TW201305530A - Measurement method of small angle and small displacement and the device thereof - Google Patents

Abstract

This invention relates to a measurement method of small angle and small displacement and its device. The device comprises a light source, a beam splitter, a displacement detector, an optical lens, a prism, an analyzer, a light detector, an amplifier, a filter, a phase-locked amplifier, and a computer. The method comprises: placing the object under test on the optical lens; projecting heterodyne light source to the beam splitter to generate transmission optical energy directed to the displacement detector then to the object under test; reflecting the transmission light by the optical lens, followed by the displacement detector, the beam splitter, the prism, the analyzer, the light detector, the amplifier, the filter, and the phase-locked amplifier, so as to obtain a first test signal of the light phase difference between two boundaries of the object under test; then rotating the optical lens by a small angle to obtain a second test signal of the light phase difference between two boundaries of the object under test; using the phase-locked amplifier to detect the electrical signal of the phase variation; and then using the computer to compute precisely the rotation angle, displacement, gap and height difference of the object under test.

Description

Small angle and small displacement measuring method and device thereof

The invention provides a measuring method and device for small angle and small displacement, in particular to an optical device which combines the common optical path heterodyne and the surface plasma resonance and the interface total reflection, which uses the heterodyne light source to enter the single Having at least one plating layer, at least one interface total reflection and at least one recessive total reflection are generated, and the transmitted light obtains the first and second test signals of the phase difference between the two boundaries of the object to be tested, and can be accurately calculated by the computer to be tested. The rotation angle, the displacement amount, the gap and the height difference of the object; the invention can be applied to the measurement of objects, specimens, etc. in precision manufacturing, stress, strain, biochemistry, biomedicine and the like.

According to the prior art, a small angle and small displacement measuring device and method thereof are provided: the small angle and small displacement measuring device comprises: a light source 10 capable of emitting a linearly polarized light source; and a beam splitter 11 The light source can generate the reflected light 111 and the transmitted light 112; a stack 12, on which the object to be tested 20 is placed, and the 稜鏡12 transmits the transmitted light fold 112 into the right angle 稜鏡12, passing the right angle to the oblique side After performing a recession reflection, it is directed to the other right angle side; the second depolarization plates 13 and 14 are disposed, the first depolarization plate 13 is supplied with the transmitted light 112 of the crucible 12, and the second depolarization plate 14 is reflected by the dichroic mirror 11. The light 111 is incident on the second light detectors 15, 16 , and the first and second optical detectors 15 and 16 respectively transmit the transmitted light 112 and the reflected light 111 of the first and second depolarization plates 13 and 14 into and into a first reference telecommunications and a first test telecommunications and a second reference telecommunications and a second test telecommunications generated after the rotation of the chirp 12; a lock-in amplifier 17 capable of detecting a telecommunication difference between the first and second test signals; and a computer 18 , can calculate the phase change of the first and second test signals, and obtain the rotation angle and direction.

The measurement method of the small angle and the small displacement is:

1. The object to be tested 20 is placed on the crucible, and the object to be tested 20 and the crucible 12 can rotate synchronously;

Second, the light source 10 will be directed to the beam splitter 11 to form the reflected light 111 and the transmitted light 112, the transmitted light 112 can be directed to the object to be tested 20;

3. Obtaining a first reference signal, the reflected light 111 first passes through the first depolarization plate 13 and then enters the first photodetector 15 to obtain a first reference signal;

4. Obtaining the first test signal, the transmitted light 112 is first injected perpendicularly into the crucible 12, and after a full reflection of the recession, is directed to the other right angle side of the crucible 12, and then reflected to the second depolarization plate 14 and enters the second light. a detector 16 for obtaining a first test signal of a phase difference between two boundaries of the object to be tested;

5. Focusing to obtain the second reference signal and the second test signal, and rotating the 稜鏡12 by a small angle, according to the third and fourth steps to obtain a second test signal of the phase difference between the second reference signal and the object 20;

6. Detecting the phase difference, and converting the first and second reference signals and the test signal into electrical signals by the first and second photodetectors 15 and 16, and then detecting the phase change amount by the lock-in amplifier 17 ;

7. Calculate the displacement and the rotation angle, and the lock-in amplifier 17 detects the electrical signal measured by the phase change amount, and calculates the rotation angle and direction of the 稜鏡12 by computer operation, and learns the object to be tested 20 Rotation angle, displacement, clearance, and height difference.

In the foregoing, a total reflection of the recession is adopted, so that the first and second test signals of the two-edge optical phase difference of the object to be tested are not sufficiently obvious, and thus the resolution of the electrical signal is affected.

In view of the above-mentioned lack of timing, the inventor has been engaged in research and many practical experiences for many years, and has been researched and designed by many parties. In the present invention, a small angle and small displacement measurement method and apparatus are proposed as The foregoing expectation is an implementation and basis.

