KR20030061643A - Phase shifting point diffraction interferometer using angled end-face optical fiber source - Google Patents

Phase shifting point diffraction interferometer using angled end-face optical fiber source Download PDF

Info

Publication number
KR20030061643A
KR20030061643A KR1020020002306A KR20020002306A KR20030061643A KR 20030061643 A KR20030061643 A KR 20030061643A KR 1020020002306 A KR1020020002306 A KR 1020020002306A KR 20020002306 A KR20020002306 A KR 20020002306A KR 20030061643 A KR20030061643 A KR 20030061643A
Authority
KR
South Korea
Prior art keywords
optical fiber
light
measurement
phase shift
fiber
Prior art date
Application number
KR1020020002306A
Other languages
Korean (ko)
Other versions
KR100470933B1 (en
Inventor
임쌍근
김학용
김승우
Original Assignee
(주) 인텍플러스
한국과학기술원
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by (주) 인텍플러스, 한국과학기술원 filed Critical (주) 인텍플러스
Priority to KR10-2002-0002306A priority Critical patent/KR100470933B1/en
Publication of KR20030061643A publication Critical patent/KR20030061643A/en
Application granted granted Critical
Publication of KR100470933B1 publication Critical patent/KR100470933B1/en

Links

Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01BMEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00Measuring instruments characterised by the use of optical techniques
    • G01B9/02Interferometers
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01BMEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00Measuring arrangements characterised by the use of optical techniques
    • G01B11/16Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
    • G01B11/161Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge by interferometric means

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Instruments For Measurement Of Length By Optical Means (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

PURPOSE: A phase shift point-diffraction interferometer is provided to improve reliability of measuring results by using a single mode optical fiber as a spherical wave light source. CONSTITUTION: A phase shift point-diffraction interferometer includes a neutral density filter(13) for adjusting quantity of monochromatic light radiated from a laser generator(11). Monochromatic light is split by a beam splitter(14) in such a manner that split light is incident into a measurement fiber(18) and a reference fiber(19). A tube type piezoelectric device(20) is provided to achieve a phase shift by converting a light route through lengthening the reference fiber(19). An end of the measurement fiber(18) opposite to an object(22) to be measured is inclined. Reflection wave reflected from an inclined surface of the measurement fiber(18) and a reference wave of the reference fiber(19) are overlapped with each other, thereby forming an interference pattern.

Description

경사단면 광섬유 광원을 이용한 위상천이 점회절 간섭계 {Phase shifting point diffraction interferometer using angled end-face optical fiber source}Phase shifting point diffraction interferometer using angled end-face optical fiber source}

본 발명은 물체의 표면 형상 측정에 이용되는 위상천이 점회절 간섭계에 관한 것으로, 특히 핀홀의 가공오차로 인한 구면 수차를 제거하여 측정결과의 신뢰성을 향상시키며 아울러 위상천이의 실현이 용이한 경사단면 광섬유 광원을 이용한 위상천이 점회절 간섭계에 관한 것이다.The present invention relates to a phase shift point diffraction interferometer used to measure the surface shape of an object. In particular, an inclined cross-section optical fiber, which improves the reliability of the measurement result by eliminating spherical aberration caused by the processing error of the pinhole. A phase shift point diffractometer using a light source is provided.

일반적으로, 광학부품이나 웨이퍼(wafer), 유리제품, 박막 등의 제조시 제작된 광학부품의 형상을 측정하기 위하여 간섭의 원리에 기초한 등색 무늬 차수 (fringe of equal chromatic order), 피조 간섭법(Fizeau Interferometry), 점회절 간섭법 등이 사용되고 있다.In general, the fringe of equal chromatic order based on the principle of interference, Fizeau to measure the shape of optical components manufactured during manufacturing of optical components, wafers, glass products, thin films, etc. Interferometry) and point diffraction interference methods are used.

점회절 간섭법은 핀홀 등의 점광원에서 나오는 구면파를 기준 파면으로 하는 간섭계로서, 다른 간섭계와 달리 기준 반사면이 필요없고 측정하고자 하는 렌즈나 미러 이외에는 광학계가 거의 불필요하다. 따라서, 간섭계 자체가 갖고 있는 시스템 오차가 적을 뿐만 아니라 잘 정의된 구면파를 기준 파면으로 삼기 때문에 다른 어떤 간섭계 보다도 측정 정밀도면에서 우수하다.The point diffraction interferometry is an interferometer which uses spherical waves from point light sources such as pinholes as reference waves. Unlike other interferometers, no reference reflecting surface is required and an optical system is almost unnecessary except for a lens or mirror to be measured. Therefore, the interferometer itself has less system error, and the measurement wave is superior to any other interferometer because it uses a well-defined spherical wave as a reference wavefront.

