JP2003254708A - Method of measuring correction value - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measuring method in which the correction value for a dimension-measured value with an end standard can be easily found by a light wave interference method. <P>SOLUTION: This correction value measuring method is provided with a process (S10) for bringing close contact for ringing in parallel one end face 12a of a reference end standard for light reflection, and generating no phase change in the light reflection, and one end face 14a of the measuring end standard, onto a light transmitting base plate 10a, a phase shift acquiring process (S14) for making interfering light 38 incident into a plate 10 from a non-ringing face 10b, for making a transmitting light thereof incident on the end ringing side end faces 12a, 14a from the orthogonal direction thereof, for forming reference interference light by reflected light from the reference end standard 12a, and for forming measuring interference light by reflected light from the end standard 14a, so as to find a phase shift between an interference fringe 42 by the reference interference light and an interference fringe 44 by the measuring interference light, and a correction value acquiring process for obtaining a phase variation of the end standard 14 based on the phase shift. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a correction value measuring method, and more particularly to a measuring method capable of easily obtaining a correction value for a dimension measurement value of an end device by light wave interferometry.

[0002]

2. Description of the Related Art Conventionally, an end device has been used as a length standard. The end gauge is a standard that expresses a specified dimension by the face-to-face distance between both ends, and a gauge block is a typical one. This gauge block has extremely high dimensional accuracy,
The measurement surface easily adheres (rings) to the measurement surface of another gauge block. Therefore, the combined size obtained by closely contacting several gauge blocks is equal to the sum of the sizes of the individual gauge blocks, and the required size is obtained. On the other hand, since this gauge block is used such that the measuring surface is always in contact with other measuring surfaces, it is apt to be scratched or worn, and the materials are subject to aging. Therefore, regular inspection is required. Therefore, conventionally, there is a method of measuring the dimension between the end faces of the gauge block which face each other using an optical wave interference measuring device (for example, Japanese Patent Laid-Open No. 8-2716224). By inserting a gauge block into the optical path of such a light wave interferometer, it is possible to measure the dimension between the end faces of the end device facing each other without contact.

[0003]

By the way, the size of the end protractor is determined with extremely high accuracy, and the length measurement for inspecting the size requires higher accuracy.
However, even with the above-mentioned light wave interferometry, it is excellent in that the measurement can be performed in a non-contact manner, but it is difficult to completely eliminate the error of the measurement value. Therefore, it is necessary to correct the measurement value obtained by the light wave interferometry, but conventionally, there is no technique for easily measuring the correction value for the measurement value, and therefore, there is only one representative value for the measurement values of all gauge blocks. It was corrected by the value.

However, it is considered that the error of the measurement value by the light wave interferometry differs depending on, for example, the lot or the individual end device, and if one representative value is used for the measurement values of all end devices, It becomes difficult to inspect the size of the protractor with high accuracy. Then, in order to improve the accuracy of the dimension measurement of the end device, there has been an urgent need to develop a technique capable of easily obtaining a correction value. The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to provide a correction value measuring method capable of easily obtaining a correction value for a dimension measurement value of an end device by the light wave interferometry. .

[0005]

When optical wave interferometry is used for measuring the size of an end device, the surface roughness of the measurement end face of the end device and the complex refractive index due to the material of the end device affect the end device. It is known that the reflected light on the measurement end face causes a phase change. Therefore, when the light wave interferometry is used, the measured value of the size of the end device becomes shorter than the mechanical length, that is, the actual length. The magnitude of this amount of phase change has a great influence on the accuracy of the size measurement of the end device.When using the light wave interferometry, by adding the amount of phase change as a correction value to the measured value, We have come to the knowledge that it is necessary to make the length appropriate. That is, in order to achieve the above object, the correction value measuring method according to the present invention comprises a light emitting means,
A method of measuring a phase change amount, which is a correction value for a dimension measurement value between opposed end faces of an end device by an optical wave interferometer including a half mirror and a reference mirror, including a contacting step and an arranging step. And a phase shift acquisition step and a correction value acquisition step.

Here, in the contacting step, one end surface of a reference end device for reflecting light and causing no phase change at the time of reflecting the light, and a phase at the time of reflecting the light with respect to the reference plane of the base plate for transmitting the light. Ring one end face of the measuring end device that will change, in parallel, and use it as the measurement work. It is ideal that the phase change does not occur at all, but it means that the phase change is extremely small to the extent that the dimension measurement is not adversely affected. In the arranging step, a non-ringing surface facing the reference plane of the base plate faces the half mirror, and a ringing side end surface of the reference end protractor and a ringing side end surface of the measuring end protractor are the half mirrors. The measurement work is arranged in the optical path of the light wave interference measuring apparatus so as to be orthogonal to the optical axis of.