The main object of the present invention is to provide a new method and device for measuring small angles and small displacements of an optical path. The device comprises a light source, a beam splitter, a displacement detector, an optical lens, a cymbal, a depolarization plate, a photodetector, an amplifier, a filter, a lock-in amplifier, and a computer; The method is to place the object to be tested on the optical lens, and use the heterodyne light source to shoot the beam splitter to generate transmitted light energy to pass through the displacement detector, and then to the object to be tested, the transmitted light is reflected by the optical lens, and the displacement detector and the beam splitter are separated. Mirror, 稜鏡, depolarization plate, photodetector, amplifier, filter, lock-in amplifier, to obtain the first test signal of the optical phase difference between the two edges of the object to be tested, and then the optical lens rotates a small angle to obtain the object to be tested The second test signal of the two-phase optical phase difference detects the electrical signal measured by the phase-locked amplifier by the phase change, and the computer can accurately calculate the rotation angle, the displacement amount, the gap and the height difference of the object to be tested. .

One of the primary objects of the present invention is to provide a method and apparatus for measuring a small angle and a small displacement which can produce a distinct phase difference between two boundaries of an object to be tested. The system has at least one plating layer on the other right angle side, and can perform at least one total reflection and at least one surface plasma resonance or decay total reflection, so that the light wave of the reflected light and the transmitted light is increased, and the signal of the phase difference is deepened.

The theoretical basis applied by the present invention includes three:

1. Total reflection TIR: Total reflection is an optical phenomenon. When light passes through two mediums with different refractive indices, part of the light will be refracted at the interface of the medium, and the rest will be reflected. However, when the incident angle is larger than the critical angle When large, the light will stop entering the other interface, and vice versa will all reflect toward the inner surface.

Second, surface plasma resonance SPR: surface plasma resonance sensor kretschmann configuration, when the incident angle α is equivalent to the resonance angle αsp, that is, the surface plasma waves are excited on the reflective surface of the crucible.

3. Displacement detection: The composition includes a microscope with a focal length f and an optical lens placed on the focal plane. The heterodyne light source is injected into the microscope objective and then reflected to the optical lens for reflection, and then returned to the microscope, if the mirror When fixed on the focal plane, the incident and reflected light will be parallel, otherwise the reflected light and the incident light will have a bias angle.

The present invention is a small angle and small displacement measuring method and device thereof. Please refer to the second drawing, which is a schematic diagram of the device of the present invention. The figure discloses a small angle and small displacement measuring device, which comprises: a light source 3, a beam splitter 4, a displacement detector 41, an optical lens 42, a cymbal 43, a depolarization plate 44, a photodetector 45, an amplifier 46, a filter 47, a phase lock Amplifier 48, and a computer 49. Wherein, the light source 3 can emit a linearly polarized light source, especially a heterodyne light source; the beam splitter 4 can generate the reflected light 31 and the transmitted light 32 by the light source 3; a displacement detector 41 can pass the transmitted light 32 of the beam splitter 4; The object to be tested 5 is disposed on the lens 42 for the transmitted light 32 of the displacement detector 41 to be returned to the beam splitter 4, which is the first and second test signal generating portions of the two-border optical phase difference of the object to be tested 20; The retroreflected transmitted light 32 is refracted into the right angle 稜鏡43, and is totally totally reflected by the right angle and then directed to the other right angle side; the depolarization plate 44 is used to transmit the transmitted light 32 of the 稜鏡43; the photodetector 45 is used for the depolarization The transmitted light 32 of the board 44 is incident and converted into telecommunication; the amplifier 46 amplifies the telecommunication of the photodetector 45; the filter 47 trims the telecommunication of the amplifier 46; the lock-in amplifier 48 can detect the telecommunication difference of the test signal; 49 can calculate the phase change of the first and second test signals, and obtain the angle and direction of the optical lens mirror 42, and then know the rotation angle, the displacement amount, the gap and the height difference of the object to be tested 20.

The 稜鏡43 is a common light circuit, and the other right angle side has at least one plating layer 431 [such as titanium film (or chrome film...) 2 nm, gold film (or silver film...) 45.5 nm, etc., wherein the gold film is relatively easy to adhere. Another titanium film or chrome film] can perform one total reflection and one surface plasma resonance, and the crucible 43 can be a long stripe (not shown) having a slope, and the strip shape is At least one mask is plated. Moreover, the other end of the optical lens 42 is a piezoelectric transducer 6, and the position of the optical lens 42 is controlled by the stepless extension, so that the displacement detector 41 can be in focus with the object to be tested. The displacement detector 41 is a microscope.

The method for measuring small angle and small displacement according to the present invention:

1. The object to be tested 5 is placed on the optical lens 42;

2, the light source 3 will be directed to the beam splitter 4, forming a reflected light 31 and transmitted light 32, the transmitted light 32 can be transmitted through the displacement detector 41, and then directed to the object to be tested 5;

3. The first test signal is obtained, and the transmitted light 32 is reflected by the optical lens 42 through the displacement detector 41, the beam splitter 4, the 稜鏡43, the depolarization plate 44, the photodetector 45, the amplifier 46, the filter 47, Locking the amplifier 48 to obtain the first test signal of the phase difference between the two boundaries of the object to be tested 5;

4. The second reference signal and the second test signal are obtained by focusing, and the optical lens 42 is rotated by a small angle, and according to the third step, the second test signal of the optical phase difference between the two boundaries of the object to be tested 5 is obtained;

5. Calculate the displacement and the rotation angle, and the lock-in amplifier 48 detects the electrical signal measured by the change of the phase thereof, and calculates the rotation angle and direction of the optical lens 42 by the computer 49, thereby learning the object to be tested 5 The angle of rotation, the amount of displacement and the height difference.

