31 and introduced into the optical lens barrel 20 is converted into a substantially parallel light beam through the above-described relay lens 23 and travels inside the optical lens barrel 20. The inner surface 1 of the cylindrical hole 12 is guided and converged from the reflecting mirror 21 via the objective lens 22.
3 is irradiated. The reflected light of the light beam from the hole inner surface 13 is condensed through the objective lens 22 coaxially with the light beam and introduced into the optical lens barrel 20 in the opposite direction, and traces the optical path of the light beam in the opposite direction. Through the relay lens 23 to the condenser lens 31.

On the other hand, a beam splitter 34 is provided in the collimator optical system formed between the light source 32 and the condenser lens 31. The beam splitter 34 transmits the light beam emitted from the light source 32 and
1 and, as described above, reflects a part of the reflected light guided in the opposite direction from the optical lens barrel 20 side via the condenser lens 31 and separates the reflected light from the optical path of the light beam so as to be directed in the lateral direction. Play a guiding role. When a polarizing beam splitter is used as the beam splitter 34, the beam splitter 34
A quarter-wave plate 35 may be provided on the lower surface side of the device to shift the irradiation light and the reflected light guided to the beam splitter 34 by a half wavelength.

Now, a light receiver 36 which is disposed in such a manner as to face the reflection direction of the reflected light by the beam splitter 34.
Collects and receives the light separated by the beam splitter 34 via a lens 36a. The focus detection unit 37 provided with the light receiver 36 determines the focus state of the light converged by the objective lens 22 and radiated to the hole inner surface 13 based on the amount of light reflected by the light receiver 36 and the light reception pattern thereof. It has a function to detect Incidentally, the focus detection unit 37 irradiates the inner surface 13 of the cylindrical hole 12 through the objective lens 22 by using a differential detection method such as a beam size method, a knife edge method, an astigmatism method, and a Foucault method. It is configured to detect a focused state (a shift of a focal position) of the light beam to be focused on the inner surface 13 of the hole.

A lens drive mechanism 38 for driving the actuator 33 to displace the condenser lens 31 in the direction of the optical axis operates according to the information on the in-focus state detected by the in-focus detection section 37, for example. When a shift from the in-focus state of the light converged by the objective lens 22 and applied to the inner surface of the hole 13 is detected, the condensing lens 31 cancels the shift and detects the in-focus state.
It has a role to displace.

When the facing distance between the objective lens 22 and the inner surface 13 of the hole changes, the reflection position of the light radiated from the objective lens 22 to the inner surface 13 of the hole changes as shown in FIGS. The divergence angle of the reflected light introduced in the opposite direction into the optical lens barrel 20 via the objective lens 22 changes. Then, the reflected light introduced into the optical unit 30 in the opposite direction via the condenser lens 31 is no longer a parallel light flux, so that the light receiving pattern of the reflected light detected by the light receiver 36 changes as described above. . The focus detection unit 37 described above
The shift of the objective lens 22 from the in-focus state is detected from the change in the light receiving pattern of the reflected light.

Therefore, even if the distance between the objective lens 22 and the inner surface 13 of the hole changes, the reflected light condensed through the objective lens 22 is converted into a parallel light beam by the beam splitter 34 via the condenser lens 31. The condenser lens 31 is displaced in the optical axis direction so as to be guided. By changing the substantial focus position of the objective lens 22 by the displacement of the condenser lens 31, the focus state of the light irradiated by the objective lens 22 on the inner surface 13 of the hole is detected.

The data processing device 39 connected to the focus detection section 37 uses the focusing lens 31 by the focus detection section 37.
When focusing on the inner surface 13 of the hole of the (objective lens 22) is detected, the objective lens 22 and the inner surface 13 of the hole are determined based on the displacement of the actuator 33 (condensing lens 31) driven by the lens driving mechanism 38. It is responsible for calculating the distance of