In the phase shift acquisition step, the parallel coherent light from the light emitting means is split into two by the half mirror, and the first split light from the half mirror is returned to the half mirror again by the reference mirror. Then, the second split light from the half mirror is made incident from the non-ringing surface of the base plate, and the transmitted light of the base plate is applied to the ringing side end surface of the reference end device and the ringing side end face of the measuring end device. The reference reflected light from the ringing side end face of the reference end protractor and the measurement reflected light from the ringing side end face of the measuring end protractor are returned to the half mirror through the base plate, The half mirror forms reference interference light with the reference reflected light from the reference end device and the reflected light from the reference mirror, and the measurement reflected light from the measurement end device and the reference mirror. To form a measured interference light in reflected light,
Reference interference fringes due to reference interference light from the half mirror,
Also, the measurement interference fringes due to the measurement interference light are detected, and the phase shift between the reference interference fringes and the measurement interference fringes is obtained.

In the correction value acquisition step, the phase change amount of the measuring end device is obtained based on the phase deviation obtained in the phase deviation acquisition step. In addition, in the present invention, it is preferable that the correction value acquisition step obtains the phase correction amount from the following Expression 2.

Where δ is the phase correction amount, m is a constant based on the complex index of refraction of the measuring end protractor, and b / a is Phase shift obtained in the phase shift acquisition step

Further, in the present invention, the reference end gauge is
It is preferable that at least the ringing side end face is smooth so that no phase change occurs when light is reflected by the ringing side end face. Further, in the present invention, it is preferable that the reference end protractor has a complex refractive index that does not cause a phase change when light is reflected on the ringing end face. Further, in the present invention, it is preferable that the material of the base plate and the reference end device is any one of synthetic quartz and borosilicate glass.

In this optical glass, crystals are regularly arranged, and there is little noise during light transmission. Therefore, the material of the base plate which is required to transmit the incident light to the end device and the reflected light from the end device. As is very good. Moreover, this optical glass has a complex index of refraction determined, and it becomes certain and easy to select the complex index of refraction of the reference end device so as not to cause a phase change during reflection.
It is also an excellent material for the reference end device. Among such optical glasses, synthetic quartz has good light transmittance in the ultraviolet and visible regions, and borosilicate glass has a wavelength of 350 nm to
Since it has a good light transmittance at 1600 nm, it is particularly preferable as a material for the base plate and the reference end device of the present invention.

Further, in the present invention, it is preferable that the non-ringing surface of the base plate is inclined at a predetermined angle with respect to the direction orthogonal to the optical axis of the second split light from the half mirror. In particular, the angle of inclination of the non-ringing surface of the base plate is such that the reflected light on the non-ringing surface does not return to the half mirror, and the transmitted light of the base plate is the ringing side end surface of the reference end device and the measurement end degree. It is preferable that the angle of incidence is on the ringing side end surface of the container from a direction substantially orthogonal to the end surface. The inclination angle of the non-ringing surface is set to a very small angle within a range in which the purpose of preventing reflected light on the non-ringing surface, which causes interference fringe noise, from returning to the half mirror.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration in which a measurement work is arranged in an optical path of an optical wave interferometer for performing a correction value measuring method according to an embodiment of the present invention. In the present embodiment, an example will be described in which a Twyman-Green interferometer is used as a light wave interference measuring device and a phase change amount of a gauge block is measured as an end device. First, a contact process (S10) is performed. That is, with respect to the reference plane 10a of the base plate 10 for transmitting light,
One end surface 12a of a reference gauge block (reference end gauge) 12 for light reflection and that does not cause a phase change at the time of the light reflection, and one end surface 14a of a measurement gauge block (measurement end gauge) 14.
Are ringed in parallel to form a measurement work 16.

After the contact step (S10), the measurement work 16 is placed in the optical path of the light wave interference measuring device 18 (arrangement step S12). That is, the light wave interference measuring device 18 is
Light emitting means 20, half mirror 22, and reference mirror 24
And a screen 26. In the arranging step S12, the non-ringing surface 10b of the base plate 10 facing the standard plane 10a faces the half mirror 22, and the ringing side end surface 12a of the reference gauge block 12 and the ringing side end surface 14a of the measurement gauge block 14 are arranged.
However, the measurement work 16 is arranged so as to be orthogonal to the optical axis of the half mirror 22.

After the placement step (S12), a phase shift acquisition step (S14) is performed. The light emitting means 20 includes, for example, a laser 28 and a collimator lens 30. The laser 28 emits laser light (coherent light) 32. The collimator lens 30 converts the laser light 32 from the laser 28 into parallel light 34. The half mirror 22 splits the parallel light 34 from the lens 30 into a first split light 36 and a second split light 38. The first split light 36 from the half mirror 22 is received by the reference mirror 24, and the reflected light 40 is returned to the half mirror 22 again. On the other hand, the second split light 38 from the half mirror 22 enters the measurement work 16.

