WO2018012898A1

WO2018012898A1 - Apparatus for altering length of optical path for three-dimensional surface measurement

Info

Publication number: WO2018012898A1
Application number: PCT/KR2017/007512
Authority: WO
Inventors: 장민호; 이수복; 정문철; 정영석
Original assignee: 주식회사 메디트
Priority date: 2016-07-13
Filing date: 2017-07-13
Publication date: 2018-01-18
Also published as: KR20180007539A

Abstract

The present invention relates to an apparatus for altering an optical path for three-dimensional surface measurement; comprises a ring-shaped path alteration reflection part or a ring-shaped refraction part for altering a light path using a rotational body rotated by a motor; and thus can easily obtain consecutive data due to rotation of the rotational body, improves the accuracy of light being collected, and can accurately adjust the distance or the refractive index of reflected light by adjusting the distance or the refractive index of reflected light using only rotational motion so that the distance and the refractive index of light are consistently altered by rotational motion having a constant speed, and can be used as long as the degree of parallelism between a reference beam and a rotational axis is correct, thereby improving the convenience when setting an alignment.

Description

Optical path length change device for 3D surface measurement

The present invention relates to an optical path length changing device for three-dimensional surface measurement. More specifically, the optical path length changing device for three-dimensional surface measurement can be easily obtained by changing a light path to a rotating body. It is about.

In general, a three-dimensional surface measuring apparatus measuring a three-dimensional shape of a measurement object may obtain a three-dimensional shape of an object by generating and analyzing an interferometer pattern on the surface of the measurement object using an interferometric method.

Figure 1 shows a three-dimensional surface measuring apparatus using an interferometric method.

Referring to FIG. 1, a three-dimensional surface measuring apparatus using an interferometric method reflects light divided by a light source 1 for emitting light, a light splitter 2 for splitting the emitted light source, and a light splitter 2. A path changing reflector 3 and a detector 4 which are moved by the furnace changing device.

That is, the light splitter 2 divides the light emitted from the light source 1 to be irradiated to the measuring object 5 and the path changing reflector 3, and the light and the path changing reflection irradiated to the measuring object 5 are reflected. The light irradiated to the unit 3 is reflected by the measurement object 5 and the path changing reflector 3 and received by the detector 4 through the light splitter 2.

The path changing reflector 3 is moved by the optical path changing apparatus so that the distance between the path changing reflector 3 and the light splitter 2 is adjusted to detect the depth position with respect to the surface of the measuring object 5.

The optical path changing device for moving the path changing reflector 3 to adjust the distance between the optical splitter 2 and the path by the ball screw 6b rotated by the motor 6a as shown in FIG. 2. The LM guide 6 which linearly reciprocates the change reflection part 6c is used.

The LM guide 6 of the ball screw 6b structure changes the rotation direction of the motor 6a quickly and repeatedly by changing the position of the path change reflector 6c while continuously changing the rotation direction of the motor 6a. Since the life of the motor 6a is short because it is used, there is a problem that the motor must be replaced frequently.

In addition, the LM guide 6 of the ball screw 6b structure is operated again after the motor 6a is stopped and acceleration is generated, and deceleration occurs while the motor 6a is stopped. Accurate position detection is not easy and there is a problem in that the parallelism of the ball screw and the position adjustment of the reflector are very important for alignment of the light beams while the path changing reflector 6c is moving.

3 is a view showing another example of a conventional optical path changing device. Referring to FIG. 3, the optical path changing device may use a cam-type mechanism even when the motor 7a rotates in one direction. 7c) may use the LM guide 7 of the cam structure 7c which linearly reciprocates.

However, the LM guide 7 of the cam structure 7b has a problem that a lot of vibration occurs during operation, and the linear reciprocating motion on the cam structure 7b has a deceleration period, so that the position of the path change reflecting portion 7c is present. The exact location of the problem was not easy.

SUMMARY OF THE INVENTION An object of the present invention is to provide a light path length changing device for measuring a three-dimensional surface that can easily secure continuous data by changing a light path into a rotating body and accurately adjust the distance of light.

In order to achieve the above object, the three-dimensional surface measurement optical path length changing device according to the present invention, the three-dimensional surface measurement optical path for measuring the surface depth of the measurement object by changing the path length of the light emitted from the light source As the length change device, it characterized in that it comprises a rotation motor, a path length change rotating body which is rotated by the rotation motor to change the path length of the light.