Thus, according to the hole inner surface inspection apparatus having the optical system as described above, the light beam condensed by the condenser lens 31 is guided to the objective lens 22 as a substantially parallel light beam through the optical lens barrel 20. Irradiation is performed on the inner surface 13 of the cylindrical hole 12 through the objective lens 22. Therefore, the focal position at which the light beam condensed by the condenser lens 31 converges and the convergence position (focal position) of the light beam converged by the objective lens 22 and irradiated onto the hole inner surface 13 have a predetermined optical similarity relationship. They can be equivalently equivalent. Therefore, the focus detection unit 3
The focusing lens 3 according to the focus state detected at 7
By adjusting the position of the condenser lens 31 in the optical axis direction and detecting the position of the condenser lens 31 at the time of focusing, the condenser lens 31
Since the focal length is known, the position where the light beam condensed by the condensing lens 31 converges, and consequently, the position where the light beam condensed by the objective lens 22 converges can be obtained. In particular, it is possible to change the focus position of the light irradiated from the objective lens 22 toward the hole inner surface 13 without displacing the objective lens 22, and to simply and accurately adjust the distance between the objective lens 22 and the hole inner surface 13. Can be calculated.

In other words, the distance between the objective lens 22 and the hole inner surface 13 (the distance between the axis center of the optical lens barrel 20 and the hole inner surface 13)
Can be obtained. Then, while the optical lens barrel 20 is being rotated around its axis center (optical axis) as a rotation axis, the distance from the hole inner surface 13 over the entire inner peripheral surface of the tube hole 12 is obtained. Measure the inner diameter of 12,
In addition, it becomes possible to inspect the unevenness state of the inner surface 13 of the hole. In addition, the reflecting mirror 21 and the objective lens 22 are
0, so that the optical barrel 2
There is no danger that the optical condition changes due to the rotation of 0,
Stable measurement (inspection) can be performed over the entire circumference of the optical lens barrel 20.

If the inspection is performed by rotating the optical column 20 while vertically displacing the irradiation point of the light beam from the optical column 20, the inner surface 13 of the hole is also scanned in the depth direction. As a result, it is possible to execute the inspection while scanning the entire inner surface 13 of the hole. If the measurement is performed while the optical lens barrel 20 is displaced up and down, it is possible to inspect the hole inner surface 13 in the axial direction.

Further, according to the above configuration, the optical lens barrel 2
At 0, the light beam condensed by the condenser lens 31 is guided as a substantially parallel light beam through an optical system formed between the relay lens 23 and the objective lens 22, so that the focal length of the objective lens 22 is sufficiently short. Since the objective lens 22 need only be fixedly provided, it is possible to sufficiently increase the measurement accuracy depending on the focal length of the condenser lens 31 having a focus adjusting function. Therefore, effects such as simple and effective measurement accuracy can be obtained.

The present invention can be implemented as follows. For example, in the above-described embodiment, the lens driving mechanism 38 is operated according to the focus state detected by the focus detection unit 37, and the actuator 33 is driven to displace the condenser lens 31. However, instead of such a follow-up control method, the focus position of the objective lens 22 by repeatedly displacing the condenser lens 31 with a predetermined displacement width under the control of the lens driving mechanism 38 is shown as a characteristic A in FIG. Continuously. Then, the displacement of the condenser lens 31 at the time (timing) B when the focus is detected by the focus detection unit 37 from the change in the reflected light is detected as the distance between the objective lens 22 and the inner surface 13 of the hole. Is also good. For focus detection in this case, not only the above-described differential detection method but also a pin-pole detection method can be employed.

In particular, when the condenser lens 31 is focused while continuously reciprocatingly displacing the condenser lens 31 in this manner,
According to the measurement method for obtaining the first displacement position, there is an advantage that the control is simpler than the case where the following control method is used. In this case, the inner surface 1 of the cylindrical hole 12
Needless to say, it is sufficient to set the displacement width of the condenser lens 31 (the change width of the converging position of the light beam by the objective lens 22) in anticipation of the variation width due to the unevenness 3.

The hole inner surface inspection apparatus according to the present invention comprises:
For example, it is possible to configure as shown in FIG. In the embodiment shown in FIG. 4, the objective lens 22 is
The light beam converged through the objective lens 22 is provided in front of the reflecting mirror 21 at the position 0.
It is configured to irradiate the inner surface 13 of the second hole. By adopting such a configuration, it is not necessary to incorporate the objective lens 22 into the side surface of the optical lens barrel 20. For example, the diameter of the cylindrical hole 12 is small, and accordingly, the thickness of the optical lens barrel 20 needs to be reduced. It is suitable for the case where there is.

