JPH11304417A - Optical interference fringe measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical interference fringe measuring device capable of obtaining plural interference fringe images from the measured light and the reference light at the same time without providing a mechanically movable part. SOLUTION: The light from a light source 1 is divided by a beam splitter 3 into plural spectral measured light 9A-9C as the reflected light from a surface 4 to be measured and plural spectral reference light 11A-11C having a different phase at the same time, and each spectral reference light 11A-11C combined with each spectral measured light 9A-9C forms plural optical interference fringes, and photoelectric converting means 19A-19C for taking the interference fringe optical information of an optical interference system are provided in each optical interference system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical interference fringe measuring apparatus, and more particularly, to an optical interference fringe measuring apparatus using a phase shift method capable of performing high-accuracy analysis.

[0002]

2. Description of the Related Art As is well known, in an optical interference fringe measuring apparatus for analyzing an interference fringe generated by light interference to analyze a shape of a surface to be measured, a reference surface is moved in an optical axis direction to thereby adjust a phase of the reference light. Is changed, and a plurality of interference fringe images before and after the movement are analyzed to determine the shape of the surface to be measured (for example, see Japanese Patent Application Laid-Open No.
No. 59709).

FIG. 5 shows an optical system of a conventional optical interference fringe measuring apparatus using such a phase shift method. Coherent light from a light source B, which is made parallel by a lens A, passes through a beam splitter C. The light is reflected by the surface D to be measured, reflected by the beam splitter C, and input to a camera F such as a CCD element by an imaging lens E. A reference surface member G that is moved in the optical axis direction of the measurement light is located between the beam splitter C and the surface D to be measured.
The reflected light from the surface D to be measured is interfered by the interposition of.

That is, in such a conventional optical interference fringe measuring apparatus, since the phase of the reference light is shifted by a change in the position of the reference surface member G in the optical axis direction, the interference fringes before and after the movement of the reference surface member G are detected. The shape of the surface D to be measured can be known by taking the camera F into the processing device H and analyzing it.

[0005]

However, according to the optical interference fringe measuring apparatus having such a configuration, the reference plane member G
Since the phase of the reference light is shifted by the movement of the reference surface member G, the apparatus tends to be expensive due to the precise movement of the reference surface member G, and for actual analysis, a plurality of sheets are required every time the reference surface member G moves. It is necessary to take in the interference fringe images sequentially into the processing device, so that there is a disadvantage that the analysis work takes time. For this reason, if there is an environmental change such as air fluctuation, mechanical vibration, or temperature change at the time of capturing each interference fringe image, the interference fringe image changes due to these effects. Of course, in this optical interference fringe measurement apparatus, since the interference fringe images differing in time due to the movement of the reference surface member G are taken in, the analysis method itself could not measure a high-speed moving body.

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the conventional optical interference fringe measuring apparatus, the object of the present invention is that there is no mechanical movable part, and a plurality of interference fringe images between the measuring light and the reference light can be obtained. An object is to obtain an optical interference fringe measuring device which can be obtained at the same time.

[0007]

In order to achieve this object, the present invention provides a beam splitter which converts light from a light source into a plurality of light beams having different phases from a plurality of spectral measurement light beams reflected from a surface to be measured. Photoelectric conversion means which simultaneously divides the spectral reference light into a plurality of spectral reference lights, forms a plurality of optical interference systems with the respective spectral reference lights combined with the respective spectral measurement lights, and captures interference fringe optical information of these optical interference systems Is proposed in each optical interference system.

