KR20200040680A - Optical interferometer - Google Patents

Abstract

Disclosed is an optical interference system capable of improving measuring precision. According to the present invention, the optical interference system may comprise: a light source generating light; a main interferometer making a measurement light reflected from a sample by an object lens and a reference light reflected from a reference mirror among the lights generated by the light source to interfere, thereby generating a main interference signal; an auxiliary interferometer making measurement lights for vibration and noise, which are reflected from an auxiliary mirror adjacent to the sample and an auxiliary mirror adjacent to the reference mirror, respectively to measure a vibration signal and/or an undesired noise signal among the light headed towards the reference mirror and the light generated by the light source and headed towards the sample, to interfere, thereby generating an auxiliary interference signal; a detection unit detecting the main interference signal and the auxiliary interference signal; and a control unit, when the optical axis-directional positions of the main interference signal and the auxiliary interference signal determined from an optical spectrum analysis on the main interference signal and the auxiliary interference signal are the optical axis-directional position including the vibration signal and/or the undesired noise signal, changing the optical axis-directional position of the main interference signal to the original optical axis-directional position as much as the amount of change of the optical axis-directional position of the auxiliary interference signal.

Description

Optical Interference System {OPTICAL INTERFEROMETER}

The disclosed invention relates to an optical interference system, and more particularly, to an optical interference system capable of increasing measurement precision.

In general, a measurement device using an optical interferometer is widely used in a field requiring high-precision 3D measurement.

The measuring device using an optical interferometer can be divided into three parts: a light source, an optical system, and a measuring device.

The optical system is composed of optical elements such as a lens for measuring and instruments such as various holders and transport devices, and the measuring device includes a beam splitter for inducing light interference, a reference mirror, and a sensing unit for detecting interfered light. It is composed of utensils.

In particular, the optical system is designed appropriately for the object to be measured to measure in the form of an optical probe. In industrial applications, it is mainly combined with other equipment and physically separated from the rest of the light source and measuring unit.

For this reason, the optical probe, in addition to noise signals such as vibration signals and signal instability caused by the optical probe structure itself, is combined with other equipment to prevent unwanted vibrations caused by vibration signals and / or temperature and humidity changes occurring in the optical probe structure. Measure the noise signal.

The measurement device using the existing optical interferometer has poor measurement accuracy because the sample signal contains vibration signals generated in the optical probe structure and / or unwanted noise signals generated due to temperature and humidity changes.

For the above reasons, one aspect of the disclosed invention is to provide an optical interference system capable of increasing measurement accuracy by detecting and compensating for vibration signals and / or unwanted noise signals generated in an optical probe structure.

An optical interference system according to an aspect of the disclosed invention includes a light source that generates light; A main interferometer for generating a main interference signal by interfering with the reference light reflected from the reference mirror and the measurement light reflected by the sample among the light generated from the light source; Vibration noise reflected from the auxiliary mirror adjacent to the sample and the auxiliary mirror adjacent to the reference mirror to measure vibration signals and / or unwanted noise signals among light emitted from the light source and directed to the sample and light directed to the reference mirror An auxiliary interferometer that generates an auxiliary interference signal by interfering with the measurement light; A sensing unit detecting the main interference signal and the auxiliary interference signal; And the optical axis direction positions of the main interference signal and the auxiliary interference signal determined from optical spectrum analysis of the main interference signal and the auxiliary interference signal are optical axis directions including vibration signals and / or unwanted noise signals. It may include a control unit for changing the optical axis position of the main interference signal to the original optical axis position by the amount of change in the optical axis direction position of the auxiliary interference signal.

The auxiliary mirror adjacent to the sample is provided so that the two face each other to reflect the measurement light for vibration noise; Two auxiliary mirrors adjacent to the reference mirror may be provided to face each other or may be provided as one to reflect measurement light for vibration noise.

The control unit may calculate the main interference signal and the auxiliary interference signal in terms of distance through Fourier transform using the following equation.