In the present invention, the path length changing rotating body is a reflecting rotating body including a path changing reflector reflecting light in a path through which the light passes, and the path changing reflecting part has a distance different from the light splitter in the circumferential direction. It can be formed to be.

In the present invention, the reflective rotating body may be rotated about a rotation axis disposed in parallel with a reference beam reflected through the reflective surface of the path changing reflector.

In the present invention, the reflective surface of the rerouting reflector may be formed in a step shape.

In the present invention, the path changing reflector is formed to have a plurality of layers gradually increasing in a 360-degree radius with respect to the reference line passing through the rotation center of the reflecting rotating body, the surface of each layer is provided with a reflective surface stepped It can have a distance farthest from the light splitter in the first layer at the baseline, and the distance closest to the light splitter in the last layer at a 360 degree radius from the baseline.

In the present invention, the reflective surface of the path changing reflector may be formed as an inclined surface.

In the present invention, the path change reflector is formed of an inclined surface gradually increasing in a 360 degree radius with respect to the reference line passing through the center of rotation of the reflecting rotating body to have a distance farthest from the light splitter at the reference line, and 360 degrees from the reference line. It may have the closest distance to the light splitter by having the highest height at a portion that meets the reference line in the radius.

In the present invention, the path length change rotating body includes a refraction rotating body having a refraction unit positioned in a path through which light passes and refracting light, and the refraction unit is formed to have a shape having a different thickness in the circumferential direction. An optical path length change effect may be generated due to a difference in transmission speed of light transmitted to the light receiver.

In the present invention, the axis of rotation of the refractive rotating body may be arranged in parallel with the light emitted through the light source.

In the present invention, the refraction portion may be formed in a step shape in which the thickness gradually increases.

In the present invention, the refracting portion has a stepped shape having a plurality of layers gradually increasing in a 360 degree radius with respect to the reference line passing through the rotation center of the refraction rotating body has the shortest distance transmitted from the first layer in the reference line is irradiated with light It has the shortest distance between the portion and the light-receiving portion, and the longest distance transmitted in the last layer of the 360-degree radius from the reference line can have the longest distance between the portion to which light is irradiated and the light-receiving portion.

In the present invention, the refractive portion may be formed as an inclined surface.

In the present invention, the refracting portion is formed to have an inclined surface gradually increasing in a 360-degree radius with respect to the reference line passing through the rotation center of the refraction rotating body so that light is irradiated from the thinnest reference line by gradually increasing the transmitted length. To have the shortest distance between the portion and the light-receiving portion, and to have the highest height at the portion that meets the baseline at a 360 degree radius from the baseline to have the longest distance between the portion to which light is irradiated and the light-receiving portion. Can be.

The present invention changes the path of the light to the rotating body is formed so that the rotating body has an inclined surface has an effect that can easily secure a continuous data.

The present invention changes the path of the light to the rotating body and has the effect of improving the accuracy of the collected light is formed by the step of reflecting or refracting the planar surface.

The present invention is to adjust the distance of the light or the refractive index of the light reflected only by the rotational movement to change the distance and the refractive index of the light constantly when the rotational movement is constant speed has the effect of accurately adjusting the distance or the refractive index of the light .

In addition, the present invention can be used if only the parallelism between the reference beam (rotation) and the axis of rotation can be used, there is an effect of improving the convenience when setting the alignment.

1 is a schematic view showing a three-dimensional surface measuring apparatus using a general interferometric method.

Figure 2 is a perspective view showing an example of a conventional optical path length change device for three-dimensional surface measurement.

3 is a perspective view showing another example of a conventional optical path length changing device for three-dimensional surface measurement.

Figure 4 is a perspective view showing an embodiment of the reflective type in the optical path length change device for measuring three-dimensional surface in accordance with the present invention.

Figure 5 is a perspective view showing another embodiment of the reflection type in the optical path length change device for measuring three-dimensional surface according to the present invention.

Figure 6 is a perspective view showing an embodiment of the transmission type in the optical path length change device for measuring three-dimensional surface according to the present invention.

Figure 7 is a perspective view showing another embodiment of the transmission type in the optical path length change device for measuring three-dimensional surface according to the present invention.

