A dual-angle parallel interference system

Abstract

This invention relates to the field of interferometric spectral imaging technology and discloses a dual-angle parallel interferometric system, including a light source unit, a first interferometric unit, a beam splitting unit, a second interferometric unit, and an image acquisition unit. The first and second interferometric units are located at two different orientations of the sample under test. The light source unit projects a light beam onto the beam splitting unit. After reflection and transmission by the beam splitting unit, the light beam forms a first beam and a second beam, respectively. The first beam interferes in the first interferometric unit and projects an interferometric image about a first angle of the sample under test onto the image acquisition unit. The second beam interferes in the second interferometric unit and projects an interferometric image about a second angle of the sample under test onto the image acquisition unit. This system enables simultaneous interferometric imaging of two angles of the sample without changing the object's position, covering twice the angular range of the sample and expanding the application range of the interferometer.

Description

Technical Field

[0001] This invention relates to the field of interferometric spectral imaging technology, and more particularly to a dual-angle parallel interferometric system. Background Technology

[0002] Interferometers have a unique advantage in resolving microscopic features. Based on the principle of light interference, interference fringes are generated. The interference fringes distributed throughout the image contain high information about the surface topography. The light reflected from the surface to be measured and the light reflected from the reference plane will form an optical path difference. Since the wavelength scale of light is on the nanometer scale, the sub-nanometer optical path difference can be resolved by the interference fringes, thus obtaining a high resolution capability of 0.1 nanometers.

[0003] However, when imaging a smooth surface, the interferometer is limited by the numerical aperture of the objective lens, resulting in a small angle of light reflection. For example, an interferometer objective lens with a magnification of 50x and a numerical aperture of 0.55 has a receiving angle of 33.4°. When using a lens with a large field of view and a small numerical aperture, the light reflection angle can be as small as less than 1°. This deficiency greatly limits the application scenarios of interferometers. To solve this problem, existing techniques measure multiple angles by rotating the interferometer or the sample. However, this method introduces micron-level motion errors, which severely reduces the measurement accuracy and significantly prolongs the measurement time. Summary of the Invention

[0004] The present invention aims to provide a dual-angle parallel interferometry system, which can simultaneously perform interferometric imaging of two angles of a sample without changing the position of the object, and covers twice the angle range of the sample without affecting the measurement efficiency, thereby expanding the application range of the interferometer.

[0005] To achieve the above objectives, the basic solution of the present invention is as follows:

[0006] A dual-angle parallel interferometry system includes a light source unit, a first interferometry unit, a beam splitting unit, a second interferometry unit, and an image acquisition unit. The light source unit is used to emit a light beam to the beam splitting unit, and the beam splitting unit is used to split the light beam. The first interferometry unit includes a first sample arm and a first reference arm, and the second interferometry unit includes a second sample arm and a second reference arm.

[0007] The first sample arm and the second sample arm are located at two different positions on the sample to be tested, and are used to acquire the object light from two different angles of the sample to be tested.

[0008] The light source unit projects a light beam onto the beam splitting unit. After reflection and transmission by the beam splitting unit, the light beam forms a first beam and a second beam, respectively. In the first interference unit, the first beam is projected onto the sample under test via the first sample arm. The first beam reflected by the sample under test is projected onto the image acquisition unit via the beam splitting unit. The image acquisition unit acquires a first object beam about the sample under test. The second beam is reflected inside the first reference arm and then projected onto the image acquisition unit via the beam splitting unit. The image acquisition unit acquires a first reference beam and, based on the first reference beam and the first object beam, acquires an interference image of the sample under test from a first viewing angle.

[0009] In the second interference unit, the second beam is projected onto the sample under test via the second sample arm. The second beam reflected by the sample under test is projected onto the image acquisition unit via the beam splitting unit. The image acquisition unit acquires the second object beam about the sample under test. The second beam is reflected inside the second reference arm and then projected onto the image acquisition unit via the beam splitting unit. The image acquisition unit acquires the second reference beam and acquires the second angle interference imaging of the sample under test based on the second reference beam and the second object beam.

