CN215177523U - Annular light source Fizeau interferometer - Google Patents
Annular light source Fizeau interferometer Download PDFInfo
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- CN215177523U CN215177523U CN202120760366.4U CN202120760366U CN215177523U CN 215177523 U CN215177523 U CN 215177523U CN 202120760366 U CN202120760366 U CN 202120760366U CN 215177523 U CN215177523 U CN 215177523U
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Abstract
The invention provides a fizeau interferometer with an annular light source, which comprises: the device comprises an annular light source generating device, a laser scattering plate, a driving mechanism, a beam splitting mechanism, a collimating lens, a reference lens, a testing lens, an imaging lens and a CCD (charge coupled device) which are sequentially arranged along a first light path direction. The first light path direction and the second light path direction are perpendicular to each other. The center of the laser scattering plate is superposed with the optical axis and used for scattering annular light, and the driving mechanism is used for driving the laser scattering plate to rotate. The laser scattering plate is added at the annular light source, and the driving devices such as the motor and the like are used for driving the laser scattering plate to rotate, so that noise points in an interference field are eliminated, the illumination of the interference field becomes more uniform, interference fringes become clearer, and good fringe contrast can still be kept, so that the measurement requirement is met.
Description
Technical Field
The utility model belongs to optics interfere the detection field, a annular light source fizeau interferometer is related to.
Background
When the surface shape of an optical element is detected using a high-precision laser interferometer, both the internal optical system of the interferometer and the surface of the element to be detected have minute defects and microscopic defects. These microscopic defects and imperfections tend to produce non-imaging light and cause stray light and coherent superposition. Therefore, coherent noises such as a plurality of Newton rings or bulls-eyes are generated in the interferogram, and the coherent noises affect the spatial structure of the interferogram, so that the quality of the interferogram is reduced, and the measurement result and the accuracy are affected.
The annular light source technology is based on an off-axis illumination principle, compared with a point light source illumination mode in a laser interferometer, when emergent light passes through an optical element, extra parasitic fringes can be generated due to microscopic defects on the surface of the optical element, and the interferometer in the annular light source illumination mode only interferes an optical cavity, so that the influence caused by the surface defects of the optical element is inhibited.
It can be seen that the ring light source technology can better suppress coherent noise, but still has the following disadvantages: each off-axis point light source and on-axis point light source which form the annular light source illuminate differently, the off-axis point light source radiates spherical waves in a non-common sense, the whole annular light source radiates conical surface waves, hollow light beams generated by the conical surface waves are the result of the dual functions of typical geometric optics and light diffraction, therefore, light rays emitted by each off-axis point light source are coherently superposed on an axis to form a bright spot with extremely strong radiation intensity, the contrast and the illumination uniformity of surrounding interference fringes are greatly influenced, and the measurement is seriously influenced. Fig. 1 shows the background light intensity obtained under illumination of an annular light source, and the contrast of interference fringes is seriously affected by the existing noise points, so that the measurement requirement cannot be met.
Disclosure of Invention
In order to solve the above problem, an annular light source fizeau interferometer capable of eliminating interference field noise points is provided, the utility model adopts the following technical scheme:
the utility model provides an annular light source fizeau interferometer, a serial communication port, include: the device comprises an annular light source generating device, a laser scattering plate, a driving mechanism, a beam splitting mechanism, a collimating lens, a reference lens, a testing lens, an imaging lens and a CCD (charge coupled device) which are sequentially arranged along a first light path direction. The annular light source generating device is used for forming annular light, the center of the laser scattering plate is overlapped with an optical axis and used for scattering the annular light, the driving mechanism is used for driving the laser scattering plate to rotate around the optical axis, the beam splitting mechanism is at least used for dividing light emitted by the laser scattering plate into scattered light along a first light path direction, the collimating lens is used for converting the scattered light into collimating lens parallel light, the reference lens has wedge degree and is used for reflecting the collimating lens parallel light to form reference light, the testing lens is used for reflecting the collimating lens parallel light penetrating through the reference lens to form testing light, the imaging lens and the CCD are sequentially arranged in a second light path direction formed by the beam splitting mechanism reflecting the reference light and the testing light, and the reference light and the testing light after being split by the beam splitting mechanism are imaged on the CCD to form interference fringes. The first light path direction and the second light path direction are perpendicular to each other.
The utility model provides an annular light source fizeau interferometer can also have such characteristic, and wherein, annular light source generates the device and includes the laser instrument, the beam expanding mechanism, annular lens and two telecentric mirror heads that arrange in proper order along first light path direction, and wherein, beam expanding mechanism is used for becoming the beam expanding parallel light with the light beam of laser instrument outgoing, and annular lens and two telecentric mirror heads cooperate and are used for becoming the beam expanding parallel light into annular light.
The utility model provides an annular light source fizeau interferometer can also have such characteristic, and wherein, the beam diameter scope of laser instrument outgoing is 0.5mm ~ 2 mm.
The utility model provides an annular light source fizeau interferometer can also have such characteristic, and wherein, the magnification of expanding the beam mechanism sets up to 5 times ~ 20 times.