도 1은 상기와 같은 점회절 간섭법을 이용한 위상천이 점회절 간섭계의 일예인 미국 특허 등록 제5,548,403호를 나타낸 도면이다.FIG. 1 is a diagram showing US Patent No. 5,548,403, which is an example of a phase shift point diffractometer using the point diffraction interference method described above.

도면에 도시된 바와 같이, 광원(112)에서 출사된 단색광은 ND 필터(114)에 의해 광량이 조정되고, 이와같이 광량이 조정된 단색광은 광분할기(122)를 통해 제1 및 제2 반사경(124,128)으로 각각 분기되는데, 상기 제1 반사경(124)은 고정되어 있으며 제2 반사경(128)은 위상천이를 위해 압전소자(130)에 의해 유동 가능하게 장착되어 있다.As shown in the figure, the monochromatic light emitted from the light source 112 is adjusted by the ND filter 114, and the monochromatic light thus adjusted is controlled by the light splitter 122 to the first and second reflectors 124 and 128. The first reflector 124 is fixed and the second reflector 128 is movably mounted by the piezoelectric element 130 for phase shift.

상기와 같이 제1 및 제2 반사경(124,128)으로 분기된 단색광은 제1 및 제2 반사경(124,128)에 의해 반사되어 광분할기(122)로 되돌아온다. 이와같이 광분할기 (122)로 되돌아온 단색광은 광분할기(122)에 의해 반사되어 미러(126) 및 렌즈(134)를 통해 간섭판(136)의 핀홀을 통과하게 된다.As described above, the monochromatic light split into the first and second reflectors 124 and 128 is reflected by the first and second reflectors 124 and 128 and returned to the light splitter 122. The monochromatic light returned to the light splitter 122 is reflected by the light splitter 122 and passes through the pinhole of the interference plate 136 through the mirror 126 and the lens 134.

상기 간섭판(136)의 핀홀을 통과한 일측 반사광은 측정물(150)에 의해 다시 반사되어 간섭판(136)의 핀홀로 되돌아오는데, 이 반사광인 측정파면이 상기 간섭판(136)의 핀홀을 통해 CCD 카메라(158)로 진행하는 기준파면과 간섭을 일으켜 간섭무늬를 형성하게 된다. 따라서, 이 간섭무늬를 CCD 카메라(158)로 검출하면 광학부품의 형상을 측정할 수 있다.One side reflected light passing through the pinhole of the interference plate 136 is reflected back by the measurement object 150 to be returned to the pinhole of the interference plate 136, and the measurement wave surface, which is the reflected light, passes through the pinhole of the interference plate 136. Through this, interference with the reference wave surface proceeding to the CCD camera 158 forms an interference fringe. Therefore, when the interference fringe is detected by the CCD camera 158, the shape of the optical component can be measured.

그러나, 상기와 같은 종래의 위상천이 점회절 간섭계는 간섭판(136)의 핀홀의 가공오차에 따라 구면수차가 발생하게 되어 간섭계의 측정결과의 신뢰성을 확보하기 어렵다는 문제점이 있으며, 아울러 다수의 반사경(124,128)과 미러(126)를 통해 단색광을 반사시키고 그 과정중에 상기 제2 반사경(128)을 압전소자를 이용하여 위치이동시켜 위상천이를 실현함에 따라 그 구성이 복잡할 뿐만 아니라 간섭계의 소형화를 저해하는 요인으로 작용한다는 문제점이 있었다.However, the conventional phase shift point diffraction interferometer as described above has a problem that spherical aberration occurs according to the processing error of the pinhole of the interference plate 136, so that it is difficult to secure the reliability of the measurement result of the interferometer. Reflecting monochromatic light through 124,128 and mirror 126 and shifting the second reflector 128 using a piezoelectric element during the process to realize phase shift, not only the configuration is complicated, but also the miniaturization of the interferometer is inhibited. There was a problem that acts as a factor.