Also, as shown in FIG.
1 may be fixedly provided, and instead, the relay lens 23 may be configured to be displaced in the optical axis direction using an actuator 33. In this case, the focus adjustment by the relay lens 23 is performed according to the shift of the focus position of the light beam irradiated on the inner surface 13 of the cylindrical hole 12 via the objective lens 22 with respect to the inner surface 13 of the hole. Will be.
That is, in this case, by displacing the relay lens 23 in the optical axis direction, adjustment is made so that the image forming position of the reflected light on the light receiver 36 does not change. Therefore, based on the optical similarity between the in-focus position of the relay lens 23 and the in-focus position of the objective lens 22, the objective lens 22 and the hole inner surface 1 at the time of focusing are determined based on the displacement amount of the relay lens 23.
Since it is possible to calculate the distance to the third embodiment, the same effect as in the above-described embodiment can be obtained.

When the focus is adjusted by displacing the relay lens 23 in the optical axis direction in this way, a collimator optical system is formed between the light source 32 and the relay lens 23, for example, as shown in FIG. Without the relay lens 23
May be directly detected by the focus detection unit 37. In this case, there is an advantage that the optical lens system can be easily constituted by two lenses, that is, the relay lens 23 and the objective lens 22. That is,
In this case, the distance (focus position) between the relay lens 23 and the light source 32 (light receiver 36) is adjusted according to the distance between the objective lens 22 and the inner surface 13 of the hole. Based on the relationship between the focal length and the focal length of the objective lens 22, the distance between the objective lens 22 and the hole inner surface 13 can be calculated from the amount of displacement of the relay lens 23 in the optical axis direction.

In each of the embodiments described above, one of the condenser lens 31 and the relay lens 23 is displaced in the direction of the optical axis so that the reflected light is focused on the light receiver 36, and the displacement of the lens at that time is changed. The distance between the objective lens 22 and the inner surface of the hole 13 was measured from the amount. However, it is also possible to measure the distance without displacing the lens in this way.

FIG. 6 is a schematic configuration diagram showing the embodiment.
Basically, it is realized by configuring an optical system similar to each of the above-described embodiments. However, the difference is that a lens driving mechanism 38 for driving the condenser lens 31 or the relay lens 23 in the optical axis direction and an actuator 33 are not provided. Then, instead of the lens driving mechanism 38 and the like, the in-focus point detection unit 37 is slightly modified to analyze the light receiving pattern of the reflected light detected by the light receiver 36, thereby obtaining the distance between the objective lens 22 and the inner surface 13 of the hole. Is calculated.

That is, in the hole inner surface inspection apparatus according to this embodiment, the focus detection section 37 uses the beam splitter 3
After condensing the reflected light separated from 4 through the light receiving lens 36a, a cylindrical lens (cylindrical lens) is further formed.
The light receiving device 36 is configured to be guided to the light receiving device 36 via 36b. The cylindrical lens 36b has, for example, different focal lengths in the x-axis direction and the y-axis direction orthogonal to the optical axis, and plays a role of causing astigmatism in a convergent light beam system. Further, in correspondence with such a cylindrical lens 36b, a four-division type having a light-receiving area divided into four in the x-axis direction and the y-axis direction is used as the light receiver 36.

Such a cylindrical lens 36b
According to the focus detection unit 37 configured using the four-divided light receiver 36 and the light receiving pattern of the reflected light in the focused state, for example, as schematically shown in FIGS. FIG. 7 (b)
As shown in FIG. 7 (a), when the in-focus position is shifted to the front side, the shape becomes a vertically long ellipse as shown in FIG. 7 (a). ), It becomes a horizontally long ellipse. Therefore, the four-divided photodetector 36
If the light receiving amounts U, D, R, and L in the three light receiving regions 36U, 36D, 36R, and 36L are respectively detected, for example, (U + D)-(R + L) = 0, and the in-focus state can be detected. Further, the shift state of the focus position to the front side is detected as (U + D)-(R + L) = ε1> 0, and the shift state of the focus position to the rear side is detected as (U + D) − (R + L) = ε2 <0. can do.