The utility model provides an annular light source fizeau interferometer can also have such characteristic, and wherein, actuating mechanism is the motor.
The utility model provides an annular light source fizeau interferometer can also have such characteristic, and wherein, motor speed sets up to 60r/min ~ 3200 r/min.
The utility model provides an annular light source fizeau interferometer can also have such characteristic, and wherein, the bore scope of the reference mirror that has the wedge degree is 10mm ~ 200 mm.
Action and Effect of the invention
According to the utility model discloses an annular light source fizeau interferometer adds rotatory laser scattering board in annular light source fizeau interferometer to eliminate interference field noise point, annular light source in the interferometer generates the department promptly, adds a slice laser scattering board, makes laser scattering board rotatory through drive arrangement such as motor, makes the illumination of interference field become more even, and the interference fringe becomes more clear, and still can keep good fringe contrast, thereby reaches the measurement requirement. Meanwhile, the structure is simple and easy to realize.
Drawings
FIG. 1 is a background light intensity diagram obtained under illumination of an annular light source according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a Fizeau interferometer with a ring light source using a rotating laser diffuser in an embodiment of the invention;
fig. 3 is a background light intensity diagram obtained by a fizeau interferometer, which is an annular light source using a rotating laser scattering plate according to an embodiment of the present invention;
fig. 4 is an interference fringe pattern obtained by a ring light source fizeau interferometer using a rotating laser diffuser in an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made with reference to the accompanying drawings and examples.
< example >
Fig. 2 is a schematic structural diagram of a ring light source fizeau interferometer using a rotating laser scattering plate according to an embodiment of the present invention.
As shown in fig. 2, the ring light source fizeau interferometer 100 includes a light source generating device 1, a laser scattering plate 2, a driving mechanism (not shown), a beam splitting mechanism 3, a collimating lens 4, a reference mirror 5 with a wedge, a testing mirror 6, an imaging lens 7 and a CCD8, which are sequentially arranged along a first light path direction.
The first light path direction is perpendicular to the second light path direction.
The light source generating device 1 includes a laser 11, a beam expanding mechanism 12, an annular lens 13, and a double telecentric lens 14, which are sequentially arranged along a first optical path direction.
The laser 11 is used as a light source for emitting a light beam, and in the present embodiment, the operating wavelength λ of the laser is 0.6328 μm, the diameter of the light beam of the light source is 2mm, and the length d of the interference cavity is 100 mm.
The beam expanding mechanism 12 has a first lens 121 close to the laser 11 and a second lens 122 of the laser, the first lens 121 is a negative lens, and the second lens 122 is a positive lens, and is used for changing the light beam emitted by the laser into expanded parallel light. In this embodiment, the amplification factor of the beam expanding mechanism is 5 times, and the diameter of the beam expanding parallel light is 10 mm.
The annular lens 13 has a transparent portion and an opaque portion for converting the parallel light to generate the first annular light. In this embodiment, the annular lens may be selected to have a thickness of 2mm, a diameter of the opaque portion of 2mm, an outer diameter of the transparent portion of 10mm, and a diameter of the cross-sectional lens of 4 mm.
The double telecentric lens 14 is configured to convert the first annular light into a second annular light serving as an annular light source, and has an object-side lens assembly 141 and an image-side lens assembly 142.
The laser diffusion plate 2 is centered on the optical axis for diffusing the ring light.
And a driving mechanism (not shown in the figure) for driving the laser scattering plate to rotate around the optical axis, wherein the driving mechanism can be a motor, and the motor speed is set to be 200r/min in the embodiment.
The beam splitting mechanism 3 is used for at least splitting the light emitted from the laser scattering plate into scattered light along the first optical path direction.
The collimator lens 4 is used to change the scattered light into collimator lens parallel light.
The reference mirror 5 has a wedge degree, and is used for reflecting the collimated light of the collimator lens to form reference light, and the aperture of the reference mirror is set to be 20mm in the embodiment.
The test mirror 6 is used for reflecting the collimated lens parallel light passing through the reference mirror to form test light.
The imaging lens 7 and the CCD8 are sequentially arranged in a second light path direction formed by reflecting the reference light and the test light by the beam splitting mechanism 3, and the reference light and the test light split by the beam splitting mechanism 3 are imaged on the CCD8 to form interference fringes.
The light beam emitted by the laser is firstly changed into expanded parallel light with larger diameter size by the beam expanding mechanism 12, and the expanded parallel light forms annular light after passing through the annular lens 13 and the double telecentric lens 14. The annular light is divided into scattered light along the first light path direction after passing through the beam splitting mechanism after passing through the light emitted from the laser scattering plate 2 rotating at a constant speed. The scattered light is changed into collimating lens parallel light after passing through the collimating mirror 4, and is incident to an interference cavity formed between the reference mirror 5 and the test mirror 6. Parallel light enters a collimating lens of the interference cavity, one part of the parallel light reaches a reference surface of a standard reference mirror 5 with wedge degree and is reflected back as reference light, the other part of the parallel light passes through the reference mirror and is reflected back as test light after passing through a test mirror 6, and the reference light and the test light after being split by the beam splitting mechanism 3 are imaged on a CCD8 to form interference fringes.
