Spatial phase shifting interferometer using multi wavelength
View Patent ↗Provided is a spatial phase shifting interferometer using a multi wavelength. More particularly, provided is a spatial phase shifting interferometer using a multi wavelength capable of more rapidly measuring a precise shape of a measurement object by simultaneously oscillating laser having different wavelengths and passing the oscillated laser through a beam splitter and a lens to analyze an interference fringe of the measurement object.
1. A spatial phase shifting interferometer using a multi wavelength, comprising:
a laser oscillator that oscillates a plurality of lasers having different wavelengths;
a first beam splitter that transmits and reflects the lasers emitted from the laser oscillator and transmitting a lens;
a Mirau lens unit that measures a measurement object by the lasers reflected from the first beam splitter;
a wavelength demultiplexer that transmits the lasers reflected from the Mirau lens unit through the first beam splitter, the lasers transmitted from the first beam splitter through a quarter wave plate, and demultiplexes the lasers transmitting the quarter wave plate into more than two kinds of wavelengths;
pixelated CCD camera whose number is correspondence to number of kinds of wavelength units that transmit the wavelengths demultiplexed by the wavelength demultiplexer through a pixelated polarizer to indicate an interference fringe; and
a PC unit that uses the interference fringe in the pixelated CCD camera unit to analyze a precise shape.
2. The spatial phase shifting interferometer using a multi wavelength of claim 1 , wherein the laser oscillator includes a mode mixer that makes a coherence of the oscillated lasers wavelengths short.
3. The spatial phase shifting interferometer using a multi wavelength of claim 1 , wherein the first beam splitter includes a linear polarizer.
4. The spatial phase shifting interferometer using a multi wavelength of claim 1 , wherein the lasers having different wavelengths are collected as one by an optical fiber coupler and are then incident to a multi-mode optical fiber and the coherence of the wavelength of the lasers incident to the multi-mode optical fiber is short by using a vibrator.
5. The spatial phase shifting interferometer using a multi wavelength of claim 4 , wherein the vibrator is a speaker or a piezoelectric element.
6. The spatial phase shifting using a multi wavelength of claim 1 , wherein the Mirau lens unit includes an objective lens, a reference mirror disposed under the objective lens, a second beam splitter disposed under the reference mirror, and a quarter wave plate disposed under the second beam splitter and the lasers reflected from the first beam splitter are incident through the objective lens and transmit through the second beam splitter and are reflected therefrom, and
the quarter wave plate disposed under the second beam splitter is configured so that a polarization of the laser reflected from the measurement object after transmitting the second beam splitter is vertical to a polarization of the laser reflected from the reference mirror.
7. The spatial phase shifting interferometer using a multi wavelength of claim 1 , wherein the Mirau lens unit includes an objective lens, a reference mirror disposed under the objective lens, a second beam splitter disposed under the reference mirror, and a quarter wave plate disposed above the second beam splitter and the lasers reflected from the first beam splitter are incident through the objective lens and transmit through the second beam splitter and are reflected therefrom, and
the quarter wave plate disposed above the second beam splitter is configured so that a polarization of the laser reflected from the measurement object after transmitting the second beam splitter is vertical to a polarization of the laser reflected from the reference mirror.
8. The spatial phase shifting interferometer using a multi wavelength of claim 1 , wherein the wavelength demultiplexer is a dichroic beam splitter or a color band pass filter.
9. A spatial phase shifting interferometer using a multi wavelength, comprising:
a laser oscillator that oscillates a plurality of lasers having different wavelengths;
a polarizing beam splitter that transmits and reflects the lasers emitted from the laser oscillator and transmitting a lens;
a microscope interferometer unit in which the lasers reflected from the polarizing beam splitter are incident to an measurement object, the lasers transmitting the polarizing beam splitter are incident to a reference mirror, and the polarizing beam splitter re-transmits and re-reflects the lasers reflected from the measurement object and the lasers reflected from the reference mirror;
a wavelength demultiplexer which transmits the lasers re-transmitting the polarizing beam splitter and reflected therefrom through the quarter wave plate and splits the lasers transmitting the quarter wave plate into more than two kinds of wavelengths;
pixelated CCD camera whose number is correspondence to number of kinds of wavelength units that transmit the wavelengths demultiplexed by the wavelength demultiplexer through a pixelated polarizer to indicate an interference fringe; and
a PC unit that uses the interference fringe in the pixelated CCD camera unit to analyze a precise shape.
10. The spatial phase shifting interferometer using a multi wavelength of claim 9 , wherein the laser oscillator includes a mode mixer that makes a coherence of the oscillated laser wavelengths short.
11. The spatial phase shifting interferometer using a multi wavelength of claim 9 , wherein the polarizing beam splitter includes a linear polarizer.
12. The spatial phase shifting interferometer using a multi wavelength of claim 9 , wherein the lasers having different wavelengths are collected as one by an optical fiber coupler and are then incident to a multi-mode optical fiber and the coherence of the wavelengths of the lasers incident to the multi-mode optical fiber is short by using a vibrator.
13. The spatial phase shifting interferometer using a multi wavelength of claim 12 , wherein the vibrator is a speaker or a piezoelectric element.
14. The spatial phase shifting interferometer using a multi wavelength of claim 9 , wherein the microscope interferometer unit includes a quarter wave plate so that a polarization of the lasers reflected from the measurement object is vertical to a polarization of the lasers reflected from the reference mirror and the lasers reflected from the polarizing beam splitter and transmitting the polarizing beam splitter transmit the quarter wave plate.
15. The spatial phase shifting interferometer using a multi wavelength of claim 9 , wherein the polarizing beam splitter re-transmits and re-reflects the lasers reflected from the measurement object and the lasers reflected from the reference mirror and a part of the re-transmitted and re-reflected lasers transmits an objective lens and the quarter wave plate and is incident to the wavelength demultiplexer.
16. The spatial phase shifting interferometer using a multi wavelength of claim 9 , wherein the wavelength demultiplexer is a dichroic beam splitter or a color band pass filter.