* Description of the major symbols in the drawings *

1: light source 2: light splitter

3: path changing reflector 4: detector

5: measuring object 10: rotating motor

11: rotational force transmission unit 20: a reflection rotor

30 cable clamping portion 40 refraction rotating body

41: refracting portion 51: the portion to which light is irradiated

52: light receiver 100: base member

110: support

When described in detail with reference to the accompanying drawings a preferred embodiment of the present invention. Prior to the detailed description of the invention, the terms or words used in the specification and claims described below should not be construed as limiting in their usual or dictionary meanings. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only one of the most preferred embodiments of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

The present invention is a three-dimensional surface measurement optical path length changing device for measuring the surface depth of the measurement object by changing the path length of the light emitted from the light source, rotated by the rotary motor 10 to change the path length of the light Path length change includes a rotating body.

The path length changing rotating body is a reflecting rotating body 20 having a path changing reflecting part 3 reflecting light in a path through which light passes, and the path changing reflecting part 3 has a reflecting surface in a circumferential direction. It may be formed to have a different distance from the divider 2, an embodiment thereof will be described in detail below with reference to FIGS.

The optical path length changing device for measuring a three-dimensional surface according to the present invention includes a light source 1 emitting light, a light splitter 2 for dividing light emitted from the light source, and a light split from the light splitter 2 The path changing reflector 3, the light reflected by the measuring object 5 and the light reflected by the path changing reflector 3, are included in the three-dimensional surface measurement of the path changing reflector 3. It is an optical path length changing device for measuring a three-dimensional surface for adjusting the distance between the reflecting surface and the light splitter (2).

Referring to FIG. 1, the light emitted from the light source is split in the light splitter 2 and irradiated to the measurement object 5 and the path changing reflector 3, respectively.

The light irradiated onto the measurement object 5 is reflected by the measurement object 5 and passes through the light splitter 2, and then received by the detector 4. In addition, the light irradiated to the path change reflector 3 is reflected by the path change reflector 3 to be directed to the detector 4 through the light splitter 2 and received by the detector 4.

That is, if the light divided by the light splitter 2 is reflected by the measuring object 5 and the path changing reflector 3, respectively, and the total moving distance of the light at the moment of being received by the detector 4 is the same, Interfere with the detector 4

When the distance between the reflecting surface of the rerouting reflector 3 and the detector 4 is changed, that is, the depth position of the surface of the measurement object 5 according to the position at which the reflecting surface of the rerouting reflector 3 moves. Can be detected.

Light reflected by the path changing reflector 3 and received by the detector 4 is referred to as a reference beam, and light that is reflected after being irradiated to the measurement object and received by the detector 4 is a sample beam. It can be called (Sample Beam).

Detecting the depth position of the surface of the measuring object 5 by changing the distance between the reflecting surface of the path changing reflector 3 and the detector 4 is a known technique in a three-dimensional surface measuring apparatus using an interferometric method. Note that further description is omitted.

Figure 4 is a perspective view showing an embodiment of the reflective type in the three-dimensional surface measurement optical path length changing apparatus according to the present invention, Figure 5 is a reflective type in the three-dimensional surface measurement optical path length changing apparatus according to the present invention 4 and 5 are views showing respective embodiments of the reflective optical path length changing device used in the three-dimensional surface measuring apparatus using an interferometric method.

4 and 5, the optical path length changing device for measuring a three-dimensional surface according to the present invention is rotated by a rotating motor 10 and the rotating motor 10 and changes the path on a surface facing the optical splitter. It includes a reflection rotating body 20 is provided with a reflecting portion (3).

The optical path length changing device for measuring a three-dimensional surface according to the present invention may further include a cable clamping unit 30 which may connect an optical cable to the front side of the optical splitter.

The reflection rotating body 20 is rotated by receiving the rotational force of the rotary motor 10, the optical path length change device for measuring the three-dimensional surface according to the present invention for the reflection of the rotational force of the rotary motor 10 It may further include a rotational force transmission unit 11 for transmitting to the rotating body (20).

The rotational force transmitting unit 11 is an example of transmitting the rotational force of the rotary motor 10 to the reflective rotating body 20 in a belt structure.

For example, the axis of rotation of the reflective rotating body 20 is disposed in parallel with the reference beam reflected through the reflective surface of the path changing reflector 3.

The rotating shaft of the reflective rotating body 20 is rotatably coupled to the support 110, the support 110 is an example that is vertically fixed to the upper surface of the base member 100 is fixed.