That is, the second split light 38 from the half mirror 22 is applied to the base plate 1 from the non-ringing surface 10b.
It is incident on 0. The incident light passes through the base plate 10 and the end surface 12 of the reference gauge block 12 on the ringing side.
a and the ringing side end surface 14a of the measurement gauge block 14 is incident in a direction orthogonal to the a. Reference reflected light from the ringing side end surface 12a of the reference gauge block 12, and the ringing side end surface 1 of the measurement gauge block 14.
The measurement reflected light from 4a passes through the base plate 10 and is returned to the half mirror 22.

The half mirror 22 forms reference interference light with the reference reflected light from the reference gauge block 12 and the reflected light 40 from the reference mirror 24, and the measurement reflected light from the measurement gauge block 14 and the reflection from the reference mirror 24 are formed. The light 40 forms the measurement interference light. Reference interference fringes 42 due to the reference interference light from the half mirror 22 and measurement interference fringes 4 due to the measurement interference light.
4 is formed on the screen 26. Therefore, the work-side optical path L1 is formed by the laser 28 → lens 30 → half mirror 22.
→ base plate 10 → reference gauge block 12 and measurement gauge block 14 → base plate 10 → half mirror 22 → screen 26. On the other hand, the reference side optical path L
2, the laser 28 → lens 30 → half mirror 22 → reference mirror 24 → half mirror 22 → screen 26.

Then, in the phase shift acquisition step (S14), the value of the phase shift between the reference interference fringes 42 and the measurement interference fringes 44 formed on the screen 26 is obtained by using, for example, visual measurement or a ruler. Based on the phase shift value, the amount of phase change of the gauge block 14 is determined by the subsequent correction value acquisition step. Here, a characteristic of this embodiment is that the light reflection reference gauge block 12 and the measurement gauge block 14 are ringed in parallel with the light transmission base plate 10. As shown in the figure, the non-ringing surface 10b of the base plate 10 faces the half mirror 22 and the ringing side end surface 1 of the reference gauge block 12 is in the optical path of the light wave interference measuring device 18.
2a and the ringing side end surface 14a of the measurement gauge block 14 are arranged so that the measurement work 16 is orthogonal to the optical axis of the half mirror 22, so that the phase change amount of the measurement gauge block 14 can be directly measured by one time. I have been there.

Here, the base plate 10 is made of a light-transmissive material such as synthetic quartz or borosilicate glass such as SCHOTT.
Composed of any optical glass material such as BK7, a product name of GLAS. The base plate 10 has a predetermined complex refractive index, and at least the reference plane 10a has a very small surface roughness. The base plate 10 also has a non-ringing surface 1 which causes interference fringe noise.
In order to prevent reflection from 0b, the non-ringing surface 10
b is slightly inclined with respect to the direction orthogonal to the optical axis of the half mirror 22 on the work side.

This inclination is set to a small angle at which the light reflection of the second split light 38 on the non-ringing surface 10b does not return to the half mirror 22. Moreover, the angle of this inclination is such that the second split light 38 from the half mirror 22 is
When entering from the non-ringing surface 10b of 0, it is refracted by the inclination of the non-ringing surface 10b, and the gauge block 1
The ringing side end surfaces 12a of the reference gauge block 12 are incident even when the light is incident from an angle inclined from a direction orthogonal to the ringing side end surfaces 12a and 14a of the reference gauge blocks 12.
The angle at which the refraction of light is extremely small is set to an extent that the light reflection at 1 is favorably generated without adversely affecting the measurement of the phase change amount.

The inclination angle of the non-ringing surface 10b is a minute angle of about 1 degree at most even if it is large. For example, if the inclination angle of the non-ringing surface 10b is 1, the refractive index of air is 1, and the complex refractive index of the base plate 10 is 1.5, the second division by the half mirror 22 in the direction orthogonal to the non-ringing surface 10b. Using the law of refraction, the angle of the incident optical axis of the light 38 can be obtained as an angle of 1.5 degrees.
As a result, the optical axis of the reflected light on the non-ringing surface 10b can be shifted by 3 degrees with respect to the incident optical axis.
The light reflected by the non-ringing surface 10b is reflected by the half mirror 22.
It is possible to prevent the light from returning to. As a result, in the present embodiment, the cause of the interference fringe noise can be significantly reduced, so that the light wave interference measurement can be performed with high accuracy.

The reference gauge block 12 is made of an optical glass material such as synthetic quartz or borosilicate glass, similar to the base plate 10, and does not cause a phase change when the second split light 38 is reflected. The ringing side end surface 12a has a smoothness and a predetermined complex refractive index. The measurement gauge block 14 is made of any material such as steel, super-steel, and ceramic.