The foregoing method consists in using the first and second test signals of the transmitted light 32 having a phase difference between the two boundaries of the object 5 to be tested, and the 稜鏡43 has a plating layer 431 at the corner, so that the light source is generated at least once in its internal structure. The total reflection of the interface and at least one decay total reflection, so that the light wave of the reflected light and the transmitted light is increased, and the signal of the phase difference is deepened.

The above is a detailed description and drawings of the preferred embodiments of the invention, and is not intended to limit the invention. The scope of the invention is to be determined by the scope of the following patents, and the embodiments and similar structures of the spirit of the patent scope and the similar variations are intended to be included in the invention.

[知知]

10. . . light source

11. . . Beam splitter

111. . . reflected light

112. . . Transmitted light

12. . .稜鏡

13. . . First solution plate

14. . . Second solution plate

15. . . First optical detector

16. . . Second optical detector

17. . . Lock-in amplifier

18. . . computer

20. . . Analyte

[this invention]

3. . . light source

31. . . reflected light

32. . . And transmitted light

4. . . Beam splitter

41. . . Displacement detector

42. . . Optical lenses

43. . .稜鏡

44. . . Depolarization plate

45. . . Light detector

46. . . Amplifier

47. . . filter

48. . . Lock-in amplifier

49. . . computer

5. . . Analyte

6. . . Piezoelectric transducer

The first figure is a schematic diagram of a conventional measuring device for small angles and small displacements;

The second figure is a schematic diagram of the measuring device for small angle and small displacement of the present invention.

3. . . light source

31. . . reflected light

32. . . And transmitted light

4. . . Beam splitter

41. . . Displacement detector

42. . . Optical lenses

43. . .稜鏡

44. . . Depolarization plate

45. . . Light detector

46. . . Amplifier

47. . . filter

48. . . Lock-in amplifier

49. . . computer

5. . . Analyte

6. . . Piezoelectric transducer

Claims (7)

A method for measuring small angles and small displacements: first, placing the object to be tested on the optical lens; second, directing the light source toward the beam splitter to form reflected light and transmitted light, and the transmitted light can be transmitted through the displacement detector. And then to the object to be tested; third, obtain the first test signal, the transmitted light is reflected by the optical lens, through the displacement detector, the beam splitter, the 稜鏡, the depolarization plate, the photodetector, the amplifier, the filter, the phase lock An amplifier for obtaining a first test signal of a phase difference between two boundaries of the object to be tested; fourth, focusing to obtain a second reference signal and a second test signal, rotating the optical lens by a small angle, and obtaining the object to be tested according to the third step The second test signal of the phase difference between the two boundary lights; five, calculating the displacement amount and the rotation angle, detecting the electrical signal measured by the phase-locked amplifier of the phase change amount, calculating the rotation angle and direction of the optical lens by computer operation And further, the rotation angle, the displacement amount, the gap, and the height difference of the object to be tested are obtained; the method described above is to use the first and second test signals of the phase difference between the two boundaries of the object to be tested, and the edge Light source produces light can make at least one interface and is totally reflected at least once a decline in its internal total reflection structure. A small angle and small displacement measuring device comprises: a light source capable of emitting a linearly polarized light source; a beam splitter capable of generating reflected light and transmitted light from the light source; and a displacement detector for transmitting by the beam splitter The light passes through; an optical lens is provided with the object to be tested, and the transmitted light of the displacement detector is retroreflected to the beam splitter, which is the first and second test signal generating portions of the two-edge optical phase difference of the object to be tested; For the retroreflected transmitted light to be refracted into a right angle 稜鏡, after a full reflection on the right side of the right angle, and then directed to the other right angle side; a depolarization plate for the transmitted light of the sputum; a photodetector for the solution The transmitted light of the board is incident and converted into telecommunications; an amplifier that amplifies the telecommunication of the photodetector; a filter that trims the telecommunications of the amplifier; and a lock-in amplifier that can measure the difference in telecommunications of the test signal; The computer can calculate the phase change of the first and second test signals to obtain the rotation angle and direction. The small angle and small displacement measuring device according to claim 2, wherein the other right angle side is plated to perform at least one total reflection and at least one surface plasma resonance. The measuring device of small angle and small displacement as described in claim 2, wherein the light source is a heterodyne light source. A small angle and small displacement measuring device as described in claim 2, wherein the other end of the optical lens is a piezoelectric transducer. A small angle and small displacement measuring device as described in claim 2, wherein the displacement detector is a microscope. A small angle and small displacement measuring device as described in claim 2, wherein the crucible is at least one mask plating.