The path changing reflector 3 is formed in a ring shape on the front surface of the reflecting rotating body 20, that is, the surface facing the light splitter, and is positioned so that the light divided by the light splitter may hit.

The reflecting surface of the rerouting reflector 3 is formed to have a different distance from the light splitter in the circumferential direction.

4 is a view illustrating that the reflective surface of the path changing reflector 3 is formed in a step shape.

That is, referring to FIG. 4, the path change reflector 3 is formed to have a plurality of layers gradually increasing in a 360 degree radius with respect to the reference line passing through the center of rotation of the reflective rotor 20. As an example, the reflective surface is provided on the surface of the layer to have a step shape.

The path changing reflector 3 has a stepped shape having a plurality of layers gradually increasing in a 360 degree radius with respect to the reference line passing through the center of rotation of the reflecting rotating body 20. And the closest distance to the light splitter in the last layer at a 360 degree radius from the baseline.

The reflection rotating body 20 is rotated around a rotation axis disposed in parallel with a reference beam reflected through the reflection surface of the path changing reflection part 3, and the light divided by the light splitter has the lowest height. From the reflective surface of the first layer to hit the reflective surface of the last layer of the highest height sequentially and reflected, the last layer having the highest height from the reflective surface of the first layer having the lowest height by the rotation of the reflective rotor 20 The reflection hits sequentially until the reflective surface of the is repeated repeatedly.

The path changing reflection part 3 is formed in a step shape that increases in height in order to ensure the sequential data continuously by the reflective surface of the plane and to improve the accuracy of the collected light.

5 is a view illustrating that the reflecting surface of the path changing reflector 3 is inclined.

That is, referring to FIG. 5, the path change reflector 3 is formed to have an inclined surface which gradually increases in a radius of 360 degrees with respect to a reference line passing through the rotation center of the reflective rotating body 20, and on the inclined surface. As an example, a reflective surface is provided and the reflective surface has an inclined inclined surface.

The path changing reflector 3 is formed of an inclined surface that gradually increases in a 360 degree radius with respect to the reference line passing through the center of rotation of the reflective rotating body 20 to have the longest distance from the light splitter at the reference line. It has the highest height at the part where it meets the reference line at a 360 degree radius from the reference line to have the closest distance to the light splitter.

The reflective rotating body 20 is rotated about a rotation axis arranged in parallel with a reference beam reflected through the reflecting surface of the path changing reflecting part 3, and by the rotation of the reflective rotating body 20 The light split by the light splitter is repeatedly reflected by hitting a reflective surface having an inclination gradually increasing in height at the lowest reference line.

The path changing reflector 3 is formed of an inclined surface in which the reflecting surfaces are sequentially increased in height so that the continuous data can be more surely secured.

In the present invention, the path length change rotating body includes a refracting rotating body 40 having a refracting part 41 positioned in a path through which light passes and refracting light, and the refracting part 41 has a circumference. It is formed to have a shape having a different thickness in the direction can cause the effect of changing the length of the optical path due to the difference in the transmission speed of the light transmitted to the light-receiving unit 52, an embodiment thereof with reference to Figures 6 and 7 It demonstrates in detail below.

6 and 7 are perspective views showing an embodiment applied to the transmissive three-dimensional surface measuring apparatus in the optical path length change device for the three-dimensional surface measuring apparatus according to the present invention, the transmissive three-dimensional surface measuring apparatus is emitted from the light source The measurable depth is changed by refraction of the light to be transmitted to the light receiving unit 52 to generate an optical path difference between the portion 51 and the light receiving unit 52 to which light is irradiated, and the reflection of FIGS. 4 and 5 is substantially reduced. Type, that is, the same as the interferometric method using a light splitter, which is the same as the principle of a known transmissive three-dimensional surface measuring apparatus, and thus a detailed description thereof will be omitted.

Another embodiment of the optical path length changing device for a three-dimensional surface measuring apparatus according to the present invention is rotated by the rotary motor 10, the rotary motor 10 and to be transmitted by refracting the light of the light source on the surface facing the light source It includes a refracting rotating body 40 is provided with a refracting portion (41).

The front portion 51 of the refractive rotating body 40 is a portion 51 is irradiated with light. In addition, the optical path length changing device for measuring a three-dimensional surface according to the present invention may further include a cable clamping unit 30 that is provided on the front side of the portion 51 is irradiated with light and can connect the optical cable.