<Mathematics>

,

,

는 푸리에 변환을 통한 거리에 관한 메인 간섭신호,

는 간섭에 의한 envelope function,

은 굴절률,

은 광이 광원부터 시작해서 샘플과 기준미러에 반사되어 돌아오는 경로에 대한 거리,

는 푸리에 변환을 통한 거리에 관한 보조 간섭신호,

는 광이 광원부터 시작해서 샘플에 인접한 보조미러와 기준미러에 인접한 보조미러에 반사되어 돌아오는 경로에 대한 거리이다.here,

Is the main interference signal about the distance through Fourier transform,

Is the envelope function due to interference,

Silver refractive index,

The distance to the path where silver light returns from the light source to the sample and the reference mirror,

Is a secondary interference signal on the distance through Fourier transform,

Is the distance to the path from which the light returns from reflecting back to the auxiliary mirror adjacent to the sample and the reference mirror starting from the light source.

The control unit may calculate the main interference signal and the auxiliary interference signal including the vibration signal and / or the unwanted noise signal in terms of distance through Fourier transform using the following equation.

<Mathematics>

,

,

는 푸리에 변환을 통한 거리에 관한 메인 간섭신호,

는 간섭에 의한 envelope function,

은 굴절률,

은 광이 광원부터 시작해서 샘플과 기준미러에 반사되어 돌아오는 경로에 대한 거리,

는 푸리에 변환을 통한 거리에 관한 보조 간섭신호,

는 광이 광원부터 시작해서 샘플에 인접한 보조미러와 기준미러에 인접한 보조미러에 반사되어 돌아오는 경로에 대한 거리,

는 진동신호 및/또는 원하지 않는 잡음신호에 대한 거리이다.here,

Is the main interference signal about the distance through Fourier transform,

Is the envelope function due to interference,

Silver refractive index,

The distance to the path where silver light returns from the light source to the sample and the reference mirror,

Is a secondary interference signal on the distance through Fourier transform,

Is the distance to the path from which the light starts from the light source and reflects back to the secondary mirror adjacent to the sample and the secondary mirror adjacent to the reference mirror.

Is the distance to the vibration signal and / or the unwanted noise signal.

The control unit may calculate a position change amount in the optical axis direction of the auxiliary interference signal using the following equation.

<Mathematics>

는 보조 간섭신호의 광축방향 위치 변화량,

는 간섭에 의한 envelope function,

은 굴절률,

는 광이 광원부터 시작해서 샘플에 인접한 보조미러와 기준미러에 인접한 보조미러에 반사되어 돌아오는 경로에 대한 거리,

는 진동신호 및/또는 원하지 않는 잡음신호에 대한 거리이다.here,

Is the amount of change in the optical axis position of the auxiliary interference signal,

Is the envelope function due to interference,

Silver refractive index,

Is the distance to the path from which the light starts from the light source and reflects back to the secondary mirror adjacent to the sample and the secondary mirror adjacent to the reference mirror.

Is the distance to the vibration signal and / or the unwanted noise signal.

According to one aspect of the disclosed invention, it is possible to provide an optical interference system capable of increasing measurement accuracy by detecting and compensating for vibration signals and / or unwanted noise signals generated in an optical probe structure.

1 shows a configuration of an optical interference system according to an embodiment.
2 shows another configuration of an optical interference system according to an embodiment.
3 shows an optical axis profile in an optical interference system according to an embodiment.
4 is a diagram illustrating an optical axis profile including a vibration signal and / or an unwanted noise signal in an optical interference system according to an embodiment.
5 shows an optical axis profile for changing the optical axis position of the main interference signal in the optical interference system according to an embodiment.

The same reference numerals refer to the same components throughout the specification. This specification does not describe all elements of the embodiments, and the general contents in the art to which the disclosed invention belongs or overlapping contents between the embodiments are omitted. The term 'unit, module, member, block' used in the specification may be implemented by software or hardware, and according to embodiments, a plurality of 'unit, module, member, block' may be implemented as one component, It is also possible that one 'part, module, member, block' includes a plurality of components.

Throughout the specification, when a part is "connected" to another part, this includes not only a direct connection but also an indirect connection, and an indirect connection includes connecting through a wireless communication network. do.

Also, when a part “includes” a certain component, this means that other components may be further included rather than excluding other components, unless otherwise specified.

Throughout the specification, when one member is positioned "on" another member, this includes not only the case where one member is in contact with the other member but also another member between the two members.

Terms such as first and second are used to distinguish one component from other components, and the component is not limited by the above-mentioned terms.

Singular expressions include plural expressions, unless the context clearly has an exception.

Hereinafter, working principles and embodiments of the disclosed invention will be described with reference to the accompanying drawings.

1 shows a configuration of an optical interference system according to an embodiment.