The difference ε1, ε2 between the light receiving pattern in the vertical direction and the horizontal direction of the light receiving pattern thus obtained is a characteristic characteristic of the optical system as a displacement X from the in-focus position.
, For example, as shown in FIG. In the hole inner surface inspection apparatus according to this embodiment, a table 40 storing in advance an S-order curve as shown in FIG. 8 which is a characteristic of a light receiving pattern unique to the optical system.
It has. Then, the light receiving amount differences ε1, ε2 of the light receiving pattern of the reflected light detected by the above-mentioned four-segment type light receiver 36.
By obtaining the displacement amount X corresponding to the light receiving amount difference ε1, ε2 by referring to the table 40, the deviation amount of the optical system (objective lens 22) from the focused state with respect to the inner surface 13 of the hole is calculated. It is what you want.

Thus, according to such a configuration, when all the lenses in the optical barrel 20 are fixed,
Since the distance between the objective lens 22 and the inner surface of the hole 13 can be measured, there is an effect that the measurement can be performed with high accuracy without a mechanical error accompanying the movement of the lens. Can be Further, since the distance between the objective lens 22 and the inner surface of the hole 13 is obtained by analyzing the change in the light receiving pattern, there is an advantage that the measurement can be performed without causing a time delay due to the displacement control of the lens.

The present invention is not limited to the above embodiment. For example, as described above, the length of the optical barrel 20 may be determined according to the depth of the cylindrical hole 12 in the DUT 11, and the thickness of the optical barrel 20 is also
What is necessary is just to correspond to the diameter of the said cylindrical hole 12. Further, the roundness, cylindricity, minute defects, and the like may be inspected from the information on the inner surface 13 of the cylindrical hole 12 measured as described above.

Further, in the above-described embodiment, the optical unit 30 is fixedly provided, and only a part of the optical lens barrel 20 is rotated about its axis as a rotation axis.
The entire optical barrel 20 or the optical unit 30 and the optical barrel 20 may be integrally rotated. What part of the optical system described above is configured as the optical lens barrel 20 may be determined according to its specifications. Specifically, the reflecting mirror 21 and the objective lens 2
2 may be incorporated into the optical lens barrel 20, and conversely, the relay lens 23 and the condenser lens 31 may be incorporated into the optical lens barrel 2.
0 can also be incorporated.

When the distance is measured with the lens fixed, any differential detection method such as the beam size method other than the astigmatism method, the knife edge method, and the Foucault method can be adopted. In addition, for example, by using a method called a critical angle prism method, parallel light flux is guided to a light receiver via a critical angle prism, so that the light reaching the light receiver diverges or converges depending on whether the light reaches the light receiver. It is also possible to detect the deviation from the in-focus state. In addition, the present invention can be variously modified and implemented without departing from the gist thereof.

[0043]

As described above, according to the present invention, the distance between the objective lens and the object can be measured without increasing the focal length of the objective lens for irradiating the object with the light beam. Therefore, the measurement accuracy can be simply and effectively increased. In addition, the focusing position can be adjusted by displacing the focusing lens that introduces light into the optical barrel or the relay lens that guides the light introduced into the optical barrel into the optical barrel as a substantially parallel light beam in the optical axis direction. Therefore, the configuration is simple, and the hole inner surface inspection device can be constructed at low cost. Accordingly, a great effect can be obtained for measuring the inner diameter of the cylindrical hole in the cylinder block or the like.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a hole inner surface inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a positional relationship between a convergence position of a light beam by an objective lens and an object to be measured (an inner surface of a hole).

FIG. 3 is a diagram schematically showing a concept of an amplitude method for detecting focus while continuously changing a focus position.

FIG. 4 is a schematic configuration diagram of a hole inner surface inspection apparatus according to another embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a hole inner surface inspection apparatus according to still another embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a hole inner surface inspection apparatus according to another embodiment of the present invention.

FIG. 7 is a diagram schematically showing how a light receiving pattern obtained via a cylindrical lens changes in the hole inner surface inspection apparatus shown in FIG. 6;

FIG. 8 is a diagram illustrating a relationship between a difference between a light receiving amount in a vertical direction and a horizontal direction of a light receiving pattern obtained via a cylindrical lens and a deviation from a focus position.