As described above, in this embodiment, one end surface 12a of the reference gauge block 12 made of the same optical glass and one end surface 14a of the measurement gauge block 14 made of, for example, steel are arranged in parallel with the base plate 10 made of the optical glass. Ringing is performed to obtain a measurement work 16. As shown in the figure, the base plate 10 is placed in the optical path of the light wave interference measuring device 18.
The non-ringing surface 10b of the
And the ringing side end face 12 of the reference gauge block 12
a, and the ringing side end surface 1 of the measurement gauge block 14
The measurement work 16 is arranged so that 4a is orthogonal to the optical axis of the half mirror 22.

FIG. 2 shows the measurement work 16 shown in FIG.
Part A, that is, the base plate 10 and the gauge block 1
2 and 14 are enlarged views of the ringing portion.
As shown in the figure, one end face 12 of the reference gauge block 12
a and one end surface 14a of the measurement gauge block 14 are ringed with a small amount of oil on the reference plane 10a of the base plate 10. Therefore, an adhesive layer 46 made of oil is formed between the base plate 10 and the gauge blocks 12 and 14 with a uniform thickness in the optical axis direction of the second split light 38. Therefore, the second split light 38, which is the light transmitted through the base plate 10, is simultaneously incident from the direction orthogonal to the one end face 12a of the reference gauge block 12 and the one end face 14a of the measurement gauge block 14 via the adhesion layer 46. . Then, at the one end face 14a of the measurement gauge block 14, a phase change occurs at the time of reflection of the second split light 38 at the end face 14a due to the influence of the surface roughness of the end face 14a and the complex refractive index of the material. Causes a phase change δ.

On the other hand, the reference gauge block 12 is made of the same optical glass material as that of the base plate 10, but since it is made separate from the base plate 10, the second split light 38 is in the direction orthogonal to the one end face 12a. Since it is more incident, it is reflected without being substantially transmitted. Here, since the reference gauge block 12 is made of the same optical glass material as the base plate 10 and has the smoothness of the one end face 12a that does not cause a phase change and a predetermined complex refractive index, the second split light 38 is emitted from the one end face 12a. It is reflected without causing a phase change.

Therefore, the reference gauge block 12
The optical length L3 of the reflected light 50 from the base plate 10 and the optical length L4 of the reflected light 48 from the measurement gauge block 14 between the base plate 10 and one end surfaces of the gauge blocks 12 and 14 are expressed by the following mathematical formula 3, respectively. It can be represented by 4.

[Equation 3]

[Equation 4] Here, n is the refractive index of the oil used for adhesion, and is 1.5, for example. Further, m is obtained from the complex refractive index of the surface of the material of the gauge block, and is generally 1.5 here.

Therefore, the reflected light 50 from the reference gauge block 12 and the reflected light 48 from the measurement gauge block 14 differ in optical length by the amount of L4−L3 = mδ. As a result, as shown in FIG. 3, the reference interference fringes 42 and the measurement interference fringes 44 formed on the screen 26 have a phase shift corresponding to the optical length difference (mδ). And
If the value of the phase shift between the reference interference fringes 42 and the measurement interference fringes 44 formed on the screen 26 is obtained by using, for example, a visual measuring crow, the amount of phase change of the gauge block 14 based on the obtained value of the phase shift. δ is determined in the subsequent correction value acquisition step (S16).

That is, the phase shift (b / a) between the reference interference fringe 42 and the measurement interference fringe 44 formed on the screen 26.
Can be expressed by the following expression 5 from the above expressions 3 and 4.

## EQU00005 ## b / a = L4-L3 = 1.5.delta. Therefore, the phase change amount .delta. Of the gauge block 14 can be expressed by the following equation 6.

[Equation 6] δ = (1 / 1.5) · (b / a)

As described above, in this embodiment, the reference gauge block 12 made of the same optical glass and the gauge block 14 made of steel or the like are ringed in parallel to the base plate 10 made of the optical glass to make a measurement work. The non-ringing surface 10b of the base plate 10 faces the half mirror 22, and the ringing-side end surface 12a of the reference gauge block 12 and the ringing-side end surface 14a of the measurement gauge block 14 are connected to the half mirror of this. The measurement work 16 is arranged so as to be orthogonal to the optical axis of 22. Thereby, the phase change amount δ of the gauge block 14 is directly measured from the phase shift of the interference fringes of both gauge blocks.

As a result, in the present embodiment, the phase change amount δ can be easily measured directly without being affected by the dimension measurement accuracy of the gauge block 14. Then, the dimension measurement between the opposite ends of the gauge block 14 is performed by an optical wave interferometer, and the amount of phase change δ obtained by the measuring method according to the present embodiment with respect to the dimension measurement value of the gauge block 14. Gauge block 1 by adding
The dimension 4 can be obtained with high accuracy. Therefore,
In this embodiment, it is possible to easily and accurately obtain the phase change amount δ that is the correction value for the measurement value of the gauge block dimension by the light wave interferometry.