In the following description of a preferred embodiment of the present invention, 1) a beam splitter for splitting parallel light from a light source into light projected onto a surface to be measured and reference light, and the measurement reflected from the surface to be measured A plurality of measurement light splitters for decomposing light into a plurality of spectral measurement lights, a reference light splitter for decomposing the reference light into a plurality of spectral reference lights, and another spectral reference light interposed in at least one of the spectral reference lights An optical medium that generates reference light having a phase different from that of the optical medium or an optical medium that is interposed in at least one of the spectral measurement lights and generates measurement light having a phase different from the phase of the other spectral measurement light; A plurality of interference unit splitters constituting a plurality of optical interference systems by combining the spectral reference light with the measurement light; and a unit for capturing and storing interference fringe optical information of these optical interference systems. 2) a beam splitter that divides parallel light from a light source into projection light onto a surface to be measured and reference light, and a plurality of measurement lights that decompose the measurement light reflected from the surface to be measured into a plurality of spectral measurement lights A splitter, a reference light splitter that splits the reference light into a plurality of spectral reference lights, and a liquid crystal phase that is interposed in at least one of the spectral reference lights and generates a reference light having a phase different from the phase of another spectral reference light. A liquid crystal phase shift plate that generates measurement light having a phase different from the phase of the other spectral measurement light interposed in at least one of the shift plate or the spectral measurement light, and combining the spectral reference light with each of the spectral measurement lights. A configuration including a plurality of interference unit splitters constituting a plurality of optical interference systems, and a unit for capturing and storing interference fringe optical information of the optical interference systems; 3) parallel light from a light source to a surface to be measured; A beam splitter that divides the measurement light reflected from the surface to be measured into a plurality of spectral measurement lights, a beam splitter that divides the measurement light reflected from the surface to be measured into a plurality of spectral measurement lights, A reference light splitter, and an optical wedge that is interposed in at least one of the spectral reference lights and generates a reference light having a phase different from the phase of another spectral reference light, or another optical wedge that is interposed in at least one of the spectral measurement lights. An optical wedge that generates measurement light having a phase different from the phase of the spectral measurement light; a plurality of interference unit splitters that form a plurality of optical interference systems by combining the spectral reference light with each of the spectral measurement lights; Means for capturing and storing interference fringe optical information of an interference system; 4) a beam splitter for splitting parallel light from a light source into projection light onto a surface to be measured and reference light; A plurality of measurement light splitters for decomposing the measurement light reflected from the measurement surface into a plurality of spectral measurement lights, a reference light splitter for decomposing the reference light into a plurality of spectral reference lights, and at least one of the spectral reference lights At least one pair of a reference light splitter and an optical path length mirror interposed so as to have an optical path length different from the optical path length of another spectral reference light to obtain spectral reference light having a different phase, or at least one of the spectral measurement light And at least one set of measurement light splitters and optical path length mirrors that have different optical path lengths from the optical path lengths of the other spectroscopic measurement lights, so that the spectroscopic measurement lights have different phases. A plurality of interfering unit splitters that form a plurality of optical interference systems by combining light, and a unit that captures and stores interference fringe optical information of these optical interference systems. That configuration is described.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS. FIG. 1 shows an optical system of an optical interference fringe measuring apparatus according to a first embodiment of the present invention. Coherent light emitted from a light source 1 is converted into a parallel light beam by a lens 2.

This parallel light beam is split by a beam splitter 3 located on the optical axis into a projection light to the measured surface 4 and a reference light for reflected light from the measured surface 4. The light projected onto the surface 4 to be measured is reflected by the surface 4 to be measured, reflected again by the beam splitter 3, and then totally reflected by the measuring light reflecting mirror 5 to become measuring light. The measurement light splitters 6 and 7 and the first total reflection mirror 8 split the light into three systems of spectral measurement light 9A, 9B and 9C.

That is, the measuring light from the measuring light reflecting mirror 5 is divided into reflected light and transmitted light while passing through the first measuring light splitter 6, and the reflected light from the first measuring light splitter 6 is converted into the first spectral measuring light. 9A, the transmitted light of the first measurement light splitter 6 is similarly divided into reflected light and transmitted light by the second measurement light splitter 7, and the reflected light of the second measurement light splitter 7 is converted to the second spectral measurement light 9B. Become. Further, the transmitted light of the second measurement light splitter 7 is reflected by the first total reflection mirror 8, and becomes the third spectrum measurement light 9C parallel to the first spectrum measurement light 9A and the second spectrum measurement light 9B.

On the other hand, the reference light, which is the reflected light from the beam splitter 3, is inverted by an inverting optical lens 1 for inverting the wavefront from side to side.
0, and the above-mentioned respective spectroscopic measurement lights 9A, 9B, 9C
, Three systems of spectral reference beams 11A, 11B, 11
C. That is, the reference light is the first reference light splitter 1
2, the light is divided into reflected light and transmitted light, and the reflected light from the first reference light splitter 12 is used as the first spectral reference light 11A. The transmitted light from the first reference light splitter 12 is used as the second reference light splitter. At 13 the light is similarly divided into reflected light and transmitted light,
The reflected light of the second reference light splitter 13 is the second spectral reference light 1
1B, the first refraction medium 14 having a specific refractive index is located in the optical path of the second spectral reference light 11B. Also,
The transmitted light of the second reference light splitter 13 is reflected by the second total reflection mirror 15 and becomes the third spectral reference light 11C parallel to the first spectral reference light 11A and the second spectral reference light 11B.
A second refraction medium 16 having a refractive index different from that of the first refraction medium 14 is located in the optical path of the third spectral reference light 11C.