Since the speed of the measurement light for measuring a sample is very fast, the optical interference system interferes with the measurement light reflected by the sample and the reference light reflected by the reference mirror to measure the sample's measurement accuracy using a composite interference signal composed of the measurement light and the reference light. It is built to raise.

In addition to noise signals such as vibration signals and signal instability caused by bolt and nut fastening in the optical probe structure itself, the optical interference system generates vibration signals and / or temperature changes in the optical probe structure when the sample is transferred by the conveyor belt. And the noise signal generated by changes in humidity, etc. is included, so measurement accuracy is poor.

Hereinafter, an optical interference system capable of increasing measurement accuracy even when a vibration signal and / or an unwanted noise signal generated in the optical probe structure is generated will be described.

Referring to FIG. 1, the optical interference system may include a light source 110, main interferometers 120 and 130, auxiliary interferometers 140 and 150, a sensing unit 160, and a control unit 170. .

The light source 110 generates light. For example, the light source 110 may include a light emitting diode (LED), a super luminescent diode (SLD), and a laser. Without being limited to this, the light source 110 may be composed of various elements capable of generating light.

The main interferometers 120 and 130 may include a first main interferometer 120 and a second main interferometer 130. The first main interferometer 120 may include a first beam splitter 121, a second beam splitter 122, and an objective lens 123. The second main interferometer 130 may include a third beam splitter 131, a fourth beam splitter 132, and a reference mirror 133.

The main interferometers 120 and 130 generate a main interference signal by interfering with the measurement light reflected by the first main interferometer 120 and the reference light reflected by the second main interferometer 130 to measure the sample S Order.

Specifically, the first beam splitter 121 injects some of the light output from the light source 110 into the second beam splitter 122 and the remaining light into the third beam splitter 131.

The second beam splitter 122 causes some of the light output from the first beam splitter 121 to enter the objective lens 123.

The objective lens 123 transmits light output from the second beam splitter 122. The objective lens 123 has a magnification determined according to its size. For example, as the length of the objective lens 123 increases, the magnification increases. The sample S is positioned on the focal point of the objective lens 123. This process represents the light path of arrow ①.

The light passing through the objective lens 123 is incident on the sample S and then reflected on the sample S. The measurement light reflected by the sample S enters the second beam splitter 122 through the objective lens 123, and the second beam splitter 122 enters the measurement light into the first beam splitter 121. The first beam splitter 121 transmits the measurement light to the detector 160. This process represents the light path of arrow ②.

The third beam splitter 131 injects the remaining light among the light output from the first beam splitter 121 to the fourth beam splitter 132, and the fourth beam splitter 132 outputs from the third beam splitter 131 The reflected light is reflected on the reference mirror 133. This process represents the light path of arrow ①.

The fourth beam splitter 132 injects the reflected reference light into the third beam splitter 131. The third beam splitter 131 injects the reference light output from the fourth beam splitter 132 into the first beam splitter 121. The first beam splitter 121 transmits the reference light to the detector 160. This process represents the light path of arrow ③.

The auxiliary interferometers 140 and 150 may include a first auxiliary interferometer 140 and a second auxiliary interferometer 150. The first auxiliary interferometer 140 may include a first auxiliary mirror 141 and a second auxiliary mirror 142. The second auxiliary interferometer 150 may include a third auxiliary mirror 151 and a fourth auxiliary mirror 152.

The auxiliary interferometers 140 and 150 measure the vibration light and / or the measurement light for the first vibration noise reflected by the first auxiliary interferometer 140 in order to measure the unwanted noise signal generated according to temperature change and humidity change. 2 Interference of the measurement light for the second vibration noise reflected by the auxiliary interferometer 150 generates an auxiliary interference signal.

Specifically, the second beam splitter 122 reflects the remaining light among the light output from the first beam splitter 121 to the first auxiliary mirror 141 adjacent to the sample S. The first auxiliary mirror 141 injects the measurement light for the first vibration noise reflected on the neighboring second auxiliary mirror 142 into the second beam splitter 122. The first beam splitter 121 transmits the measurement light for the first vibration noise output from the second beam splitter 122 to the detector 160. This process represents the light path of arrow ④.

The first auxiliary mirror 141 and the second auxiliary mirror 142 may be provided to be fixed to face each other. The first auxiliary mirror 141 and the second auxiliary mirror 142 are fixedly provided to face each other in the optical probe structure A, and the second beam splitter 122 and the objective lens 123 in the optical probe structure A ) Can be provided together. The first auxiliary mirror 141 may be fixed at a constant angle to reflect the measurement light for the first vibration noise with respect to the second auxiliary mirror 142 and the second beam splitter 122.