The refractive rotating body 40 is rotated by receiving the rotational force of the rotary motor 10, the optical path length change device for measuring a three-dimensional surface according to the present invention is the refractive force of the rotational motor 10 for the refractive It may further include a rotation force transmission unit 11 for transmitting to the rotating body 40.

The rotational force transmitting unit 11 is an example of transmitting the rotational force of the rotary motor 10 to the refractive rotating body 40 in a belt structure.

For example, the axis of rotation of the refractive rotating body 40 is disposed in parallel with the light emitted through the light source.

The rotating shaft of the refractive rotating body 40 is rotatably coupled to the support 110, the support 110 is an example that is fixed to the upper surface of the base member 100 is vertically fixed.

The refraction portion 41 is formed in a ring shape on the front surface of the refraction rotating body 40, that is, a surface facing the light source, and is positioned to transmit light emitted from the light source.

The refracting portion 41 is formed to have a different thickness in the circumferential direction to generate a difference in the distance transmitted, thereby generating a light path difference between the portion 51 to which light is irradiated and the light receiving portion 52. The refraction portion 31 is formed to have the same refractive index and have a different thickness in the circumferential direction to generate a difference in the distance transmitted, thereby reducing the optical path difference between the portion 51 to which light is irradiated and the light receiving portion 52. It is taken as an example.

6 is a view showing that the refraction portion 41 is formed in a step shape and has different refraction distances in each layer.

That is, referring to FIG. 6, the refraction portion 41 is formed to have a plurality of layers gradually increasing in a 360 degree radius with respect to the reference line passing through the center of rotation of the refractive rotor 40, and in each layer For example, it has a stepped shape in which a planar transmissive part is formed.

The refracting portion 41 has a step shape having a plurality of layers gradually increasing in a 360 degree radius with respect to the reference line passing through the center of rotation of the refractive rotor 40, so that the distance transmitted from the first layer at the reference line is the most. The part 51 and the light-receiving part which have a shortest distance between the light-receiving part 51 and the light-receiving part 52 and the longest distance transmitted in the last layer of a 360 degree radius from the reference line are shortest. As an example, the distance refracted to have the longest distance between the two 52 is gradually increased in the circumferential direction.

The refractive rotating body 40 is rotated about a rotation axis arranged in parallel with the light emitted from the light source, and the height of the light passing through the portion 51 to which the light is irradiated is the highest in the first layer having the lowest height. Refracted and transmitted sequentially up to the last high layer, the transmission distance of each layer is gradually increased from the first layer to the last layer having the highest height so that the distance between the light-receiving portion 52 and the light-receiving portion 52 is gradually increased. do. In addition, the rotation of the refraction rotating body 40 is repeated to be transmitted and refracted sequentially from the first layer having the lowest height to the last layer having the highest height.

The refracting portion 41 has a flat refracting surface and is formed in a step shape in which the height is sequentially increased to improve the accuracy of light collected by the flat refracting surface.

7 is a view illustrating that the refraction portion 41 is formed as an inclined surface.

That is, referring to FIG. 7, the refraction portion 41 is formed to have an inclined surface whose height gradually increases with a radius of 360 degrees with respect to the reference line passing through the center of rotation of the refraction rotating body 40 so as to gradually increase in thickness. For example, having a.

That is, the refraction portion 41 is formed as an inclined surface whose height gradually increases with a radius of 360 degrees with respect to the reference line passing through the center of rotation of the refraction rotating body 40, thereby gradually increasing the length of light transmission so that the light is reflected from the reference line. The portion 51 and the light-receiving portion 52 and the light-receiving portion 52 to which the light is irradiated to have the highest distance between the irradiated portion 51 and the light-receiving portion 52 closest to each other and meet the baseline at a 360 degree radius from the baseline Make the distance between them the most.

The refracting portion 41 is rotated around a side of the axis of rotation that is emitted from the light source, the light has a slope in which the height gradually increases from the reference line of the lowest height by the rotation of the refractive body 40 What is refracted and transmitted through the refraction portion 41 continues to be repeated.

The refracting portion 41 is formed with an inclined surface that is sequentially increased in height so as to easily secure data continuously.

The present invention changes the path of the light to the rotating body and is formed so that the rotating body has an inclined surface can easily secure continuous data.

The present invention changes the path of the light to the rotating body and the planar reflecting surface or refracting surface is formed in a step shape to improve the accuracy of the collected light.