The first spectral measurement light 9A and the first spectral reference light 11A that intersect at substantially right angles are the first spectral measurement light 9A and the first spectral reference light 11A located at the intersection.
The interference fringe image information obtained through interference through the interference unit splitter 17A is captured by a first photoelectric conversion camera 19A such as a first imaging lens 18A and a CCD element. Similarly,
The second spectral measurement light 9B and the second spectral reference light 11B pass through a second interference part splitter 17B located at the intersection of the second spectral measurement light 9B and the third spectral measurement light 9C and the third spectral reference light 11C.
Are the third interference unit splitters 17 located at their intersections.
The light is interfered with each other via C, and is captured by the second photoelectric conversion camera 19B and the third photoelectric conversion camera 19C combined with the second imaging lens 18B and the third imaging lens 18C. In addition, the first to third photoelectric conversion cameras 19A to 19A
The three pieces of interference fringe information captured in C are stored in the storage device 20, and the result of calculating the shape from the stored plurality of pieces of interference fringe information is reproduced on the monitor 21.

The optical interference fringe measuring apparatus according to the first embodiment is
With the above-described configuration, a plurality of systems of spectral reference beams 11A to 11A having different phases with respect to the projection light from the light source 1.
C are made simultaneously, and these spectral reference beams 11A to 11C
Are spectral measurement lights 9A to 9 composed of light reflected from the surface 4 to be measured.
C, the interference fringe information is simultaneously captured by the plurality of photoelectric conversion cameras 19A to 19C, stored in the storage device 20, and compared with the plurality of pieces of interference fringe image information to obtain the measured surface 4 Is analyzed. Therefore, the optical interference fringe measuring apparatus of the first embodiment has not only a mechanically movable part requiring precision processing but also a plurality of spectral reference beams 11A having different phases combined with the plurality of spectral measurement beams 9A to 9C. Since a plurality of optical interference systems are simultaneously configured at up to 11C, measurement of a high-speed moving object is also possible, and an optical interference fringe measuring apparatus which is less affected by environmental changes such as air fluctuations, mechanical vibrations, and temperature changes. Can be obtained.

In the first embodiment described above, the second spectral reference beam 11B and the third spectral reference beam 11C are formed using the refractive media 14 and 16 having different refractive indexes. Reference numerals 14 and 16 denote phase shifts by substituting a plurality of thickness media having the same refractive index and different thicknesses, respectively, so that the optical path lengths of the second and third spectral reference beams 11B and 11C are different. , The same effect can be obtained. Here, an arbitrary phase shift can be obtained by adjusting or selecting the refractive index and thickness of the refraction media 14 and 16.

FIG. 2 shows an optical interference fringe measuring apparatus according to a second embodiment of the present invention, and the same components as those in the first embodiment are denoted by the same reference numerals as in FIG. That is, the coherent light emitted from the light source 1 is converted into a parallel light beam by the lens 2, and is split by the beam splitter 3 into the light projected on the surface 4 to be measured and the reference light for the light reflected from the surface 4 to be measured. The reflected light from the surface to be measured 4 is reflected again by the beam splitter 3 and then totally reflected by the measuring light reflecting mirror 5 to be divided into three systems by the two measuring light splitters 6 and 7 and the first total reflecting mirror 8. These are the spectral measurement lights 9A, 9B, and 9C.

The reference light reflected from the beam splitter 3 is passed through an inverting optical lens 10 for inverting the wavefront to the left and right, and is then subjected to three systems of spectral reference by reference light splitters 12 and 13 and a second total reflection mirror 15. Light 11A, 11
B, 11C. Further, each of the spectroscopic measurement lights 9A, 9B,
The spectral reference beams 11A, 11B, and 11C corresponding to 9C correspond to the interfering unit splitters 17A and 17A located at their intersections.
7B and 17C, and the obtained interference fringe image information is stored in a plurality of imaging lenses 18A, 18B and 18C.
And are captured by the photoelectric conversion cameras 19A, 19B, and 19C. And each photoelectric conversion camera 19A, 19B, 19
The three pieces of interference fringe information captured in C are stored in a storage processing device 20 having a storage unit and a processing unit, and the result of calculating a shape from the stored plurality of pieces of interference fringe information is reproduced on a monitor 21. This is the same as in the first embodiment.