The first auxiliary mirror 141 and the second auxiliary mirror 142 are not limited to those shown, and may be changed to various angles and / or various sizes according to the internal conditions of the optical probe structure A. The first auxiliary mirror 141 and the second auxiliary mirror 142 may be changed to various angles and / or various sizes through an angle changing unit that changes an angle in response to an angle change signal of the control unit 170.

The third beam splitter 131 reflects the remaining light among the light output from the first beam splitter 121 to the third auxiliary mirror 151 adjacent to the reference mirror 133. The fourth auxiliary mirror 152 injects the measurement light for the second vibration noise reflected on the neighboring third auxiliary mirror 151 into the fourth beam splitter 132. The fourth beam splitter 132 reflects the second vibration noise measurement light reflected on the reference mirror 133 to the fourth auxiliary mirror 152. The third auxiliary mirror 151 injects the measurement light for the second vibration noise reflected on the fourth auxiliary mirror 152 into the third beam splitter 131. The first beam splitter 121 transmits the measurement light for the second vibration noise output from the third beam splitter 131 to the detector 160. This process represents the light path of arrow ⑤.

The third auxiliary mirror 151 and the fourth auxiliary mirror 152 may be provided to be fixed to face each other. The third auxiliary mirror 151 may be fixed at a constant angle to reflect the measurement light for the second vibration noise with respect to the fourth auxiliary mirror 152 and the third beam splitter 131. The fourth auxiliary mirror 152 may be fixed at a constant angle to reflect the measurement light for the second vibration noise with respect to the third auxiliary mirror 151 and the fourth beam splitter 132.

The third auxiliary mirror 151 and the fourth auxiliary mirror 152 are not limited to those illustrated, and may be changed to various angles and / or various sizes according to design conditions. The third auxiliary mirror 151 and the fourth auxiliary mirror 152 may be changed to various angles through an angle changing unit that changes an angle in response to the angle changing signal of the control unit 170.

2 shows another configuration of an optical interference system according to an embodiment.

Referring to FIG. 2, the second main interferometer 130 may include a third beam splitter 131. The second auxiliary interferometer 150 may include a third auxiliary mirror 151.

Specifically, the third beam splitter 131 reflects some of the light output from the first beam splitter 121 to the reference mirror 133. This process represents the optical path of the arrow ① in the second main interferometer 130.

The third beam splitter 131 injects the reference light reflected on the reference mirror 133 into the first beam splitter 121. The first beam splitter 121 transmits the reference light to the detector 160. This process represents the light path of arrow ③.

The third beam splitter 131 reflects the remaining light among the light output from the first beam splitter 121 to the third auxiliary mirror 151 adjacent to the reference mirror 133. The third beam splitter 131 reflects the measurement light for the second vibration noise reflected on the third auxiliary mirror 151 to the reference mirror 133. The third beam splitter 131 reflects the measurement light for the second vibration noise reflected on the reference mirror 133 to the third auxiliary mirror 151. The third beam splitter 131 injects the measurement light for the second vibration noise reflected on the third auxiliary mirror 151 into the first beam splitter 121. The first beam splitter 121 transmits the measurement light for the second vibration noise output from the third beam splitter 131 to the detector 160. This process represents the light path of arrow ⑤.

The third auxiliary mirror 151 may be fixedly provided to face each other with the third beam splitter 131. The third auxiliary mirror 151 is not limited to the illustrated figure, and may be changed to various sizes according to design conditions.

The sensing unit 160 detects the main interference light (main interference signal) synthesized by interfering with the measurement light through the optical paths of arrows ① and ② and the reference light through the optical paths of arrows ① and ③. The sensing unit 160 is a secondary interference light (secondary interference signal) synthesized by the interference of the measurement light for the first vibration noise through the optical path of arrow ④ and the measurement light for the second vibration noise through the optical path of arrow ⑤ ). The sensing unit 160 may include a CCD sensor or a CCD camera. The CCD camera shoots the main interference light and the auxiliary interference light. The image data of the main interference pattern and the secondary interference pattern photographed by the CCD camera are transmitted to the control unit 170.