이에 본 발명은 상기와 같은 문제점을 해결하기 위해 발명된 것으로, 단일 모드 광섬유를 구면파 광원으로 사용함에 따라 핀홀의 가공오차로 인한 구면 수차를 제거하여 측정결과의 신뢰성을 향상시킬 수 있으며 아울러 간단한 구성으로 위상천이를 용이하게 구현할 수 있는 경사단면 광섬유 광원을 이용한 위상천이 점회절 간섭계를 제공하는 것을 그 목적으로 한다.Therefore, the present invention has been invented to solve the above problems, and by using a single mode optical fiber as a spherical wave light source, it is possible to remove spherical aberration due to processing error of the pinhole, thereby improving the reliability of the measurement result and also with a simple configuration. It is an object of the present invention to provide a phase shift point diffraction interferometer using an inclined cross-section optical fiber light source that can easily implement a phase shift.

상기와 같은 목적을 달성하기 위하여 본 발명은, 물체의 표면 형상 측정에 이용되는 위상천이 점회절 간섭계에 있어서: 레이저 발생장치에서 출사된 단색광의 광량을 조절하는 ND(Neutral Density) 필터와; 상기 ND 필터에 의해 광량이 조절된 단색광을 분기시켜 측정파면을 형성하기 위한 측정 광섬유(measurement fiber)와 기준파면을 형성하기 위한 기준 광섬유(reference fiber)의 일측 단부로 각각 입사시키는 광분할기와; 상기 기준 광섬유가 소정횟수 권선되어 있으며 수축 및 팽창에 따라 상기 기준 광섬유를 인장시켜 광경로의 변화를 통해 위상천이를 실현하는 튜브형 압전소자를 구비하되; 상기 측정물에 대향되는 측정 광섬유의 단부는 경사지게 형성되어 있으며, 상기 광섬유의 경사단면에는 광섬유에서 생성된 구면파를 투과시키고 측정물에 의해 반사된 반사파를 상측에 위치한 CCD 카메라로 반사시키는 광분할 코팅이 되어 있으며, 상기 측정 광섬유의 경사단면에서 반사되는 반사파와 기준 광섬유의 기준파가 중첩되어 간섭무늬를 형성하도록 기준파를 출사하는 상기 기준 광섬유의 단부가 측정 광섬유의 경사단면에 인접하게 장착된 것을 특징으로 한다.In order to achieve the above object, the present invention is a phase shift point diffraction interferometer used for measuring the surface shape of an object: an ND (Neutral Density) filter for adjusting the amount of light monochromatic light emitted from the laser generator; A light splitter which splits the monochromatic light whose light amount is controlled by the ND filter into one end of a measurement fiber for forming a measurement wavefront and a reference fiber for forming a reference wavefront; The reference optical fiber is wound a predetermined number of times and is provided with a tubular piezoelectric element for realizing the phase shift through the change of the optical path by tensioning the reference optical fiber in accordance with the contraction and expansion; An end portion of the measuring optical fiber opposite to the measurement object is formed to be inclined, and the inclined cross section of the optical fiber transmits spherical waves generated by the optical fiber and reflects the reflected wave reflected by the measuring object to a CCD camera located above. And an end portion of the reference optical fiber that emits a reference wave to overlap the reflected wave reflected from the inclined cross section of the measurement optical fiber and the reference wave of the reference optical fiber to form an interference fringe is mounted adjacent to the inclined cross section of the measuring optical fiber. It is done.

또한, 상기 위상천이 점회절 간섭계는: 상기 기준 광섬유로 입사되는 단색광의 광량을 조절하는 원형 가변 ND 필터를 더 포함하는 것을 특징으로 한다.The phase shift point diffraction interferometer may further include a circular variable ND filter configured to adjust the amount of monochromatic light incident on the reference optical fiber.

아울러, 상기 위상천이 점회절 간섭계는: 측정물의 앞에 설치되어 점광을 평행광으로 변환시키는 콜리메이터를 더 포함하는 것을 특징으로 한다.In addition, the phase shift point diffraction interferometer: It characterized in that it further comprises a collimator is installed in front of the workpiece to convert the point light into parallel light.

도 1은 종래의 위상천이 점회절 간섭계를 개략적으로 나타낸 도면,1 is a view schematically showing a conventional phase shift point diffraction interferometer,

도 2는 본 발명에 따른 위상천이 점회절 간섭계를 개략적으로 나타낸 도면,2 is a view schematically showing a phase shift point diffractometer according to the present invention;

도 3은 도 2에 도시된 측정 광섬유의 경사단면에 의한 광의 진행방향을3 is a view illustrating a propagation direction of light by an inclined cross section of the measurement optical fiber shown in FIG.

설명하기 위한 도면.Drawing for illustration.

