JP2003322504A - Interference microscope - Google Patents

Abstract

(57) [Summary] The present invention aims at simplifying the handling operation, realizing promotion of high sensitivity, and realizing diversification of usage forms. is there. A light emitted from a light source is split into two lights having different polarization directions, and one of the lights is irradiated on a sample, and a sample light having information on the sample is obtained. The other side of the sample light is matched with the reference light as the other light, and the angle of the polarization plane of the matched light is set to the liquid crystal element 17.
The structure was designed so that interference light having arbitrary phase information can be obtained by variably controlling the target, thereby achieving the intended purpose.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interference microscope used for measuring the surface shape, temperature distribution, refraction distribution, etc. of a sample such as a precision processed product.

[0002]

2. Description of the Related Art In the field of measurement, the surface shape of a sample,
As a means for measuring temperature distribution, refraction distribution, etc., sample light obtained by irradiating the sample with one of two lights with different polarization directions, and the other light as reference light are used to generate interference light. There is known a polarization interferometer that detects a phase shift of interference light with high accuracy and at high speed. An example of such a polarization interferometer is Japanese Patent No. 2821685 (Japanese Patent Laid-Open No. 2-222).
87107) and those disclosed in Japanese Patent Application Laid-Open No. 9-281441.

However, in the above-mentioned polarization interferometer, both of them are provided with three photo-detecting elements to measure the interference light, so that the respective timings are synchronized with each other and each alignment is within 1 pixel. If the setting is not made, it is difficult to perform highly accurate measurement, so that there is a disadvantage that the handling operation including the adjustment work is very troublesome.

Further, both of the above-mentioned devices have three photodetectors, so that the intensity of light becomes 1/3, so that it is difficult to improve the S / N ratio. Also has.

Further, both of the above proposed methods have a disadvantage that it is difficult to diversify the specifications because the phase information is limited to three types at the maximum.

[0006]

As described above, in the conventional polarization interferometer, the handling operation including the adjustment work is troublesome, it is difficult to improve the sensitivity, and the usage pattern is restricted. It has the inconvenience of having.

The present invention has been made in view of the above circumstances, and it is possible to realize the promotion of high sensitivity and the diversification of usage forms while simplifying the handling operation. The purpose of the present invention is to provide an interference microscope.

[0008]

According to the present invention, light emitted from a light source is branched into two different polarization directions, one of the lights is irradiated to a sample, and sample light having information of the sample is obtained. The sample light is matched with the other branched light to generate interference light, and in an interference microscope that measures this interference light, a liquid crystal element that sets the angle of the polarization plane of the interference light,
An interference microscope was configured by including a control unit that controls the amount of voltage applied to the liquid crystal element to control the angle of the polarization plane.

According to the above structure, when the voltage applied to the liquid crystal element is changed by the control means, the angle of the plane of polarization of the matched light is variably set according to the amount of the voltage, and the liquid crystal element is set to an arbitrary value. Acquiring interference light having phase information. As a result, it is possible to easily realize high-sensitivity measurement with a simple operation of controlling the amount of voltage applied to the liquid crystal element while realizing various measurement usage forms.

Further, the present invention comprises an image pickup camera for taking an image of the interference light whose polarization plane angle is controlled through the liquid crystal element. According to this, it becomes possible to compare and examine the coherent light having a variable phase captured by the image pickup camera, and it is possible to diversify the measurement and use form.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows an interference microscope according to an embodiment of the present invention. A branching half mirror 11 is arranged on the optical path of a light source 10. This branch half mirror 11
Splits the light emitted from the light source 10 into two light beams having different polarization directions (X, Y) which are different from each other by approximately 90 degrees, and
First and second total reflection mirrors 1 arranged on the exit optical path of
Distribute into 2 and 13.

Then, a matching half mirror 14 is provided on the outgoing optical paths of the first and second total reflection mirrors 12 and 13.
Are arranged so that their first and second incident light paths face each other. Further, for example, a stage (not shown) on which the sample 15 is mounted is arranged on the optical path between the first total reflection mirror 12 and the matching half mirror 14.

A quarter-wave plate 16, a liquid crystal element 17, and a polarizing plate 18 are arranged in this order on the outgoing optical path of the matching half mirror 14, and a television (TV) as an image pickup camera is provided behind the polarizing plate 18. A camera 19 is arranged. In the matching half mirror 14, the light guided to the first total reflection mirror 12 is guided to the first incident optical path, and the stage (not shown).
Sample 1 generated by irradiating sample 15 mounted on top
The sample light having the information of No. 5 is guided, and the reference light, which is the reference light guided to the second total reflection mirror 13, is guided to the second incident optical path of the sample light, and the sample light and the reference light are separated from each other. The signals are superimposed and output to the quarter-wave plate 16.