The optical paths of arrows ①, ②, and ③ and the optical paths of arrows ④ and ⑤ are set farther than the interference distance between the light source 110 and the sample S and the reference mirror 133 to change and adjust the design so as not to interfere with each other. You can.

The control unit 170 includes a processor 171 and a memory 172.

The processor 171 is an image processor that processes image data for the received main interference pattern and the auxiliary interference pattern, and the main interference signal and the auxiliary signal through optical spectrum analysis on the received image data for the main interference pattern and the auxiliary interference pattern. It may include a digital signal processor for processing the position information in the optical axis direction of the interference signal.

The image processor may directly perform an inspection on the sample S by performing image analysis on the image data. The image processor displays the image data on the received main interference pattern and the auxiliary interference pattern on the display unit, so that the inspector can perform inspection on the sample S.

The digital signal processor is a secondary interference if the optical axis direction of the main interference signal and the secondary interference signal determined from the optical spectrum analysis of the main interference signal and the secondary interference signal is an optical axis direction including vibration signals and / or unwanted noise signals. The position of the main interference signal in the optical axis direction can be changed to the original position in the optical axis direction by the amount of change in the position in the optical axis direction.

The processor 171 changes the angle for changing the angles of the first auxiliary mirror 141 and / or the second auxiliary mirror 142 and / or the third auxiliary mirror 151 and / or the fourth auxiliary mirror 152 It may include a micro control unit (MCU) for generating a signal.

The memory 172 includes a program and / or data for the processor 171 to process image data, a program and / or data for changing and processing the optical axis position of the main interference signal, and a processor 131 to change the angle. And / or data for generating.

The memory 172 may temporarily store the result of processing the image data, and temporarily store the result of the change processing for the position of the main interference signal in the optical axis direction. For example, the memory 172 may include volatile memory such as S-RAM and D-RAM, as well as flash memory, ROM (Read Only Memory, ROM), and ERP-ROM (Erasable Programmable Read Only Memory). : EPROM).

3 shows an optical axis profile in an optical interference system according to an embodiment.

1 and 2, the sensing unit 160 detects the main interference signal synthesized by interference of the measurement light through the optical paths of arrows ① and ② and the reference light through the optical paths of arrows ① and ③. do. The sensing unit 160 detects the synthesized auxiliary interference signal by interfering with the measurement light for the first vibration noise through the optical path of arrow ④ and the measurement light for the second vibration noise through the optical path of arrow ⑤.

)와 보조 간섭신호(

)의 위치(P1, Q1)를 광축방향 위치상에 서로 구분되게 나타낼 수 있다.Referring to FIG. 3, the control unit 170 analyzes the main interference signal and the auxiliary interference signal detected by the detector 160 through optical spectrum analysis to determine the main interference signal (

) And auxiliary interference signal (

) Positions P1 and Q1 may be distinguished from each other on the optical axis position.

)와 보조 간섭신호(

)를 산출할 수 있다.Specifically, the control unit 170 uses the following <Equation 1> to the main interference signal (

) And auxiliary interference signal (

).

<Equation 1>

,

,

는 메인 간섭신호,

는 스펙트럼 밀도(source spectral density),

은 굴절률,

는 파수(wave number),

은 광이 광원부터 시작해서 샘플과 기준미러에 반사되어 돌아오는 경로에 대한 거리,

는 보조 간섭신호,

는 광이 광원부터 시작해서 샘플에 인접한 보조미러와 기준미러에 인접한 보조미러에 반사되어 돌아오는 경로에 대한 거리이다.here,

Is the main interference signal,

Is the source spectral density,

Silver refractive index,

Is the wave number,

The distance to the path where silver light returns from the light source to the sample and the reference mirror,

Is an auxiliary interference signal,

Is the distance to the path from which the light returns from reflecting back to the auxiliary mirror adjacent to the sample and the reference mirror starting from the light source.

)와 보조 간섭신호(

)를 푸리에 변환을 통한 거리에 관한 식으로 각각 산출할 수 있다.The control unit 170 uses the following <Equation 2> to the main interference signal (

) And auxiliary interference signal (

) Can be calculated by using the Fourier transform.