도면의 주요부분에 대한 부호의 설명Explanation of symbols for main parts of the drawings

11 : 레이저 발생장치 12 : 미러11 laser generator 12 mirror

13 : ND 필터 14 : 광분할기13: ND filter 14: light splitter

15 : 원형 가변 ND 필터 16,17 : 입력 커플러15: circular variable ND filter 16, 17: input coupler

18 : 측정 광섬유 19 : 기준 광섬유18: measurement optical fiber 19: reference optical fiber

20 : 튜브형 압전소자 21 : 콜리메이터20 tube type piezoelectric element 21 collimator

22 : 측정물 23 : CCD 카메라22: workpiece 23: CCD camera

24 : 페룰24: ferrule

이하, 본 발명의 바람직한 일실시예를 첨부된 도면을 참조하여 상세히 설명하면 다음과 같다.Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

도 2는 본 발명에 따른 위상천이 점회절 간섭계를 개략적으로 나타낸 도면으로, 본 발명에 따른 위상천이 점회절 간섭계는 단색광을 출사하는 레이저 발생장치 (11)와, 상기 레이저 발생장치(11)에서 출사된 단색광을 반사시켜 광경로를 변환시키는 미러(12)와, 상기 미러(12)에 의해 반사된 단색광의 광량을 조절하는 ND (Neutral Density) 필터(13) 또는 편광판을 구비한다.2 is a view schematically showing a phase shift point diffraction interferometer according to the present invention, the phase shift point diffraction interferometer according to the present invention is a laser generating device 11 for emitting monochromatic light and the laser generating device 11 And a mirror 12 for changing the optical path by reflecting the monochromatic light, and an ND (Neutral Density) filter 13 or polarizing plate for adjusting the amount of light of the monochromatic light reflected by the mirror 12.

또한, 상기 ND 필터(13)에 의해 광량이 조절된 단색광을 50:50으로 분기시켜 입력 커플러(16)(17)를 통해 측정파면을 형성하기 위한 측정 광섬유(measurement fiber)(18)와 기준파면을 형성하기 위한 기준 광섬유(reference fiber)(19)의 일측 단부로 각각 입사시키는 광분할기(14)를 구비하는데, 상기 측정파면과 기준파면간의 입사 광량을 달리하여 간섭무늬의 가시도를 조절하기 위하여 상기 기준 광섬유 (19)로 입사되는 단색광은 원형 가변 ND 필터(15)를 통해 광량이 조정되어 기준 광섬유(19)로 입사된다.In addition, a measurement fiber 18 and a reference wavefront for splitting monochromatic light whose light amount is controlled by the ND filter 13 to 50:50 to form a measurement wavefront through the input coupler 16 and 17. And a light splitter 14 which is incident to one end of a reference fiber 19 to form a light source. In order to adjust the visibility of the interference fringe by varying the amount of incident light between the measurement wavefront and the reference wavefront The monochromatic light incident on the reference optical fiber 19 enters the reference optical fiber 19 by adjusting the amount of light through the circular variable ND filter 15.

아울러, 광경로를 변화시켜 위상천이가 발생하도록 상기 기준 광섬유(19)는 튜브형 압전소자(20)에 소정횟수 권선되어 있다. 즉, 튜브형 압전소자(20)가 팽창하여 직경이 변화하면 이 압전소자(20)에 권선되어 있는 기준 광섬유(19)가 인장되어 광경로를 변화시킴에 따라 위상천이를 용이하게 실현할 수 있다.In addition, the reference optical fiber 19 is wound around the tubular piezoelectric element 20 a predetermined number of times so that the phase shift occurs by changing the optical path. That is, when the tubular piezoelectric element 20 is expanded and its diameter is changed, the phase shift can be easily realized as the reference optical fiber 19 wound around the piezoelectric element 20 is tensioned to change the optical path.

한편, 상기 측정 광섬유(18)의 측정물(22)에 대향하는 단부는 도 3에 도시된 것처럼 경사지게 형성되어 있는데, 상기 광섬유(18)의 경사단면에는 광섬유(18)에서 생성된 구면파를 투과시키고 측정물(22)에 의해 반사된 반사파를 상측에 위치한 CCD 카메라(23)로 반사시키는 광분할기의 역활을 수행하도록 광분할 코팅이 되어 있다.Meanwhile, an end portion of the measuring optical fiber 18 opposite to the measurement object 22 is formed to be inclined as shown in FIG. 3, and the spherical wave generated by the optical fiber 18 is transmitted to the inclined end surface of the optical fiber 18. A light splitting coating is provided to perform the role of a light splitter that reflects the reflected wave reflected by the measurement object 22 to the CCD camera 23 located above.