Further, in the present embodiment, the reference gauge block 12 has a smooth end face 12a so as not to cause a phase change at the time of light reflection on the ringing side end face 12a. Since it can be performed, the phase change amount δ can be obtained more accurately. Further, in the present embodiment, since the reference gauge block 12 has a complex refractive index that does not cause a phase change when light is reflected on the ringing end face 12a, the measurement by the light wave interferometry can be performed more accurately, so that the phase change amount δ You can get it more accurately.

Further, in the present embodiment, the base plate and the reference gauge block are made of synthetic quartz or borosilicate glass which has excellent homogeneity and has a predetermined complex refractive index. Since the measurement by the light wave interferometry can be performed more accurately, the phase change amount δ can be obtained accurately. Further, in the present embodiment, the non-ringing surface 10b of the base plate 10 is inclined with respect to the direction orthogonal to the optical axis of the second split light 38 from the half mirror, so that the non-ringing of the base plate 10 of the second split light 38 is performed. The reflection on the surface 10b is greatly reduced. Moreover, the returning of the reflected light on the non-ringing surface 10b to the half mirror is greatly reduced. Therefore, in the present embodiment, it is possible to prevent reflection from the non-ringing surface 10 that causes interference fringe noise, so that the measurement by the light wave interferometry can be performed more accurately. Thereby, the phase change amount δ of the measurement gauge block 14 can be accurately obtained.

Here, as a method of measuring the magnitude of the phase change amount δ of the measuring gauge block 14, in addition to the measuring method according to the present invention, a method of obtaining it from the surface roughness and the complex refractive index may be considered. As a method of obtaining from the surface roughness and the complex refractive index, for example, the surface roughness of the gauge block is measured by a surface roughness measuring device, etc., and the complex refractive index of the surface is measured by, for example, an ellipsometer, and calculated from the measured values. It is possible to find a method by

However, this method requires the use of a plurality of measuring machines such as a surface roughness measuring machine and an ellipsometer. Further, since it takes a long time for measurement, it is not suitable for many measurements, for example, a method of use such as obtaining the amount of phase change of each gauge block, and therefore it has not been adopted as a solution means of the present invention. Therefore, a method of using a base plate as shown in FIG. 4 or a method of stacking a plurality of gauge blocks as shown in FIG. 5 can be considered instead of the method of obtaining from the surface roughness and the complex refractive index.

The method using the base plate shown in FIG. 4 requires the following two measurements (a) and (b). Here, in the measurement (a), the steel gauge block 52 is ringed to the base plate 54 made of the same material as the steel gauge block 52. The gauge block 52 is arranged in the optical path of the light wave interferometer so that the gauge block 52 faces the half mirror, and the measurement surface of the gauge block 52 and the measurement surface of the base plate 54 are orthogonal to the optical axis of the half mirror. Then, the second split light 38 from the half mirror is made incident from the direction orthogonal to the measurement surface of the gauge block 52 and the measurement surface of the base plate 54, and the gate block 5 is set with the base plate 54 as a reference.
Measure 2 lengths. Let this measured value be La.

In the measurement (b), the same gauge block 52 is made of optical glass (for example, synthetic quartz, BK7, etc.).
The base plate 56 of FIG. The non-ringing surface of the gauge block 52 faces the half mirror in the optical path of the light wave interferometer, and the gauge block 52
And the measurement surface of the base plate 56 are arranged so as to be orthogonal to the optical axis of the half mirror. Then, the second split light 38 from the half mirror is made incident from a direction orthogonal to the measurement surface of the gauge block 52 and the measurement surface of the base plate 56, and the length of the gate block 52 is measured with the base plate 56 as a reference. Let this measured value be Lb. Here, in the measurement (a), there is a phase change when the second split light 38 is reflected on the measurement surface of the gauge block 52 and the measurement surface of the base plate 54.

On the other hand, in the measurement (b), only the measurement surface of the gauge block 52 changes the phase when the second split light 38 is reflected, and the measurement surface of the glass base plate 56 does not change the phase. Therefore, in the method shown in FIG. 4, the measured value of La−Lb (= (Lb + δ) −Lb =
By calculating δ), the phase change amount δ can be obtained.

In the stacking method shown in FIG. 5, the measuring principle of the method using the base plate shown in FIG. 4 is the same as in the steel gauge blocks 52A, 52.
It is expanded to B and 54C, and the phase change amount δ is obtained from the following equation 7.

[Equation 7]

However, both the method of using the base plate and the method of stacking the gauge blocks 52A, 52B, 54C require the number of measurements twice or more, and therefore require a considerably complicated operation. Moreover, since the dimensions of the gauge block are included, when measuring the dimensions of the gauge block, thermal expansion,
Fluctuation of light source wavelength and correction of that wavelength (pressure, humidity, temperature,
Dimensional changes occur due to the effects of carbon dioxide concentration).
For this reason, in the method of using the base plate and the stacking method, when measuring the amount of phase change, the accuracy is easily deteriorated due to the influence of the dimensional change of the gauge block, so in the present invention, as a method of measuring the magnitude of the phase change. It wasn't adopted.