<Equation 2>

,

,

는 푸리에 변환을 통한 거리에 관한 메인 간섭신호,

는 간섭에 의한 envelope function,

은 굴절률,

은 광이 광원부터 시작해서 샘플과 기준미러에 반사되어 돌아오는 경로에 대한 거리,

는 푸리에 변환을 통한 거리에 관한 보조 간섭신호,

는 광이 광원부터 시작해서 샘플에 인접한 보조미러와 기준미러에 인접한 보조미러에 반사되어 돌아오는 경로에 대한 거리이다.here,

Is the main interference signal about the distance through Fourier transform,

Is the envelope function due to interference,

Silver refractive index,

The distance to the path where silver light returns from the light source to the sample and the reference mirror,

Is a secondary interference signal on the distance through Fourier transform,

Is the distance to the path from which the light returns from reflecting back to the auxiliary mirror adjacent to the sample and the reference mirror starting from the light source.

)와 보조 간섭신호(

)의 위치(P1, Q1)를 광축방향 위치상에 서로 구분되게 나타낼 수 있다. P1은

로 나타낼 수 있고 Q1은

로 나타낼 수 있다.As shown in FIG. 3, the control unit 170 is a main interference signal related to the distance through Fourier transform (

) And auxiliary interference signal (

) Positions P1 and Q1 may be distinguished from each other on the optical axis position. P1 is

Can be represented by and Q1 is

Can be represented as

4 is a diagram illustrating an optical axis profile including a vibration signal and / or an unwanted noise signal in an optical interference system according to an embodiment.

)와 보조 간섭신호(

)의 위치(P2, Q2)를 광축방향 위치상에 서로 구분되게 나타낼 수 있다.Referring to FIG. 4, the control unit 170 analyzes the main interference signal and the auxiliary interference signal detected by the detection unit 160 through optical spectrum analysis to determine the main interference signal (

) And auxiliary interference signal (

) Positions P2 and Q2 may be distinguished from each other on the optical axis position.

)와 보조 간섭신호(

)의 위치(P2, Q2)는 진동신호 및/또는 원하지 않는 잡음신호가 포함된 위치를 나타낸다.Main interference signal (

) And auxiliary interference signal (

), The positions P2 and Q2 indicate positions where vibration signals and / or unwanted noise signals are included.

)와 보조 간섭신호(

)를 산출할 수 있다.Specifically, the control unit 170 uses the following <Equation 3> main interference signal (

) And auxiliary interference signal (

).

<Equation 3>

,

,

는 메인 간섭신호,

는 스펙트럼 밀도(source spectral density),

은 굴절률,

는 파수(wave number),

은 광이 광원부터 시작해서 샘플과 기준미러에 반사되어 돌아오는 경로에 대한 거리,

는 보조 간섭신호,

는 광이 광원부터 시작해서 샘플에 인접한 보조미러와 기준미러에 인접한 보조미러에 반사되어 돌아오는 경로에 대한 거리,

는 진동신호 및/또는 원하지 않는 잡음신호에 대한 거리이다.here,

Is the main interference signal,

Is the source spectral density,

Silver refractive index,

Is the wave number,

The distance to the path where silver light returns from the light source to the sample and the reference mirror,

Is an auxiliary interference signal,

Is the distance to the path from which the light starts from the light source and reflects back to the secondary mirror adjacent to the sample and the secondary mirror adjacent to the reference mirror.

Is the distance to the vibration signal and / or the unwanted noise signal.

)와 보조 간섭신호(

)를 푸리에 변환을 통한 거리에 관한 식으로 각각 산출할 수 있다.The control unit 170 uses the following <Equation 4>, the main interference signal containing the vibration signal and / or unwanted noise signal (

) And auxiliary interference signal (

) Can be calculated by using the Fourier transform.

<Equation 4>

,

,

는 푸리에 변환을 통한 거리에 관한 메인 간섭신호,

는 간섭에 의한 envelope function,

은 굴절률,

은 광이 광원부터 시작해서 샘플과 기준미러에 반사되어 돌아오는 경로에 대한 거리,

는 푸리에 변환을 통한 거리에 관한 보조 간섭신호,

는 광이 광원부터 시작해서 샘플에 인접한 보조미러와 기준미러에 인접한 보조미러에 반사되어 돌아오는 경로에 대한 거리,

는 진동신호 및/또는 원하지 않는 잡음신호에 대한 거리이다.here,

Is the main interference signal about the distance through Fourier transform,

Is the envelope function due to interference,

Silver refractive index,

The distance to the path where silver light returns from the light source to the sample and the reference mirror,

Is a secondary interference signal on the distance through Fourier transform,

Is the distance to the path from which the light starts from the light source and reflects back to the secondary mirror adjacent to the sample and the secondary mirror adjacent to the reference mirror.