As shown in FIG. 2, the quarter-wave plate 16 converts linearly polarized light obtained by superimposing the sample light and the reference light from the matching half mirror 14 into circularly polarized light and polarization through the liquid crystal element 17. Output to the plate 18. The polarizing plate 18 converts circularly polarized light input through the liquid crystal element 17 into linearly polarized light again,
This linearly polarized light is projected on the TV camera 19 and taken as interference light.

The liquid crystal element 17 is connected to a control unit 20, and the applied voltage is variably controlled via the control unit 20. When a voltage is applied by the controller 20 to the liquid crystal element 17, the liquid crystal array is rotated according to the amount of the voltage and the rotation angle is variably controlled, and according to the rotation angle, the quarter-wave plate 1
The angle of the polarization plane (phase) of the circularly polarized light guided through 6 is variably set. When the voltage is not applied, the liquid crystal element 17 does not change the rotation angle of the liquid crystal array, and thus directly changes the polarization angle of the circularly polarized light from the quarter-wave plate 16 without changing the polarization angle. , To the polarizing plate 18 in the subsequent stage.

In the above structure, when acquiring the phase information of the sample 15, the sample is mounted on the stage (not shown) and the light source 10 is driven to emit light. Then, the light emitted from the light source 10 is split into two lights having different polarizations by the split half mirror 11, and is guided to the first and second total reflection mirrors 12 and 13. The light guided to the first total reflection mirror 12 among them is the sample 1 on the stage (not shown).
The sample light having the information of the sample 15 is irradiated to the beam No. 5 and guided to the first incident optical path of the matching half mirror 14.

On the other hand, the light guided to the second total reflection mirror 13 is directly referred to as the reference light and the matching half mirror 14 is used.
Is guided to the second incident optical path. Matching half mirror 14
Superimposes the light guided to the first and second incident light paths,
The superimposed light is output to the quarter-wave plate 16. 1/4
The wave plate 16 converts the input linearly polarized light into circularly polarized light and outputs the circularly polarized light to the liquid crystal element 17.

Here, a desired voltage is applied to the liquid crystal element 17 via the control section 20, the alignment of the liquid crystal is rotationally controlled according to the applied voltage, and the quarter wavelength plate 16 is controlled according to the rotation angle. The angle of the polarization plane of the circularly polarized light input via is changed and output to the polarizing plate 18. The polarizing plate 18 projects the interference light generated by converting the input circularly polarized light whose polarization plane angle is controlled into linearly polarized light onto the TV camera 19. Here, the TV camera 19 acquires the image data of the interference light having the desired phase information.

At this time, the control section 20 variably controls the voltage applied to the liquid crystal element 17 to change the alignment of the liquid crystal of the liquid crystal element 17 and the light converted into the circularly polarized light by the ¼ wavelength plate 16. The angle of the plane of polarization is variably controlled. The light whose polarization plane angle is variably controlled by the liquid crystal element 17 is transmitted through the polarizing plate 1
8 converts the linearly polarized light into interference light having different phase information according to the angle of the plane of circular polarization, and the interference light having different phase information is generated by the TV camera 1
It is acquired as image data in 9. This TV camera 19
The desired measurement of the temperature distribution, the refraction distribution, and the like of the sample 15 is performed based on the image data of the interference light having different phase information photographed in.

The liquid crystal element 17 has a control section 20.
When no voltage is applied, the rotation angle of the liquid crystal array is kept in the initial state as described above, and the quarter wavelength plate 1
The incident circularly polarized light is directly output to the polarizing plate 18 without changing the angle of the plane of polarization of the light from 6. As a result, the polarizing plate 18 generates interference light in which the angle of the polarization plane of the light superposed by the matching half mirror 14 is kept in the initial state, and this interference light is projected onto the TV camera 19 as image data. To be acquired.

As described above, the interference microscope includes the light source 10
The emitted light is split into two lights with different polarization directions,
The sample 15 is irradiated with the one light, the sample light having the information of the sample 15 is acquired, and the other branched light is matched with the sample light as the reference light. The angle of the plane of polarization is variably controlled using the liquid crystal element 17,
The interference light having arbitrary phase information can be acquired.

According to this, by variably controlling the voltage applied to the liquid crystal element 17, the angle of the plane of polarization of the matched light is variably set according to the voltage amount, and the interference having arbitrary phase information is obtained. Since the light can be acquired only by providing one TV camera 19, it is possible to easily realize high-sensitivity measurement while realizing various measurement usage modes with a simple configuration.

Further, according to this, since it becomes possible to acquire the interference light having arbitrary phase information, it can be applied to various interferometers, and any interferometer realizes highly sensitive measurement. It becomes possible.

A reflection type microscope system equipped with an interference microscope, which is a feature of the present invention, will be described with reference to FIG. However, in FIG. 3, the same parts as those in FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

That is, the output optical path of the beam splitter 21 which constitutes the reflection type microscope system is arranged to face the incident optical path of the quarter wavelength plate 16. A light source 23 is arranged to face the incident light path of the beam splitter 21 via a collimator lens 22, and a sample 25 is arranged to the reflection light path thereof via a quarter-wave plate 24.