[0010] Furthermore, the light source unit includes a white light source and a collimating lens group. The white light source is a point light source. The white light source projects a light beam onto the collimating lens group, and the light beam is then projected as a parallel light beam onto the beam splitting unit via the collimating lens group.

[0011] Furthermore, the image acquisition unit includes a camera and an eyepiece. The first reference light and the first object light interfere in the field of view of the eyepiece, and the camera acquires the interference image of the sample under test from a first perspective after interference.

[0012] The second reference beam and the second object beam interfere in the field of view of the eyepiece, and the camera acquires the interference image of the sample under test from the second perspective after interference.

[0013] Furthermore, the first sample arm includes a first objective lens, which is used to project a first light beam onto the sample to be tested and to direct the first light beam reflected by the sample to the image acquisition unit.

[0014] Furthermore, the second sample arm includes a second objective lens and a third reflecting mirror. In the second interference unit, the second beam is sequentially projected onto the sample to be tested through the third reflecting mirror and the second objective lens. After being reflected by the sample to be tested, it is sequentially guided to the image acquisition unit through the second objective lens, the third reflecting mirror, and the beam splitting unit.

[0015] Furthermore, the first reference arm includes a second objective lens, a first reflecting mirror, and a first piezoelectric actuator arranged sequentially. The first piezoelectric actuator is used to drive the first reflecting mirror to deform, and the deformation of the first reflecting mirror can change the phase of the light beam reflected to the first reflecting mirror.

[0016] The second beam passes through the second objective lens, is reflected by the first mirror, passes through the second objective lens, and is projected onto the image acquisition unit via the beam splitting unit.

[0017] Furthermore, the second reference arm includes a fourth objective lens, a second reflecting mirror, and a second piezoelectric actuator arranged in sequence. The second piezoelectric actuator is used to drive the second reflecting mirror to deform, and the deformation of the second reflecting mirror can change the phase of the light beam reflected to the second reflecting mirror.

[0018] The second beam passes through the fourth objective lens, is reflected by the second mirror, and then passes through the fourth objective lens before being projected onto the image acquisition unit via the beam splitting unit.

[0019] Furthermore, the beam splitting unit includes a first beam splitter, a second beam splitter, and a third beam splitter arranged sequentially. The first beam splitter and the second beam splitter participate in the interference imaging of the first interference unit, and the first beam splitter, the second beam splitter, and the third beam splitter participate in the interference imaging of the second interference unit.

[0020] Furthermore, the second beam splitter is arranged perpendicular to the first beam splitter, and the third beam splitter is arranged parallel to the first beam splitter.

[0021] Compared with existing technologies, the beneficial effects of this solution are:

[0022] This system is equipped with two interferometric units connected in parallel via a beam splitter. The light beam emitted by the light source unit is reflected and transmitted by the beam splitter to form a first beam and a second beam, respectively. The first beam and the second beam interfere in the first interferometric unit and project an interferometric image about a first perspective of the sample to the image acquisition unit. The second beam interferes in the second interferometric unit and projects an interferometric image about a second perspective of the sample to the image acquisition unit. This system enables simultaneous interferometric imaging of two angles of the sample without changing the position of the object, and covers twice the angle range of the sample without affecting the measurement efficiency, thus expanding the application range of the interferometer. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of an embodiment of the present invention.

[0024] The reference numerals in the accompanying drawings include: white light source 1, collimating lens group 2, first beam splitter 3, camera 4, eyepiece 5, first piezoelectric actuator 6, first reflecting mirror 7, second objective lens 8, second beam splitter 9, third beam splitter 10, fourth objective lens 11, second reflecting mirror 12, second piezoelectric actuator 13, first objective lens 14, sample to be tested 15, third objective lens 16, and third reflecting mirror 17. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments:

[0026] Example:

[0027] A dual-angle parallel interference system, such as Figure 1 As shown, it includes a light source unit, a first interference unit, a beam splitting unit, a second interference unit, and an image acquisition unit.