Is the distance to the vibration signal and / or the unwanted noise signal.

)와 보조 간섭신호(

)의 위치(P2, Q2)를 광축방향 위치상에 서로 구분되게 나타낼 수 있다. P2는

로 나타낼 수 있고, Q2는

로 나타낼 수 있다.As illustrated in FIG. 4, the control unit 170 may include a main interference signal related to a distance through a Fourier transform including a vibration signal and / or an unwanted noise signal (

) And auxiliary interference signal (

) Positions P2 and Q2 may be distinguished from each other on the optical axis position. P2 is

Can be represented by Q2

Can be represented as

5 shows an optical axis profile for changing the optical axis position of the main interference signal in the optical interference system according to an embodiment.

)와 보조 간섭신호(

)의 광축방향 위치가 진동신호 및/또는 원하지 않는 잡음신호가 포함된 광축방향 위치(P2, Q2)인지를 판단한다.Referring to FIG. 4, the control unit 170 determines the main interference signal determined from the optical spectrum analysis of the main interference signal and the auxiliary interference signal (

) And auxiliary interference signal (

It is determined whether the position in the optical axis direction of) is the optical axis direction position (P2, Q2) containing a vibration signal and / or an unwanted noise signal.

)와 보조 간섭신호(

)의 광축방향 위치가 진동신호 및/또는 원하지 않는 잡음신호가 포함된 광축방향 위치(P2, Q2)이면, 보조 간섭신호(

)의 광축방향 위치 변화량(Q2-Q1) 만큼 메인 간섭신호(

)의 광축방향 위치(P2)를 본래의 광축방향 위치(P1)로 변경한다.The control unit 170 is the main interference signal (

) And auxiliary interference signal (

), The optical axis direction position (P2, Q2) containing the vibration signal and / or unwanted noise signal, if the secondary interference signal (

) As much as the amount of position change in the optical axis direction (Q2-Q1).

), The optical axis position P2 is changed to the original optical axis position P1.

)의 광축방향 위치 변화량(Q2-Q1)을 산출할 수 있다.Specifically, the control unit 170 uses the following <Equation 5> auxiliary interference signal (

), The position change amount Q2-Q1 in the optical axis direction can be calculated.

<Equation 5>

는 보조 간섭신호의 광축방향 위치 변화량,

는 간섭에 의한 envelope function,

은 굴절률,

는 광이 광원부터 시작해서 샘플에 인접한 보조미러와 기준미러에 인접한 보조미러에 반사되어 돌아오는 경로에 대한 거리,

는 진동신호 및/또는 원하지 않는 잡음신호에 대한 거리이다.here,

Is the amount of change in the optical axis position of the auxiliary interference signal,

Is the envelope function due to interference,

Silver refractive index,

Is the distance to the path from which the light starts from the light source and reflects back to the secondary mirror adjacent to the sample and the secondary mirror adjacent to the reference mirror.

Is the distance to the vibration signal and / or the unwanted noise signal.

)의 광축방향 위치 변화량(

) 만큼 메인 간섭신호(

)의 광축방향 위치(P2)를 본래의 광축방향 위치(P1)로 변경한다.5, the control unit 170 is an auxiliary interference signal (

) The amount of change in position in the optical axis (

) As much as the main interference signal (

), The optical axis position P2 is changed to the original optical axis position P1.

)가 유동적일 수가 있으므로, 유동적이지 않은 보조 간섭신호(

)를 이용하여 보조 간섭신호(

)의 광축방향 위치 변화량(

)이 발생하면, 광학 프로브 구조물(A)내에서 진동신호 및/또는 원하지 않는 잡음신호가 발생한 것으로 판단하여 보조 간섭신호(

)의 광축방향 위치 변화량(

) 만큼 메인 간섭신호(

)의 광축방향 위치(P2)를 본래의 광축방향 위치(P1)로 변경할 수 있다.The control unit 170 is the main interference signal (S) when measuring the sample (S)

) May be fluid, so the auxiliary interference signal (

Auxiliary interference signal using ()

) The amount of change in position in the optical axis (

) Occurs, it is determined that a vibration signal and / or an unwanted noise signal has occurred in the optical probe structure (A), and the auxiliary interference signal (

) The amount of change in position in the optical axis

) As much as the main interference signal (

), The optical axis position P2 can be changed to the original optical axis position P1.