Fig. 3 and 4 are a background light intensity diagram and an interference fringe diagram obtained by a ring light source fizeau interferometer using a rotating laser scattering plate according to an embodiment of the present invention.
As shown in fig. 3 and 4, the laser emitting diameter is selected to be 2 mm; the beam expanding mechanism is 5 times; the aperture of the reference mirror is 20 mm; when the motor speed is 200r/min, no obvious noise point exists in the background light intensity, and the contrast of the interference fringes is not obviously attenuated.
Examples effects and effects
According to the annular light source Fizeau interferometer provided by the embodiment, the laser scattering plate is added at the annular light source, and the laser scattering plate is rotated through the driving devices such as the motor, so that noise points in an interference field are eliminated, the illumination of the interference field becomes more uniform, interference fringes become clearer, and good fringe contrast can still be maintained, so that the measurement requirement is met. Meanwhile, the structure is simple and easy to realize.
The annular light source fizeau interferometer that this embodiment provided, the annular lens size in its annular light source generation device is great, and the external diameter is 10mm, and the internal diameter is 2mm, and is lower to the machining precision requirement for the processing degree of difficulty reduces, the production and processing of being convenient for.
In the fizeau interferometer with the annular light source provided by this embodiment, the diameter range of the light beam emitted by the laser is 0.5 mm-2 mm, which is the aperture of the commonly used laser.
In the annular light source fizeau interferometer provided by this embodiment, the amplification factor of the beam expanding system can be selected from 5 times to 20 times, and is determined by the aperture of the laser and the aperture of the reference mirror. That is, when a laser with a caliber of 2mm and a reference mirror with a caliber of 19.5mm are adopted, the magnification of the beam expanding system can be correspondingly adopted by 10 times.
In the annular light source fizeau interferometer provided by the embodiment, the motor speed is set to be 60 r/min-3200 r/min. When the motor speed is less than 60r/min, the image speckles are serious, the stripe contrast is poor, and when the motor speed is greater than 3200r/min, the stripe contrast is also poor, so that when the motor speed is less than 60r/min or greater than 3200r/min, the measurement requirement cannot be met.
The aperture range of the reference mirror with the wedge degree of the annular light source fizeau interferometer provided by the embodiment is 10 mm-200 mm, which is the aperture of the common reference mirror.
The above-described embodiments are merely illustrative of specific embodiments of the present invention, and the present invention is not limited to the description of the above-described embodiments.
Claims (7)
1. An annular light source fizeau interferometer, comprising:
an annular light source generating device, a laser scattering plate, a driving mechanism, a beam splitting mechanism, a collimating lens, a reference lens, a testing lens, an imaging lens and a CCD which are sequentially arranged along a first light path direction,
wherein the annular light source generating device is used for generating annular light,
the center of the laser scattering plate is superposed with the optical axis and is used for scattering the annular light,
the driving mechanism is used for driving the laser scattering plate to rotate around the optical axis,
the beam splitting mechanism is at least used for splitting the light emitted by the laser scattering plate into scattered light along the first light path direction,
the collimating lens is used for converting the scattered light into collimating lens parallel light,
the reference mirror has wedge degree and is used for reflecting the parallel light of the collimating lens to form reference light,
the test mirror is used for reflecting the parallel light of the collimating lens passing through the reference mirror to form test light,
the imaging lens and the CCD are sequentially arranged in the second light path direction formed by the beam splitting mechanism reflecting the reference light and the test light, the reference light and the test light after being split by the beam splitting mechanism are imaged on the CCD to form interference fringes,
the first light path direction and the second light path direction are perpendicular to each other.
2. The annular light source fizeau interferometer of claim 1, wherein:
the annular light source generating device comprises a laser, a beam expanding mechanism, an annular lens and a double telecentric lens which are sequentially arranged along the first light path direction,
wherein the beam expanding mechanism is used for changing the light beam emitted by the laser into expanded parallel light,
the annular lens and the double telecentric lens are matched with each other to convert the beam expanding parallel light into the annular light.
3. The annular light source fizeau interferometer of claim 2, wherein:
wherein the diameter range of the light beam emitted by the laser is 0.5 mm-2 mm.
4. The annular light source fizeau interferometer of claim 2, wherein:
wherein, the magnification of the beam expanding mechanism is set to be 5-20 times.
5. The annular light source fizeau interferometer of claim 1, wherein:
wherein the driving mechanism is a motor.
6. The annular light source fizeau interferometer of claim 5, wherein:
wherein the speed of the motor is set to be 60 r/min-3200 r/min.
7. The annular light source fizeau interferometer of claim 1, wherein:
wherein the aperture range of the reference mirror is 10 mm-200 mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202120760366.4U CN215177523U (en) | 2021-04-14 | 2021-04-14 | Annular light source Fizeau interferometer |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202120760366.4U CN215177523U (en) | 2021-04-14 | 2021-04-14 | Annular light source Fizeau interferometer |
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| CN215177523U true CN215177523U (en) | 2021-12-14 |
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| CN202120760366.4U Active CN215177523U (en) | 2021-04-14 | 2021-04-14 | Annular light source Fizeau interferometer |
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