The present invention is to adjust the distance of the light or the refractive index of the light reflected only by the rotational movement to constantly change the distance and the refractive index of the light when the rotational movement is a constant speed can accurately adjust the distance or the refractive index of the light.

In addition, the present invention can be used if only the parallelism between the reference beam (rotational axis) and the rotation axis is matched to improve the convenience when setting the alignment.

As described above, the best embodiment has been disclosed in the drawings and the specification. The present invention is not limited to the above embodiments and various changes and modifications may be made by those skilled in the art to which the present invention pertains without departing from the spirit of the present invention, and the true technical protection of the present invention. The scope should be defined by the spirit of the appended claims.

According to the present invention, it is possible to manufacture a three-dimensional surface measuring optical path length changing device that can easily secure the continuous data by changing the path of the light to the rotating body.

Claims

It is a 3D surface path length changing device for measuring the surface depth of the measurement object by changing the path length of the light emitted from the light source,

Rotary motor;

3. The optical path length changing device of claim 3, further comprising a path length changing rotating body rotating by the rotary motor and changing a path length of light.
The method according to claim 1,

The path length changing rotating body is a reflecting rotating body provided with a path changing reflector reflecting light in a path through which light passes,

And the path changing reflector is formed such that the reflecting surface has a different distance from the light splitter in the circumferential direction.
The method according to claim 2,

And the reflection rotating body is rotated about a rotation axis disposed in parallel with a reference beam reflected through the reflecting surface of the path changing reflector.
The method according to claim 2,

3. The optical path length changing device of claim 3, wherein the reflecting surface of the path changing reflector is formed in a step shape.
The method according to claim 2,

The path changing reflector is formed to have a plurality of layers gradually increasing in a 360 degree radius with respect to the reference line passing through the center of rotation of the reflecting rotating body, the surface of each layer is provided with a reflective surface has a stepped shape,

And a distance farthest from the light splitter in the first layer at the baseline, and a distance closest to the light splitter in the last layer at a 360 degree radius from the baseline.
The method according to claim 2,

3. The optical path length changing device of claim 3, wherein the reflecting surface of the path changing reflector is formed as an inclined surface.
The method according to claim 2,

The path changing reflector is formed as an inclined surface which gradually increases in height by 360 degrees with respect to the reference line passing through the rotation center of the reflecting rotating body to have a distance farthest from the light splitter at the reference line, and at a 360 degree radius from the reference line. 3. The optical path length changing device of claim 3, wherein the optical path length measuring device has a height that is closest to the light splitter so as to have the highest height at a portion meeting the reference line.
The method according to claim 1,

The path length change rotating body includes a refracting rotating body having a refraction unit positioned in a path through which light passes and refracting and transmitting light.

And the refractive portion is formed to have a shape having a different thickness in the circumferential direction to generate an optical path length changing effect due to a difference in transmission speed of light transmitted to the light receiving portion.
The method according to claim 8,

3. The optical path length changing device of claim 3, wherein the rotation axis of the refractive rotating body is disposed in parallel with the light emitted through the light source.
The method according to claim 8,

The refraction portion is a three-dimensional surface measurement optical path length change device, characterized in that the thickness of each layer is formed in a step shape gradually thickened.
The method according to claim 8,

The refracting portion has a step shape having a plurality of layers gradually increasing in a 360 degree radius with respect to the reference line passing through the rotation center of the refraction rotating body, so that the distance transmitted from the first layer at the baseline is the shortest and is irradiated with light. 3D surface measurement, characterized in that it has the shortest distance between the light-receiving portion, and has the longest distance between the light-receiving portion and the portion to which light is radiated because the distance transmitted in the last layer of 360 degree radius from the reference line is the longest. Light path length change device.
The method according to claim 8,

The optical path length changing device for measuring a three-dimensional surface, wherein the refractive portion is formed as an inclined surface.
The method according to claim 8,

The refracting portion is formed to have an inclined surface whose height gradually increases with a radius of 360 degrees with respect to the reference line passing through the rotation center of the refraction rotating body, and gradually increases the transmitted length, thereby allowing the light to be irradiated from the thinnest reference line and the The distance between the light receiving unit has the closest distance, and has the highest height at the portion that meets the reference line at a 360 degree radius from the reference line to have the longest distance between the portion to which light is irradiated and the light receiving unit 3D surface path length changing device for measuring.