Such an optical interference system can improve the measurement accuracy by compensating the position of the main interference signal in the optical axis direction when a vibration signal and / or an unwanted noise signal occurs in the optical probe structure (A).

Meanwhile, the disclosed embodiments may be implemented in the form of a recording medium that stores instructions executable by a computer. Instructions may be stored in the form of program code, and when executed by a processor, may generate program modules to perform operations of the disclosed embodiments. The recording medium may be embodied as a computer-readable recording medium.

The computer-readable recording medium includes all kinds of recording media storing instructions that can be read by a computer. For example, there may be a read only memory (ROM), a random access memory (RAM), a magnetic tape, a magnetic disk, a flash memory, and an optical data storage device.

As described above, the disclosed embodiments have been described with reference to the accompanying drawings. Those skilled in the art to which the present invention pertains will understand that the present invention may be practiced in different forms from the disclosed embodiments without changing the technical spirit or essential features of the present invention. The disclosed embodiments are illustrative and should not be construed as limiting.

110: light source 120: first main interferometer
121: first beam splitter 122: second beam splitter
123: objective lens 130: second main interferometer
131: third beam splitter 132: fourth beam splitter
133: reference mirror 140: first auxiliary interferometer
141: first auxiliary mirror 142: second auxiliary mirror
150: second auxiliary interferometer 151: third auxiliary mirror
152: fourth auxiliary mirror 160: detection unit
170: control unit

Claims (5)

A light source that generates light;
A main interferometer for generating a main interference signal by interfering with the reference light reflected from the reference mirror and the measurement light reflected by the sample among the light generated from the light source;
Vibration noise reflected from the auxiliary mirror adjacent to the sample and the auxiliary mirror adjacent to the reference mirror to measure vibration signals and / or unwanted noise signals among light emitted from the light source and directed to the sample and light directed to the reference mirror An auxiliary interferometer that generates an auxiliary interference signal by interfering with the measurement light;
A sensing unit detecting the main interference signal and the auxiliary interference signal; And
If the optical axis direction positions of the main interference signal and the auxiliary interference signal determined from the optical spectrum analysis of the main interference signal and the auxiliary interference signal are optical axis directions including vibration signals and / or unwanted noise signals, the auxiliary signals And a control unit for changing the position of the main interference signal to the original position in the optical axis by the amount of change in the position of the interference signal in the direction of the optical axis. According to claim 1,
The auxiliary mirror adjacent to the sample is provided so that the two face each other to reflect the measurement light for vibration noise;
The auxiliary mirror adjacent to the reference mirror is provided with two or facing each other, or provided as one, an optical interference system for reflecting measurement light for vibration noise. According to claim 1,
The control unit calculates each of the main interference signal and the auxiliary interference signal by a formula related to a distance through a Fourier transform using the following equation.
<Mathematics>

,

here,

Is the main interference signal about the distance through Fourier transform,

Is the envelope function due to interference,

Silver refractive index,

The distance to the path where silver light returns from the light source to the sample and the reference mirror,

Is a secondary interference signal on the distance through Fourier transform,

Is the distance to the path from which the light returns from reflecting back to the auxiliary mirror adjacent to the sample and the reference mirror starting from the light source. According to claim 1,
The control unit calculates a main interference signal and an auxiliary interference signal including the vibration signal and / or the unwanted noise signal by using the following equations in terms of distance through Fourier transform.
<Mathematics>

,

here,

Is the main interference signal about the distance through Fourier transform,

Is the envelope function due to interference,

Silver refractive index,

The distance to the path where silver light returns from the light source to the sample and the reference mirror,

Is a secondary interference signal on the distance through Fourier transform,

Is the distance to the path from which the light starts from the light source and reflects back to the secondary mirror adjacent to the sample and the secondary mirror adjacent to the reference mirror.

Is the distance to the vibration signal and / or the unwanted noise signal. According to claim 1,
The control unit calculates an optical axis position change amount of the auxiliary interference signal using the following equation.
<Mathematics>

here,

Is the amount of change in the optical axis position of the auxiliary interference signal,

Is the envelope function due to interference,

Silver refractive index,

Is the distance to the path from which the light starts from the light source and reflects back to the secondary mirror adjacent to the sample and the secondary mirror adjacent to the reference mirror.

Is the distance to the vibration signal and / or the unwanted noise signal.

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