아울러, 상기 측정 광섬유(18)의 경사단면에서 반사되는 반사파와 기준 광섬유(19)의 기준파가 중첩되어 간섭무늬를 형성하도록 기준파를 출사하는 기준 광섬유(19)의 단부가 측정 광섬유(18)의 경사단면에 인접하게 장착된다.In addition, an end of the reference optical fiber 19 that emits the reference wave so that the reflected wave reflected from the inclined cross section of the measurement optical fiber 18 and the reference wave of the reference optical fiber 19 overlaps to form an interference fringe. It is mounted adjacent to the inclined cross section.

또한, 점광을 평행광으로 변환시키는 콜리메이터(21)를 측정물(22)의 앞에 설치할 수 있는데, 이와같이 콜리메이터(21)를 장착하면 측정물(22)의 평면도 측정이 가능하다. 미설명된 도면부호 24는 경사단면 광섬유(18)를 감싸 보호하는 페룰을 나타낸 것이다.In addition, the collimator 21 which converts point light into parallel light can be provided in front of the measuring object 22. When the collimator 21 is mounted in this way, the planar measurement of the measuring object 22 is possible. Unexplained reference numeral 24 denotes a ferrule that surrounds and protects the inclined cross-section optical fiber 18.

상기와 같이 구성된 본 발명에 따른 위상천이 점회절 간섭계의 레이저 발생장치(11)에서 단색광이 출사되면, 이 단색광은 미러(12)에 의해 반사되어 ND 필터(13)로 입사된다. 이와같이 단색광이 입사되면 상기 ND필터(13)는 해당 단색광의 광량을 조절하여 광분할기(14)로 출사한다.When monochromatic light is emitted from the laser generator 11 of the phase shift point diffraction interferometer according to the present invention configured as described above, the monochromatic light is reflected by the mirror 12 and is incident to the ND filter 13. As such, when the monochromatic light is incident, the ND filter 13 emits the light to the light splitter 14 by adjusting the amount of light of the monochromatic light.

상기와 같이 광량이 조절된 단색광은 광분할기(14)에 의해 50:50으로 분기되어 입력 커플러(16)(17)를 통해 측정 광섬유(18)와 기준 광섬유(19)로 각각 입사되는데, 이때 기준 광섬유(19)로 입사되는 단색광의 광량은 원형 가변 ND 필터(15)에 의해 조정된다. 이는 측정 파면과 기준 파면간의 입사 광량을 달리하여 간섭무늬의 가시도를 조절하기 위한 것으로, 본 실시에에서는 4%∼100%인 측정물(22)의 반사도에 알맞게 기준파면의 광량을 조절할 수 있음에 따라 어떠한 상황에서도 양호한 간섭무늬를 얻을 수 있다.The monochromatic light whose light amount is adjusted as described above is branched at 50:50 by the light splitter 14 and is incident to the measurement optical fiber 18 and the reference optical fiber 19 through the input coupler 16 and 17, respectively, wherein the reference The light amount of monochromatic light incident on the optical fiber 19 is adjusted by the circular variable ND filter 15. This is to adjust the visibility of the interference fringe by varying the amount of incident light between the measurement wavefront and the reference wavefront, and in this embodiment, the amount of light on the reference wavefront can be adjusted to suit the reflectivity of the measuring object 22, which is 4% to 100%. Therefore, a good interference fringe can be obtained under any circumstances.

한편, 입력 커플러(16)를 통해 측정 광섬유(18)로 입사된 광은 단일 모드 광섬유(18)의 경사단면에서 측정물(22)을 향해 구면파로 전파해 나간다. 즉, 도 3에 도시된 것처럼 측정 광섬유(18)의 경사단면으로 부터 나오는 광선의 진행방향은 코어(18a)의 굴절률과 클래딩(18b)의 굴절률이 거의 같다고 했을 때() Snell의 법칙을 따르게 된다. 다시말해, 경사단면 광섬유(25)의 끝단이의 각도로 경사진 경우에 도면에 도시된 바와같이 광선은 단면 법선에 대해서의 각도로 진행하게 된다.On the other hand, the light incident on the measurement optical fiber 18 through the input coupler 16 propagates as spherical waves toward the measurement object 22 from the inclined cross section of the single mode optical fiber 18. That is, as shown in FIG. 3, when the propagation direction of the light beam exiting the inclined cross section of the measuring optical fiber 18 is almost equal to the refractive index of the core 18a and the refractive index of the cladding 18b ( Follow Snell's law. In other words, the end of the inclined cross section optical fiber 25 In the case of tilting at an angle of Will proceed at an angle of.