On the other hand, in this embodiment, one end face of the same reference gauge block made of optical glass and one end face of the measurement gauge block made of steel are ringed in parallel to the reference plane of the base plate made of optical glass. The non-ringing surface facing the reference plane of the base plate faces the half mirror, and the ringing side end surface of the reference gauge block and the ringing side end surface of the measurement gauge block are
It is arranged in the optical path of the light wave interferometer to be orthogonal to the optical axis of the half mirror. As a result, in this embodiment, the phase change amount of the gauge block can be directly and easily obtained by one measurement.

Therefore, by using the measuring method according to the present embodiment, for example, the amount of phase change of each lot of gauge blocks or each gauge block is measured, and the amount of phase change is added to the dimension measurement value. The dimension of the measurement gauge block can be obtained more accurately. Moreover, in this embodiment, since the dimension of the gauge block is not included in the measurement of the phase change amount, it is possible to reliably prevent the influence of the dimension change of the gauge block. Is improved.

It should be noted that the present invention is not limited to the above-mentioned configuration, and various modifications can be made within the scope of the gist of the invention. For example, in the above configuration, the screen 26 is arranged at the rear stage of the half mirror 22, and the phase shift (b / a) of the interference fringes formed on the screen 26 is visually determined. However, the present invention is not limited to this, and instead of the screen 26, by disposing a photoelectric conversion device such as a CCD camera,
With the CCD camera or the like, the interference fringes can be photoelectrically converted and the machine can read the phase shift (b / a) of the interference fringes.

The correction value acquisition step (S16) for obtaining the phase change amount δ of the measurement gauge block 14 based on the phase deviation obtained in the phase deviation acquisition step (S14) is performed by a computer such as a computer or manually. It can be performed using any means. Further, in the above-mentioned configuration, an example in which a Twyman-Green interferometer is used as a light wave interferometer is described, but the present invention is not limited to this, and for example, a gauge block automatic light wave interferometer, a two-wavelength gauge block light wave is used. An optical wave interferometer for a gauge block, such as an interferometer or a long gauge block optical wave interferometer, can be used.

Further, the present invention is expected to be utilized in a light wave interferometer for performing a non-contact method in which the end device is arranged in the optical path without ringing the end device with respect to the base plate and the dimension thereof is measured. be able to. For example, JP-A-8
As shown in FIG. 6, the measurement work according to the present embodiment can be arranged in the optical path of the light wave interference measuring device disclosed in Japanese Patent No. 271624 to measure the phase change amount of the measurement gauge block. In the present embodiment, the parts corresponding to those in the above embodiment are denoted by reference numeral 100 and are not described.

That is, the lightwave interference length measuring apparatus 1 shown in FIG.
Reference numeral 18 denotes a laser beam 132 from the laser 128 for the lens 1
Collimated light 134 is formed by 30a and 130b. This parallel light 1
34 is split by the first half mirror 122 into first split light 136 and second split light 138. And the first split light 1
36 is incident on the reference mirror 124 via the optical wedge 180,
The reflected light 140 is returned to the half mirror 122 via the optical wedge 180. The second split light 138 is incident on the second half mirror 182. This second half mirror 182
Counterclockwise around the center of the reflection mirror 184 and the shutter 18
6 is arranged in a closed state, and the reflecting mirror 188 is arranged clockwise.

In the optical path between the reflecting mirror 188 and the shutter 186, the measuring work 118 characteristic of the present embodiment is arranged. The second split light 138 from the first half mirror 122 is reflected by the second half mirror 182 and the reflecting mirror 18.
It is incident on the measurement work 116 via 8. The reflected light is returned to the half mirror 122 via the reflecting mirror 188 and the second half mirror 182. Half mirror 122
Forms reference interference light with the reference reflected light from the reference gauge block 112 and the reflected light 140 from the reference mirror 124, and the measured reflected light from the measurement gauge block 114 and the reference mirror 12 are formed.
The reflected light 140 from 4 forms the measurement interference light.

A reference interference fringe due to the reference interference light from the half mirror 122 and a measurement interference fringe due to the measurement interference light are formed on the screen 126. If the value of the phase shift between the reference interference fringes 142 and the measurement interference fringes 144 formed on the screen 126 is obtained by using, for example, a visual measurement or a measure.
Based on the calculated phase shift value, the gauge block 114
Is determined.

When measuring the dimension between the opposite end faces of the gauge block, only the measurement gauge block 114 is arranged in the same optical path of the light wave interferometer 118 without ringing on the base plate. Further, by inserting a shutter (not shown) on the optical axis on the opposite side of the shutter 186 with the measurement gauge block 114 interposed therebetween, the shutters are arranged on both sides of the measurement gauge block 114.
Then, the dimensions of the measurement gauge blocks facing each other are obtained by changing the open / closed state of these shutters and performing dimension measurement twice. The mechanical length is obtained by adding the calculated phase change amount to the calculated optical length.