The optical interference fringe measuring apparatus according to the second embodiment is characterized by the second spectral reference beam 11B and the third spectral reference beam 11C.
Liquid crystal phase shift plates 14 respectively incorporated in
A and 16A, the reference light of the second spectral reference light 11B and the reference light of the third spectral reference light 11C are different in phase by the liquid crystal phase shift plates 14A and 16A replaced by the refraction media 14 and 16, respectively. Is done.

The optical interference fringe measuring apparatus according to the second embodiment is
With the above-described configuration, a plurality of systems of spectral reference beams 11A to 11A having different phases with respect to the projection light from the light source 1.
C are made simultaneously, and these spectral reference beams 11A to 11C
Are spectral measurement lights 9A to 9 composed of light reflected from the surface 4 to be measured.
C, respectively, and these pieces of interference fringe information are simultaneously captured by a plurality of photoelectric conversion cameras, stored in the storage device 20, and compared with a plurality of pieces of interference fringe image information to determine the surface of the surface 4 to be measured. The shape is analyzed. In this case, by incorporating the liquid crystal phase shift plates 14A and 16A, the spectral reference light 1
Since the phases of the reference beams 1A to 11C are different, the same operation and effect as in the first embodiment can be expected in the configuration of the second embodiment.

FIG. 3 shows an optical interference fringe measuring apparatus according to a third embodiment of the present invention. The same components as those in the first and second embodiments described above are denoted by the same reference numerals as in FIG. Shown. That is, the coherent light emitted from the light source 1 is converted into a parallel light beam by the lens 2, and is split by the beam splitter 3 into the light projected on the surface 4 to be measured and the reference light for the light reflected from the surface 4 to be measured. The reflected light from the surface to be measured 4 is reflected again by the beam splitter 3 and then totally reflected by the measuring light reflecting mirror 5 to be divided into three systems by the two measuring light splitters 6 and 7 and the first total reflecting mirror 8. These are the spectral measurement lights 9A, 9B, and 9C.

The reference light reflected from the beam splitter 3 is passed through an inverting optical lens 10 for inverting the wavefront to the left and right, and then is subjected to three systems of spectral reference by reference light splitters 12 and 13 and a second total reflection mirror 15. Light 11A, 11
B, 11C. Further, each of the spectroscopic measurement lights 9A, 9B,
The spectral reference beams 11A, 11B, and 11C corresponding to 9C correspond to the interfering unit splitters 17A and 17A located at their intersections.
7B and 17C, and the obtained interference fringe image information is stored in a plurality of imaging lenses 18A, 18B and 18C.
And the images are captured by the photoelectric conversion cameras 19A, 19B, and 19C. And each photoelectric conversion camera 19A, 1
The three interference fringe information taken in 9B and 19C are stored in the storage processing device 20, and the result of calculating the shape from the stored plurality of pieces of interference fringe information is reproduced on the monitor 21 in the first embodiment and the second embodiment. This is the same as in the case of the second embodiment.

The optical interference fringe measuring apparatus according to the third embodiment is characterized by the second spectral reference beam 11B and the third spectral reference beam 11C.
Optical wedges 14B and 16 respectively incorporated in
B, and these optical wedges 1 replaced by the refraction media 14 and 16 and the liquid crystal phase shift plates 14A and 16A.
The optical path lengths of the second spectral reference light 11B and the third spectral reference light 11C are made different by 4B and 16B, and as a result, the phases of the second spectral reference light 11B and the third spectral reference light 11C are made different. .

The optical interference fringe measuring apparatus according to the third embodiment is
With the above-described configuration, a plurality of systems of spectral reference beams 11A to 11A having different phases with respect to the projection light from the light source 1.
C are made simultaneously, and these spectral reference beams 11A to 11C
Are spectral measurement lights 9A to 9 composed of light reflected from the surface 4 to be measured.
C, respectively, and these pieces of interference fringe information are simultaneously captured by a plurality of photoelectric conversion cameras, stored in the storage device 20, and compared with a plurality of pieces of interference fringe image information to determine the surface of the surface 4 to be measured. The shape is analyzed. In this case, the spectral reference beams 11A to 11A to
Since the phase of the reference light of 11C is different, the same operation and effect as those of the first and second embodiments can be expected even with the configuration of the third embodiment.