아울러, 경사단면 광섬유(18)의 굴절율이 1.45이고,가 29.19°일 경우에 Snell의 법칙,에 의해서의 값은 45°가 된다. 이와같이의 값이 45°가 되는 경우에는 측정물(22)에 의해 반사되어 되돌아오는 반사광선이 경사단면 광섬유(18)로부터 나오는 광선과 직각을 이루게 되는데, 이 반사광선이 기준 광섬유(19)에서 출사되는 기준광선과 간섭을 이룸에 따라 CCD 카메라(23)로 간섭무늬를 용이하게 관찰할 수 있다.In addition, the refractive index of the inclined cross section optical fiber 18 is 1.45, Snell's law, if is 29.19 ° By The value of becomes 45 °. like this When the value of becomes 45 °, the reflected light reflected by the measuring object 22 and returned is perpendicular to the light emitted from the inclined cross-section optical fiber 18, which is reflected from the reference optical fiber 19. By interfering with the reference light, the interference fringe can be easily observed with the CCD camera 23.

한편, 튜브형 압전소자(20)를 팽창시키면 압전소자(20)의 직경이 가변된다. 따라서, 압전소자(20)에 감겨있는 기준 광섬유(19)가 인장되어 광경로를 변화시키게 된다. 이와같이 본 실시예는 기준 광섬유(19)의 인장을 통한 광경로의 변화를 이용하여 위상천이를 용이하게 실현할 수 있다.On the other hand, when the tubular piezoelectric element 20 is expanded, the diameter of the piezoelectric element 20 is varied. Therefore, the reference optical fiber 19 wound around the piezoelectric element 20 is tensioned to change the optical path. As described above, the present embodiment can easily realize the phase shift by using the change of the optical path through the tension of the reference optical fiber 19.

상기와 같이 본 발명은 단일 모드 광섬유를 구면파 광원으로 사용함에 따라 핀홀의 가공오차로 인한 구면 수차를 제거하여 간섭계의 측정결과의 신뢰성을 향상시킬 수 있으며, 아울러 튜브형 압전소자에 광섬유를 권선하고 압전소자의 팽창에 따라 광섬유를 인장시켜 위상천이를 발생시킴에 따라 종래에 비해 간단한 구성으로 위상천이를 용이하게 실현할 수 있다.As described above, the present invention can improve the reliability of the measurement result of the interferometer by removing the spherical aberration caused by the processing error of the pinhole by using a single mode optical fiber as a spherical wave light source, and winding the optical fiber to the tubular piezoelectric element and According to the expansion of the optical fiber is tensioned to generate a phase shift, it is possible to easily realize the phase shift with a simple configuration compared to the conventional.

본 발명은 도면에 도시된 일실시예를 참고로 설명되었으나 이는 예시적인 것에 불과하며, 당해 기술분야에 통상의 지식을 지닌자라면 이로부터 다양한 변형 및 균등한 타실시예가 가능하다는 점을 이해할 것이다. 따라서, 본 발명의 진정한 기술적 보호범위는 첨부된 특허청구범위에 의해서만 정해져야 할 것이다.Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary, and it will be understood by those skilled in the art that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention should be defined only by the appended claims.

Claims (3)