FIG. 9 is a schematic configuration diagram of a conventional optical inner diameter measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 20 Optical lens barrel 21 Reflecting mirror 22 Objective lens 23 Relay lens 30 Optical unit 31 Condensing lens 32 Light source 33 Actuator 34 Beam splitter 36 Light receiving device 37 Focus detection part 38 Lens drive mechanism 39 Data processing device

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[Procedure amendment]

[Submission date] May 21, 2001 (2001.5.2)
1)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0003

[Correction method] Change

[Correction contents]

[0003]

Therefore, recently, the focusing position is changed using the longitudinal magnification of an optical system (lens) for irradiating the object to be measured with light, and the optical axis of the lens is changed according to the information of the focal point. A method (confocal method) of measuring the inner diameter of a cylindrical hole by calculating the distance between the lens and the object to be measured from the displacement in the direction has been proposed. This type of apparatus generally condenses a light beam emitted from a light source 1 through an objective lens (condensing lens) 2 and guides it into an optical lens barrel 3 as shown in FIG. After irradiating the inner surface 5 of the cylinder to be measured through the reflecting mirror 4 provided at the tip of the cylinder 3 and condensing the reflected light coaxially with the light beam through the objective lens 2, the reflected light is It is configured to guide the light to the light receiver 7 via the beam splitter 6. Then, the focus detecting unit 8 detects a shift in the focal position of the light beam irradiated on the inner surface 5 of the cylinder from a change in a light receiving pattern of the light reflected by the light receiver 7 and drives the lens driving mechanism 9 to drive the objective lens. 2 is displaced in the direction of the optical axis to adjust the focus position (focus adjustment) of the light beam with respect to the inner surface 5 of the cylinder. Then, the distance between the objective lens 2 and the inner surface 5 of the cylinder and the distance between the optical center where the reflecting mirror 4 is provided and the inner surface 5 of the cylinder are obtained from the displacement amount of the objective lens 2.

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Fig. 9

[Correction method] Change

[Correction contents]

FIG. 9

Continuation of the front page F term (reference) 2F065 AA06 AA27 AA49 BB08 DD03 FF10 HH04 HH13 LL00 LL04 LL08 LL12 LL62 MM16 QQ30 UU01

Claims (10)