[0028] The light source unit includes a white light source 1 and a collimating lens group 2. The white light source 1 is a point light source and is used to project a light beam onto the collimating lens group 2. The light beam is then projected as a parallel light beam onto the beam splitting unit via the collimating lens group 2. The light source unit projects a light beam onto the beam splitting unit, and the light beam is reflected and transmitted by the beam splitting unit to form a first light beam and a second light beam, respectively.

[0029] The beam splitting unit includes a first beam splitter 3, a second beam splitter 9, and a third beam splitter 10 arranged sequentially. The mirror surface of the first beam splitter 3 forms a 45° angle with the parallel beam from the collimating lens group 2. The second beam splitter 9 is arranged perpendicular to the first beam splitter 3, and the third beam splitter 10 is arranged parallel to the first beam splitter 3. The first beam splitter 3 and the second beam splitter 9 participate in the interference imaging of the first interference unit, and the first beam splitter 3, the second beam splitter 9, and the third beam splitter 10 participate in the interference imaging of the second interference unit.

[0030] The first interference unit includes a first sample arm and a first reference arm, and the second interference unit includes a second sample arm and a second reference arm; the first sample arm and the second sample arm are located at two different positions of the sample to be tested 15, and are used to acquire the object light from two different angles of the sample to be tested 15, respectively.

[0031] The first sample arm includes a first objective lens 14, which is used to project a first light beam onto the sample 15 to be tested and to guide the first light beam reflected by the sample 15 to the image acquisition unit; the first reference arm includes a second objective lens 8, a first reflector 7 and a first piezoelectric actuator 6 arranged in sequence, which is used to drive the first reflector 7 to deform, and the deformation of the first reflector 7 can change the phase of the light beam reflected to the first reflector 7.

[0032] The second beam passes through the second objective lens 8, is reflected by the first reflecting mirror 7, and then passes through the second objective lens 8 before being projected onto the image acquisition unit via the beam splitting unit.

[0033] The second sample arm includes a second objective lens 8 and a third reflecting mirror. In the second interference unit, the second beam is directed toward the sample to be tested 15 via the third reflecting mirror and the second objective lens 8 in sequence. After being reflected by the sample to be tested 15, the beam is directed toward the image acquisition unit via the second objective lens 8, the third reflecting mirror and the beam splitting unit in sequence.

[0034] The second reference arm includes a fourth objective lens 11, a second reflector 12, and a second piezoelectric actuator 13 arranged in sequence. The second piezoelectric actuator 13 is used to drive the second reflector 12 to deform. The deformation of the second reflector 12 can change the phase of the light beam reflected to the second reflector 12.

[0035] The second beam passes through the fourth objective lens 11, is reflected by the second reflecting mirror 12, and then passes through the fourth objective lens 11 before being projected onto the image acquisition unit via the beam splitting unit.

[0036] The image acquisition unit includes a camera 4 and an eyepiece 5. The first reference light and the first object light interfere in the field of view of the eyepiece 5, and the camera 4 acquires the interference image of the sample 15 under test from the first perspective after interference.

[0037] The second reference beam and the second object beam interfere in the field of view of the eyepiece 5, and the camera 4 acquires the interference image of the sample 15 under test from the second perspective after interference.

[0038] The specific implementation method of this solution is as follows:

[0039] White light source 1 is used to project a light beam onto collimating lens group 2. The light beam is projected into a parallel beam onto first beam splitter 3 via collimating lens group 2. The parallel beam is reflected and transmitted by first beam splitter 3 to form a first beam and a second beam respectively.

[0040] In the first interference unit, the first beam is projected onto the sample 15 under test through the first objective lens 14. The first beam reflected by the sample 15 under test is transmitted to the eyepiece 5 through the first beam splitter 3. The eyepiece 5 obtains the first objective beam about the sample 15 under test.