Although the measuring method according to the present invention can use any optical wave interferometer, it is possible to more easily measure the dimension between the end faces of the gauge block which face each other, and therefore, the Japanese Patent Application No. 2001 by the present applicant. It is particularly preferable to use the length measuring device of No. 3990089. This is shown in FIG. It should be noted that a part corresponding to that of the above embodiment is denoted by reference numeral
Is added and description is omitted. The light wave interference measuring apparatus 218 shown in the figure includes a laser 228, a lens 230, a reflecting mirror 290, a first half mirror 292, and an optical axis correction plate 2.
94, and a second half mirror 222a and a third half mirror 222b that have an optical axis that matches the length measurement axis of the measurement work 216 and that are arranged at a predetermined distance.

A first screen 226a and a first reference mirror 224a are arranged downstream of the second half mirror 222a. A second screen 226b and a second reference mirror 224b are disposed downstream of the second half mirror 222b.
Then, the laser light 232 from the laser 228 is passed through the lens 2
The collimated light 234 having a beam diameter of a required size is obtained by 30. The parallel light 234 from the lens 230 is reflected by the reflecting mirror 290,
It is incident on the second half mirror 222a via the first half mirror 292 and the optical axis correction plate 294. The second half mirror 222a splits the first split light 236 and the second split light 238 into two.

The first split light 236 from the second half mirror 222a is received by the first reference mirror 224a,
The reflected light 240 is returned to the half mirror 222a again. On the other hand, the second split light 238 from the second half mirror 222a is incident on the measurement work 216, and the reflected light is returned to the second half mirror 222a. The second half mirror 222a reflects the reference reflected light from the reference gauge block 212 and the reflected light 240 from the first reference mirror 224a.
To form reference interference light, and the measurement reflected light from the measurement gauge block 214 and the reflected light 240 from the first reference mirror 224a.
To form measurement interference light.

A reference interference fringe 242 due to the reference interference light from the second half mirror 222a and a measurement interference fringe 244 due to the measurement interference light are formed on the first screen 226a. If the value of the phase shift between the reference interference fringes 242 and the measurement interference fringes 244 formed on the first screen 226 is obtained using, for example, visual measurement or a ruler, the measurement gauge block is based on the obtained value of the phase shift. The phase change amount of 214 is determined.

When measuring the dimension between the opposite end faces of the gauge block, only the measurement gauge block 214 is arranged in the same optical path of the light wave interferometer 218 without ringing on the base plate, and Measure the dimensions between the opposite end faces. In the dimension measurement of the gauge block 214, preliminary measurement is performed in advance to obtain a preliminary value (preliminary dimension) with an accuracy of, for example, about 1/4 of the measurement gauge block 214. Then, the actual dimension measurement of the gauge block 214 is performed once, and the dimension between the opposing end surfaces of the measurement gauge block is obtained based on the preliminary value obtained in advance. The mechanical length is obtained by adding the obtained phase change amount to the optical length thus obtained.

[0053]

As described above, according to the correction value measuring method of the present invention, the one end face of the reference gauge block for the light reflection with respect to the light transmitting base plate and the phase change at the time of the light reflection and the measurement are performed. A contact process in which one end surface of the gauge block is ringed in parallel to form a measurement work, and coherent light is made incident on the plate from a non-ringing surface, and the transmitted light is made incident on the ringing side end surface of the gauge block in a direction perpendicular to the plate. , Reference interference light is formed by the reflected light from the reference gauge block, measurement interference light is formed by the reflected light from the measurement gauge block, and the phase shift between the interference fringes due to the reference interference light and the interference fringes due to the measurement interference light And a correction value acquisition step of obtaining the phase change amount of the measurement gauge block based on the phase shift. As a result, according to the present invention, it is possible to easily measure the amount of phase change, which is a correction value for the dimension measurement value between the opposite end faces of the end device by the light wave interferometry. Further, in the present invention, since the reference gauge block has a smooth end face so as not to cause a phase change at the time of light reflection on the ringing side end face, it is possible to perform the measurement by the light wave interferometry more accurately. You can get the quantity exactly. Further, in the present invention, since the reference gauge block has a complex index of refraction that does not cause a phase change when light is reflected at the ringing end surface, the measurement by the light wave interferometry can be performed more accurately, and thus the amount of phase change can be accurately obtained. be able to. Further, in the present invention, the material of the base plate and the reference gauge block is an optical glass that is excellent in homogeneity and has a predetermined complex refractive index, either synthetic quartz or borosilicate glass. Since the measurement by the method can be performed more accurately, the amount of phase change can be obtained accurately. Further, in the present invention, in order to prevent the reflected light from the non-ringing surface of the base plate that causes interference fringe noise from returning to the half mirror, the non-ringing surface is the light of the second split light from the half mirror. By tilting with respect to the direction orthogonal to the axis,
Since the measurement by the light wave interferometry can be performed more accurately, the phase change amount can be obtained accurately.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a schematic configuration in which a measurement work is arranged in an optical path of a light wave interferometer that performs a correction value measuring method according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a contact portion of the base plate and the end device shown in FIG.