[Claims] 1. A hole inner surface inspection apparatus, comprising: an optical barrel inserted into a hole of an object to be measured, and optically inspecting an inner surface of the hole of the object to be measured through the optical barrel. An optical system that introduces light emitted from the optical column into the optical column; a relay lens that guides the light that is introduced into the optical column into the optical column as a light beam that forms a substantially parallel light beam; and the optical column. A reflecting mirror provided at the tip of the light beam to bend the optical axis of the light beam in a direction perpendicular to the light beam; and converging the light beam bent or bent by the reflecting mirror to irradiate the inner surface of the hole of the object to be measured. An objective lens that condenses the reflected light coaxially with the light beam and introduces the reflected light into the optical column in a reverse direction; and displacing the relay lens in the optical axis direction to move the relay lens from the object to be measured. The focus position of the light applied to the inner surface of the hole A focus adjusting mechanism, which is provided between the light source of the optical system and the relay lens, and separates reflected light guided in the opposite direction through the optical lens barrel from light emitted from the light source. A splitter; a light receiver for receiving the reflected light separated by the beam splitter and detecting a focus state of a light beam emitted from the objective lens to the inner surface of the hole of the object to be measured; and the reflected light. A hole measuring device for measuring a distance between the objective lens and a hole inner surface of the object to be measured from a displacement amount of the relay lens when a focusing state is detected from the hole inner surface inspection device. . 2. An apparatus for inspecting an inner surface of a hole, comprising: an optical barrel inserted into a hole of the object to be measured, and optically inspecting the inner surface of the hole of the object to be measured through the optical barrel. A light source that outputs a beam, a condenser lens that collects the light beam and introduces the light beam into the optical column, and converts the light introduced into the optical column by the condenser lens into a substantially parallel light beam. A relay lens for guiding the inside of the optical barrel; a reflecting mirror provided at the tip of the optical barrel for bending an optical axis of a light beam guided in the optical barrel at a right angle; and an optical axis via the reflecting mirror. Is bent or bent, and the light beam is converged and irradiated on the inner surface of the hole of the object to be measured, and the reflected light is condensed coaxially with the light beam and introduced into the optical column in the opposite direction. An objective lens, the condenser lens or the relay lens A focus adjustment mechanism that displaces the light in the optical axis direction to change a focal position of light emitted from the objective lens to the inner surface of the hole of the object to be measured; and a focus adjustment mechanism provided between the light source and the condenser lens. A beam splitter for separating reflected light guided in the opposite direction through the optical lens barrel from light output from the light source; and receiving the reflected light separated by the beam splitter and irradiating the reflected light from the objective lens. A light detector for detecting a focused state of the light beam on the inner surface of the hole of the object to be measured, and the objective lens based on a displacement amount of the condenser lens or the relay lens when the focused state is detected from the reflected light. And a distance measuring means for measuring a distance between the object and the inner surface of the hole. 3. The hole inner surface inspection apparatus according to claim 1, wherein the reflection mirror is rotatably provided around an optical axis of a light beam formed by the relay lens as a rotation axis. 4. The hole inner surface inspection apparatus according to claim 1, wherein the focus adjustment mechanism displaces the relay lens according to a focus state of reflected light detected by the light receiver. 5. The hole inner surface inspection apparatus according to claim 2, wherein the focus adjustment mechanism displaces the condenser lens according to a focus state of reflected light detected by the light receiver. 6. The focus adjusting mechanism repeatedly displaces the relay lens with a predetermined displacement width, wherein the distance measuring means is configured to detect the in-focus state from the reflected light. The hole inner surface inspection apparatus according to claim 1, wherein the displacement amount is taken as information on a distance between the objective lens and a hole inner surface of the object to be measured. 7. The focus adjusting mechanism repeatedly displaces the condensing lens with a predetermined displacement width, and the distance measuring means is configured to detect the focus when a focused state is detected from the reflected light. 3. The hole inner surface inspection apparatus according to claim 2, wherein the displacement amount of the optical lens is taken in as information on the distance between the objective lens and the hole inner surface of the object to be measured. 8. The collimator according to claim 2, wherein the condenser lens has a collimator optical system formed between the condenser lens and the light source, and the beam splitter is incorporated in the collimator optical system. Hole inner surface inspection device. 9. An apparatus for inspecting an inner surface of a hole which optically inspects an inner surface of a hole of the object to be measured through the optical lens barrel, the apparatus comprising: an optical barrel inserted into a hole of the object to be measured; An optical system that introduces light emitted from the optical column into the optical column; a relay lens that guides the light that is introduced into the optical column into the optical column as a light beam that forms a substantially parallel light beam; and the optical column. A reflecting mirror provided at the tip of the light beam to bend the optical axis of the light beam in a direction perpendicular to the light beam; and converging the light beam bent or bent by the reflecting mirror to irradiate the inner surface of the hole of the object to be measured. An objective lens that condenses the reflected light coaxially with the light beam and introduces the reflected light into the optical barrel in a reverse direction; and an optical lens provided between the light source of the optical system and the relay lens. The reflected light guided in the opposite direction through the light source A beam splitter for separating the emitted light, a light receiver for receiving the reflected light separated by the beam splitter, and a light receiving pattern of the reflected light obtained by the light receiver for analyzing a hole of the object to be measured. Distance measuring means for detecting a shift amount of a light beam applied to an inner surface from a focused state, and obtaining a distance between the objective lens and an inner surface of the hole of the object to be measured based on the shift amount; A hole inner surface inspection apparatus, characterized in that: 10. The light receiving device includes a light receiving region divided into four parts for receiving the reflected light via a cylindrical lens, wherein the distance measuring means includes a light receiving region in each light receiving region of the light receiving device. A change in the light receiving pattern of the reflected light is detected from the amount of received light, and a reference is made to a table in which the relationship between the amount of change in the light receiving pattern and the amount of deviation of the light beam from the in-focus position is stored in advance. The hole according to claim 9, wherein a shift amount from a focus position is obtained, and the shift amount is added to a focusing distance of the objective lens to obtain a distance between the objective lens and an inner surface of the hole of the object to be measured. Inner surface inspection device.