FIG. 4 shows an optical interference fringe measuring apparatus according to a fourth embodiment of the present invention, and the same components as those in the above-described embodiments are denoted by the same reference numerals as in FIG.
That is, the coherent light emitted from the light source 1
The beam splitter 3 divides the beam into a parallel light beam, and the beam splitter 3 divides the beam into projection light onto the surface 4 to be measured and reference light with respect to the light reflected from the surface 4 to be measured. After being reflected by the measuring light reflecting mirror 5, the two measuring light splitters 6 and 7 and the first total reflecting mirror 8 separate the three sets of spectral measuring light 9 A,
9B and 9C.

The reference light reflected from the beam splitter 3 is made into three systems of spectral reference lights 11A, 11B and 11C having different optical path lengths. That is, the first spectral reference light 11A, the second spectral reference light 11B, and the third spectral reference light 11
C has reference light splitters 22A, 22 at different positions.
B, second total reflection mirror 22C and reference beam splitter 22
A, 22B, and optical path length mirrors 23A to 23C that reflect the reference light from the second total reflection mirror 22C toward the corresponding interference unit splitters 17A, 17B, and 17C are provided.
These reference light splitters 22A and 22B, the second total reflection mirror 22C, and the optical path length mirrors 23A to 23C are different from each other with respect to the first spectral reference light 11A, the second spectral reference light 11B, and the third spectral reference light 11C. The phase difference is given.

The optical interference fringe measuring device according to the fourth embodiment is
With the above configuration, the reference light splitter 22
A, 22B, the second total reflection mirror 22C, and the optical path length mirrors 23A to 23C are interposed to simultaneously generate a plurality of systems of spectral reference beams 11A to 11C having different phases, and these spectral reference beams 11A to 11C are measured. The light will be interfered by the spectroscopic measurement lights 9A to 9C formed of the light reflected from the surface 4. These pieces of interference fringe information are simultaneously captured by a plurality of photoelectric conversion cameras, stored in the storage device 20, and compared with the plurality of pieces of interference fringe image information to determine the measurement target surface 4.
Since the shape of the surface is analyzed, the same operation and effect as those of the first and second embodiments can be expected even with the configuration of the fourth embodiment.

[0027]

As is apparent from the above description, according to the present invention, the light from the light source is changed by the beam splitter.
A plurality of spectroscopic measurement lights, which are light reflected from the surface to be measured, and a plurality of spectroscopic reference lights having different phases are simultaneously divided, and a plurality of optics are used for the respective spectroscopic reference lights combined with the respective spectroscopic measurement lights. Since each optical interference system is provided with a photoelectric conversion unit that composes the interference system and captures the interference fringe optical information of these optical interference systems, there is no mechanical movable part that requires precision processing, and the arbitrary phases can be made different at the same time. Since a plurality of pieces of optical interference fringe image information can be obtained at the same time, the shape of a high-speed moving object can be analyzed, and an optical interference fringe measuring apparatus that is less affected by environmental changes can be achieved. Further, as described in claims 2 to 5, a plurality of optical interference fringes having different phases only by incorporating a refraction medium, a thickness medium, a liquid crystal phase shift plate, and a plurality of optical path length mirrors into a plurality of spectral reference lights. Information can be obtained easily.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an optical system of an optical interference fringe measuring device according to a first embodiment of the present invention.

FIG. 2 is a conceptual diagram of an optical system of an optical interference fringe measuring device according to a second embodiment of the present invention.

FIG. 3 is a conceptual diagram of an optical system of an optical interference fringe measurement device according to a third embodiment of the present invention.

FIG. 4 is a conceptual diagram of an optical system of an optical interference fringe measuring device according to a fourth embodiment of the present invention.

FIG. 5 is a conceptual diagram of a conventional optical system.