FIG. 3 is an explanatory diagram of interference fringes obtained by the lightwave interference measurement apparatus shown in FIG.

FIG. 4 is an explanatory diagram of a general correction value measuring method.

FIG. 5 is an explanatory diagram of a general correction value measuring method.

FIG. 6 is a modification of the lightwave interference measuring apparatus that performs the correction value measuring method according to the embodiment of the present invention.

FIG. 7 is an explanatory diagram of a schematic configuration of a lightwave interference measuring apparatus suitable for performing a correction value measuring method according to an embodiment of the present invention.

[Explanation of symbols]

10 base plate 12 Reference gauge block (reference end gauge) 14 Measuring gauge block (measurement end device) 16 measurement work 18 Lightwave interferometer 20 Light emitting means 22 Half mirror 24 Reference mirror 42 Reference interference fringe 44 Measurement interference fringe

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2F064 AA00 CC01 CC10 DD10 EE02                       FF01 GG12 GG22 GG44 HH03                       HH04 HH08 JJ01                 2F065 AA22 CC00 DD04 EE00 FF52                       FF61 GG04 HH03 JJ03 JJ14                       JJ26 LL00 LL04 QQ25 QQ27

Claims (7)

[Claims] 1. A method for measuring a phase change amount, which is a correction value for a dimension measurement value between end faces of an end protractor, which is measured by a light wave interferometer including a light emitting means, a half mirror, and a reference mirror. In addition, with respect to a reference plane of a base plate for transmitting light, one end face of a reference end device for reflecting light and causing no phase change at the time of the light reflection, and a measurement that will cause a phase change at the time of the light reflection A contacting step of ringing one end face of the end device in parallel to form a measurement work, a non-ringing face that faces the reference plane of the base plate, faces the half mirror, and a ringing side end face of the reference end device, And an arranging step of arranging the measurement work in the optical path of the light wave interferometer so that the ringing side end surface of the measuring end device is orthogonal to the optical axis of the half mirror, and parallel from the light emitting means. The coherent light is split into two by the half mirror, the first split light from the half mirror is returned to the half mirror by the reference mirror, and the second split light from the half mirror is non-ringed by the base plate. Incident from the surface, the transmitted light of the base plate,
The reference reflection light from the ringing side end surface of the reference end protractor and the ringing side end surface of the measurement end protractor, and the reference reflected light from the ringing side end surface of the reference end protractor, and the measurement end protractor The reflected light measured from the end face on the ringing side is returned to the half mirror via the base plate, and the reference reflected light from the reference end device and the reflected light from the reference mirror form reference interference light in the half mirror, and Measurement interference light is formed by the measurement reflected light from the measuring end device and the reflection light from the reference mirror, and a reference interference fringe due to the reference interference light from the half mirror and a measurement interference fringe due to the measurement interference light are detected. Then, a phase shift acquisition step of obtaining a phase shift between the reference interference fringe and the measurement interference fringe, and a correction value for obtaining a phase change amount of the measuring end device based on the phase shift obtained in the phase shift acquisition step. Acquirer A method for measuring a correction value, which comprises: 2. The correction value measuring method according to claim 1, wherein in the correction value acquiring step, the phase change amount is obtained from the following expression 1. ## EQU1 ## δ = (1 / m)  (b / a) where δ is the phase change amount, m is a constant based on the complex refractive index of the measuring end protractor, and b / a is Phase shift obtained in the phase shift acquisition step 3. The correction value measuring method according to claim 1, wherein at least the ringing side end face is smooth so that the reference end device does not cause a phase change when light is reflected on the ringing side end face. A method for measuring a correction value, characterized in that 4. The correction value measuring method according to claim 1, wherein the reference end device has a complex refractive index that does not cause a phase change when light is reflected on the ringing end face. And how to measure the correction value. 5. The correction value measuring method according to claim 1, wherein the base plate and the reference end gauge are made of synthetic quartz or borosilicate glass. A method for measuring a correction value, which is characterized in that 6. The correction value measuring method according to claim 1, wherein the non-ringing surface of the base plate is predetermined in a direction orthogonal to an optical axis of the second split light from the half mirror. A method for measuring a correction value, which is characterized by being inclined at an angle. 7. The correction value measuring method according to claim 6, wherein an angle of inclination of the non-ringing surface of the base plate is such that reflected light on the non-ringing surface does not return to the half mirror and transmitted light of the base plate. Is an angle of incidence from a direction substantially orthogonal to the ringing side end face of the reference end device and the ringing side end face of the measurement end device.