물체의 표면 형상 측정에 이용되는 위상천이 점회절 간섭계에 있어서:In a phase shift point diffractometer used to measure the surface shape of an object: 레이저 발생장치(11)에서 출사된 단색광의 광량을 조절하는 ND (Neutral Density) 필터(13)와;An ND (Neutral Density) filter 13 for adjusting the amount of monochromatic light emitted from the laser generator 11; 상기 ND 필터(13)에 의해 광량이 조절된 단색광을 분기시켜 측정파면을 형성하기 위한 측정 광섬유(measurement fiber)(18)와 기준파면을 형성하기 위한 기준 광섬유(reference fiber)(19)의 일측 단부로 각각 입사시키는 광분할기(14)와;One end of a measurement fiber 18 for forming a measurement wavefront by branching monochromatic light whose light amount is controlled by the ND filter 13 and a reference fiber 19 for forming a reference wavefront A light splitter 14 for injecting the light into each other; 상기 기준 광섬유(19)가 소정횟수 권선되어 있으며 수축 및 팽창에 따라 상기 기준 광섬유(19)를 인장시켜 광경로의 변화를 통해 위상천이를 실현하는 튜브형 압전소자(20)를 구비하되;The reference optical fiber 19 is wound a predetermined number of times and is provided with a tubular piezoelectric element 20 for tensioning the reference optical fiber 19 in accordance with the contraction and expansion to realize a phase shift through the change of the optical path; 상기 측정물(22)에 대향되는 측정 광섬유(18)의 단부는 경사지게 형성되어 있으며, 상기 광섬유(18)의 경사단면에는 광섬유(18)에서 생성된 구면파를 투과시키고 측정물(22)에 의해 반사된 반사파를 상측에 위치한 CCD 카메라(23)로 반사시키는 광분할 코팅이 되어 있으며, 상기 측정 광섬유(18)의 경사단면에서 반사되는 반사파와 기준 광섬유(19)의 기준파가 중첩되어 간섭무늬를 형성하도록 기준파를 출사하는 상기 기준 광섬유(19)의 단부가 측정 광섬유(18)의 경사단면에 인접하게 장착된 것을 특징으로 하는 경사단면 광섬유 광원을 이용한 위상천이 점회절 간섭계.An end portion of the measurement optical fiber 18 opposite to the measurement object 22 is formed to be inclined, and the oblique end surface of the optical fiber 18 transmits spherical waves generated by the optical fiber 18 and is reflected by the measurement object 22. It is a light split coating for reflecting the reflected wave to the CCD camera 23 located on the upper side, and the reflected wave reflected from the inclined cross section of the measurement optical fiber 18 and the reference wave of the reference optical fiber 19 overlap to form an interference pattern. A phase shift point diffraction interferometer using an inclined cross-section optical fiber light source, characterized in that an end portion of the reference optical fiber (19) emitting a reference wave is mounted adjacent to the inclined cross section of the measurement optical fiber (18). 제 1 항에 있어서, 상기 위상천이 점회절 간섭계는:2. The system of claim 1, wherein the phase shift point diffractometer is: 상기 기준 광섬유(19)로 입사되는 단색광의 광량을 조절하는 원형 가변 ND 필터(15)를 더 포함하는 것을 특징으로 하는 경사단면 광섬유 광원을 이용한 위상천이 점회절 간섭계.And a circular variable ND filter (15) for adjusting the amount of monochromatic light incident on the reference optical fiber (19). 제 1 항 또는 제 2 항에 있어서, 상기 위상천이 점회절 간섭계는:3. The method of claim 1 or 2, wherein the phase shift point diffractometer is: 측정물(22)의 앞에 설치되어 점광을 평행광으로 변환시키는 콜리메이터(21)를 더 포함하는 것을 특징으로 하는 경사단면 광섬유 광원을 이용한 위상천이 점회절 간섭계.And a collimator (21) installed in front of the measurement object (22) to convert point light into parallel light.
KR10-2002-0002306A 2002-01-15 2002-01-15 Phase shifting point diffraction interferometer using angled end-face optical fiber source KR100470933B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
KR10-2002-0002306A KR100470933B1 (en) 2002-01-15 2002-01-15 Phase shifting point diffraction interferometer using angled end-face optical fiber source

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
KR10-2002-0002306A KR100470933B1 (en) 2002-01-15 2002-01-15 Phase shifting point diffraction interferometer using angled end-face optical fiber source

Publications (2)

Publication Number Publication Date
KR20030061643A true KR20030061643A (en) 2003-07-22
KR100470933B1 KR100470933B1 (en) 2005-03-08

Family

ID=32218116

Family Applications (1)

Application Number Title Priority Date Filing Date
KR10-2002-0002306A KR100470933B1 (en) 2002-01-15 2002-01-15 Phase shifting point diffraction interferometer using angled end-face optical fiber source

Country Status (1)

Country Link
KR (1) KR100470933B1 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100465784B1 (en) * 2002-05-03 2005-01-13 한국과학기술원 Point Diffraction Interferometer and Measurement Method Using Inclined Optical Fiber Source
CN103217104A (en) * 2013-03-15 2013-07-24 中国计量学院 Non-guide measurement device and method of point diffraction three-dimensional absolute displacement
KR101628761B1 (en) * 2015-03-06 2016-06-09 (주) 인텍플러스 surface shape measuring appatstus using asymmetric interferometer
WO2021086801A1 (en) * 2019-10-28 2021-05-06 Kla Corporation Common path mode fiber tip diffraction interferometer for wavefront measurement