Further, a reference mirror 27 is arranged in the transmission optical path of the beam splitter 21 so as to face it, with a quarter wavelength plate 26 interposed therebetween.

With the above structure, the constraint emitted from the light source 23 is set into parallel light by the collimator lens 22 and is incident on the beam splitter 21, and is separated into linearly polarized light whose polarization directions differ by 90 °. A reflected light path and a transmitted light path are guided. One of the linearly polarized lights guided to the reflection optical path is guided to the quarter-wave plate 24, converted into circularly polarized light, and applied to the sample 25, and again as sample light having information of the sample 25. The beam is guided to the quarter-wave plate 24 and is converted again into linearly polarized light.
Be led to.

On the other hand, the other linearly polarized light guided to the transmission optical path is guided to the quarter-wave plate 26, converted into circularly polarized light, and applied to the reference mirror 27. The light is guided to the / 4 wavelength plate 26, converted again into linearly polarized light, and guided to the beam splitter 21. Then, the beam splitter 21 superimposes the incident sample light and reference light to generate interference light, and emits the interference light from the output optical path to the quarter-wave plate 16 constituting the interference microscope.

Here, as described above, the quarter-wave plate 16
Converts the input linearly polarized light into circularly polarized light and outputs the circularly polarized light to the liquid crystal element 17. At this time, a desired voltage is applied to the liquid crystal element 17 via the control unit 20, the alignment of the liquid crystal is rotationally controlled according to the applied voltage, and 1
The angle of the plane of polarization of the circularly polarized light input via the / 4 wavelength plate 16 is changed and output to the polarizing plate 18. The polarizing plate 18 is
Interference light generated by converting the input circularly polarized light whose polarization plane angle is controlled into linearly polarized light is projected onto the TV camera 19. Here, the TV camera 19 acquires the image data of the interference light having the desired phase information.

As described above, a simple operation of equipping the reflection type microscope system and variably controlling the voltage applied to the liquid crystal element 17 can measure, for example, a slight step of a metal surface that does not transmit light. It can be measured with high accuracy.

In the above embodiment, the TV camera 1
The case where the interference light is taken in using 9 is explained, but the present invention is not limited to this, and it is also possible to use other imaging cameras.

Further, in the above embodiment, an optical system in which the sample light and the reference light are superposed by using the split half mirror 11, the first and second total reflection mirrors 12 and 13, and the matching half mirror 14 is provided. Although the case of using the optical system has been described, the present invention is not limited to this optical system and can be configured.

Therefore, the present invention is not limited to the above-described embodiment, and in addition, various modifications can be carried out at the stage of carrying out the invention without departing from the spirit thereof. Further, the embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements.

For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, the problem described in the section of the problem to be solved by the invention can be solved, and the effect described in the effect of the invention can be obtained. When the above is obtained, the configuration in which this constituent element is deleted can be extracted as the invention.

[0036]

As described in detail above, according to the present invention, the handling operation can be simplified, the sensitivity can be promoted, and the usage patterns can be diversified. The interference microscope can be provided.

[Brief description of drawings]

FIG. 1 is a configuration explanatory view showing an arrangement configuration of an interference microscope according to an embodiment of the present invention.

FIG. 2 is a configuration diagram shown for explaining an operation of a main part of FIG.

FIG. 3 is a configuration diagram showing an arrangement configuration when the reflection microscope system is equipped with FIG.

[Explanation of symbols]

10 ... Light source 11… Branch half mirror 12 ... First total reflection mirror 13 ... Second total reflection mirror 14… Matched half mirror 15… Sample 16 ... Quarter wave plate 17 ... Liquid crystal element 18 ... Wave plate 19 ... TV camera 20 ... Control unit 21… Beam splitter 22 ... Collimator lens 23 Light source 24, 26 ... Quarter wave plate 25… Sample 27 ... Reference mirror

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/13 101 G02F 1/13 101 1/1335 510 1/1335 510 F term (reference) 2F064 AA09 CC10 EE01 GG12 GG22 GG33 GG38 GG44 HH03 HH08 HH09 2H052 AA04 AB24 AB26 AC01 AF01 AF14 2H088 EA47 HA15 HA17 HA18 HA20 HA22 HA28 MA20 2H091 FA10Z FA11Z FA12Z FA15Z FA41Z FA48X GA11 LA30 MA10

Claims (2)

[Claims] 1. A light emitted from a light source is branched into two different polarization directions, one of the lights is irradiated to a sample, sample light having information on the sample is acquired, and the sample light is branched. In the interference microscope that generates interference light by matching the other light with the other light and measures the interference light, the liquid crystal element that sets the angle of the polarization plane of the interference light and the voltage amount applied to this liquid crystal element are controlled. And a control means for controlling the angle of the polarization plane. 2. The interference microscope according to claim 1, further comprising an imaging camera for photographing the coherent light whose polarization plane angle is controlled via the liquid crystal element.