[Explanation of symbols]

 Reference Signs List 1 light source 2 lens 3 beam splitter 5 measuring light reflecting mirror 6, 7 measuring light splitter 8 first total reflection mirror 9A, 9B, 9C spectral measuring light 10 inverting optical lens 11A, 11B, 11C spectral reference light 12, 13, 22A, 22B Reference light splitter 14, 16 Refraction medium 14A, 16A Liquid crystal phase shift plate 14B, 16B Optical wedge 15, 22C Second total reflection mirror 17A, 17B, 17C Interference unit splitter 18A, 18B, 18C Imaging lens 19A, 19B, 19C Photoelectric conversion camera 20 Storage processing device 23A, 23B, 23C Optical path length mirror

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Seiwa Okamoto Mitutoyo Co., Ltd. 430, Kamiyokoba, Tsukuba, Ibaraki Pref.

Claims (5)

[Claims] A beam splitter simultaneously splits light from a light source into a plurality of spectral measurement lights, which are reflected lights from a surface to be measured, and a plurality of spectral reference lights, each having a different phase. A plurality of optical interference systems are configured by the respective spectral reference lights combined with the measurement light, and each optical interference system is provided with a photoelectric conversion unit for capturing interference fringe optical information of these optical interference systems. Fringe measuring device. 2. A beam splitter for splitting parallel light from a light source into a projection light onto a surface to be measured and reference light, and a plurality of measurements for decomposing the projection light reflected from the surface to be measured into a plurality of spectral measurement lights. An optical splitter, a reference light splitter that decomposes the reference light into a plurality of spectral reference lights, and an optic that is interposed in at least one of the spectral reference lights and generates reference light having a phase different from a phase of another spectral reference light An optical medium that is interposed in at least one of the medium or the spectroscopic measurement light and generates measurement light having a phase different from the phase of the other spectroscopic measurement light, and a plurality of optics combining the spectroscopic measurement light with the spectral reference light. An optical interference fringe measuring apparatus comprising: a plurality of interference unit splitters constituting an interference system; and means for capturing and storing interference fringe optical information of the optical interference system. 3. A beam splitter for splitting parallel light from a light source into a projection light to a surface to be measured and reference light, and a plurality of measurements for decomposing the projection light reflected from the surface to be measured into a plurality of spectral measurement lights. An optical splitter, a reference light splitter that decomposes the reference light into a plurality of spectral reference lights, and a liquid crystal that is interposed in at least one of the spectral reference lights and generates reference light having a phase different from the phase of another spectral reference light A phase shift plate or a liquid crystal phase shift plate that is interposed in at least one of the spectral measurement lights and generates measurement light having a phase different from the phase of another spectral measurement light, and combines the spectral reference light with each of the spectral measurement lights. An optical interference fringe measuring apparatus, comprising: a plurality of interference unit splitters constituting a plurality of optical interference systems, and means for capturing and storing interference fringe optical information of these optical interference systems. Place. 4. A beam splitter for splitting parallel light from a light source into a projection light onto a measured surface and reference light, and a plurality of measurements for decomposing the projected light reflected from the measured surface into a plurality of spectral measurement lights. An optical splitter, a reference light splitter that decomposes the reference light into a plurality of spectral reference lights, and an optic that is interposed in at least one of the spectral reference lights and generates reference light having a phase different from a phase of another spectral reference light A wedge or an optical wedge that is interposed in at least one of the spectroscopic measurement lights to generate measurement light having a phase different from the phase of another spectroscopic measurement light; An optical interference fringe measuring apparatus comprising: a plurality of interference unit splitters constituting an interference system; and means for capturing and storing interference fringe optical information of the optical interference system. 5. A beam splitter for splitting parallel light from a light source into a projection light onto a surface to be measured and reference light, and a plurality of measurements for decomposing the projection light reflected from the surface to be measured into a plurality of spectral measurement lights. An optical splitter, a reference light splitter that decomposes the reference light into a plurality of spectral reference lights, and a light path length that is interposed in at least one of the spectral reference lights and has a different optical path length from that of the other spectral reference lights. At least one set of a reference light splitter and a light path length mirror, which is a spectral reference light having a different phase, is interposed in at least one of the spectral measurement lights, and has a different optical path length from that of the other spectral measurement lights. At least one set of a measurement light splitter and an optical path length mirror, which are phase spectral measurement lights, and a plurality of optical interference systems configured by combining the spectral reference lights with the respective spectral measurement lights. An optical interference fringe measuring apparatus comprising: an interference unit splitter; and means for capturing and storing interference fringe optical information of these optical interference systems.