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103267485A (en) * 2013-03-20 2013-08-28 中国计量学院 Point-diffraction three-dimensional absolute displacement measuring method

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59148832A (en) * 1983-02-15 1984-08-25 Hitachi Ltd Optical fiber type underwater sound detector
JPS60177207A (en) * 1984-02-24 1985-09-11 Toshiba Corp Strain measuring device
PT888522E (en) * 1996-03-22 2001-10-30 Univ Loughborough PROCESS AND APPARATUS FOR THE MEDICATION OF THE OBJECT FORM
KR100415477B1 (en) * 2001-05-22 2004-01-24 한국과학기술원 Coordinate Determination Method and System in 3D Space Using Optical Phase Interferometry

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100465784B1 (en) * 2002-05-03 2005-01-13 한국과학기술원 Point Diffraction Interferometer and Measurement Method Using Inclined Optical Fiber Source
CN103217104A (en) * 2013-03-15 2013-07-24 中国计量学院 Non-guide measurement device and method of point diffraction three-dimensional absolute displacement
KR101628761B1 (en) * 2015-03-06 2016-06-09 (주) 인텍플러스 surface shape measuring appatstus using asymmetric interferometer
WO2021086801A1 (en) * 2019-10-28 2021-05-06 Kla Corporation Common path mode fiber tip diffraction interferometer for wavefront measurement
US11333487B2 (en) 2019-10-28 2022-05-17 Kla Corporation Common path mode fiber tip diffraction interferometer for wavefront measurement

Also Published As

Publication number Publication date
KR100470933B1 (en) 2005-03-08

Similar Documents

Publication Publication Date Title
US5923425A (en) Grazing incidence interferometry for measuring transparent plane-parallel plates
US6344898B1 (en) Interferometric apparatus and methods for measuring surface topography of a test surface
KR100225923B1 (en) Phase shifting diffraction interferometer
US7440114B2 (en) Off-axis paraboloid interferometric mirror with off focus illumination
JP2004040067A (en) Method of detecting focus and imaging system having focus detecting system
US7095510B2 (en) Point diffraction interferometer with enhanced contrast
JPH05210006A (en) Method and apparatus for generating multiple light beam of multiple wave- length interferometer
KR100470933B1 (en) Phase shifting point diffraction interferometer using angled end-face optical fiber source
US6909510B2 (en) Application of the phase shifting diffraction interferometer for measuring convex mirrors and negative lenses
JP4262087B2 (en) Multi-axis interferometer
KR20030086020A (en) Point Diffraction Interferometer and Measurement Method Using Inclined Optical Fiber Source
CN109458959A (en) A kind of change inclination angle phase shift grazing-incidence interferometer measuring device and method
US5438412A (en) Phase conjugate interferometer for testing paraboloidal mirror surfaces
US20060048545A1 (en) Apparatus for generating an optical interference pattern
US6873762B1 (en) Fabrication of fiber optic grating apparatus and method
KR20190106405A (en) Parallel light generating arraratus for large area
JP6371120B2 (en) measuring device
RU2760920C1 (en) Standardless highly coherent interferometer
RU2313066C1 (en) Interferometric mode of measuring the thickness and the values of refraction of transparent objects
Kihm et al. Fiber optic diffraction interferometer for testing spherical mirrors
KR101464695B1 (en) Multi-interference phase interferometer with simultaneous measurement functions
Han et al. Retrace error for the measurement of a long-radius optic
JP2000018918A (en) Laser interference apparatus for detecting moving quantity of movable body
KR100422378B1 (en) Fizeau interferometer using angled end-face optical fiber source
JP2000097650A (en) Device for measuring shape of aspheric surface

Legal Events

Date Code Title Description
A201 Request for examination
E902 Notification of reason for refusal
E701 Decision to grant or registration of patent right
GRNT Written decision to grant
FPAY Annual fee payment

Payment date: 20130123

Year of fee payment: 9

FPAY Annual fee payment

Payment date: 20140117

Year of fee payment: 10

FPAY Annual fee payment

Payment date: 20150115

Year of fee payment: 11

FPAY Annual fee payment

Payment date: 20160119

Year of fee payment: 12

FPAY Annual fee payment

Payment date: 20170120

Year of fee payment: 13

FPAY Annual fee payment

Payment date: 20180103

Year of fee payment: 14

FPAY Annual fee payment

Payment date: 20190110

Year of fee payment: 15

FPAY Annual fee payment

Payment date: 20200109

Year of fee payment: 16