[0041] The second beam is projected into the first reference arm. Inside the first reference arm, the second beam is projected onto the first mirror via the second beam splitter 9 and the second objective lens 8. After being reflected by the first mirror, it is reflected again via the second objective lens 8, the second beam splitter 9, and the first beam splitter 3 to the eyepiece 5. The eyepiece 5 acquires the first reference beam. The first reference beam and the first objective beam interfere in the field of view of the eyepiece 5. The camera 4 acquires the interference image of the first angle of view of the sample 15 under test after interference.

[0042] In the second interference unit, the second beam is projected onto the sample to be tested 15 via the second beam splitter 9, the third beam splitter 10, the third reflecting mirror, and the third objective lens 16 in sequence. The second beam reflected by the sample to be tested 15 is reflected by the third objective lens 16, the third reflecting mirror, the third beam splitter 10, the second beam splitter 9, and the first beam splitter 3 in sequence to the eyepiece 5. The eyepiece 5 acquires the second objective beam of the sample to be tested 15.

[0043] Simultaneously, the second beam is sequentially projected onto the second reflecting mirror 12 via the second beam splitter 9, the third beam splitter 10, and the fourth objective lens 11. After being reflected by the second reflecting mirror 12, it is reflected again by the fourth objective lens 11, the third beam splitter 10, the second beam splitter 9, and the first beam splitter 3 to the eyepiece 5. The eyepiece 5 acquires the second reference beam, and the second reference beam and the second objective beam interfere in the field of view of the eyepiece 5. The camera 4 acquires the interference image of the second angle of view of the sample 15 under test after interference.

[0044] The interferometric system of this scheme enables simultaneous interferometric imaging of two angles of the sample without changing the position of the object, and covers twice the angular range of the sample without affecting the measurement efficiency, thus expanding the application range of the interferometer.

[0045] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A dual-angle parallel interference system, characterized in that: It includes a light source unit, a first interference unit, a beam splitting unit, a second interference unit, and an image acquisition unit. The light source unit is used to emit a light beam to the beam splitting unit, and the beam splitting unit is used to split the light beam. The first interference unit includes a first sample arm and a first reference arm, and the second interference unit includes a second sample arm and a second reference arm. The first sample arm and the second sample arm are located at two different positions on the sample to be tested, and are used to acquire the object light from two different angles of the sample to be tested. The light source unit projects a light beam onto the beam splitting unit. After reflection and transmission by the beam splitting unit, the light beam forms a first beam and a second beam, respectively. In the first interference unit, the first beam is projected onto the sample under test via the first sample arm. The first beam reflected by the sample under test is projected onto the image acquisition unit via the beam splitting unit. The image acquisition unit acquires a first object beam about the sample under test. The second beam is reflected inside the first reference arm and then projected onto the image acquisition unit via the beam splitting unit. The image acquisition unit acquires a first reference beam and, based on the first reference beam and the first object beam, acquires an interference image of the sample under test from a first viewing angle. In the second interference unit, the second beam is projected onto the sample under test via the second sample arm. The second beam reflected by the sample under test is projected onto the image acquisition unit via the beam splitting unit. The image acquisition unit acquires the second object beam about the sample under test. The second beam is reflected inside the second reference arm and then projected onto the image acquisition unit via the beam splitting unit. The image acquisition unit acquires the second reference beam and acquires the second angle interference imaging of the sample under test based on the second reference beam and the second object beam. The image acquisition unit includes a camera and an eyepiece. The first reference light and the first object light interfere in the field of view of the eyepiece, and the camera acquires the interference image of the sample under test from the first perspective after interference. The second reference beam and the second object beam interfere in the field of view of the eyepiece, and the camera acquires the interference image of the sample under test from the second perspective after interference.

2. The dual-angle parallel interference system according to claim 1, characterized in that: The light source unit includes a white light source and a collimating lens group. The white light source is a point light source. The white light source projects a light beam onto the collimating lens group, and the light beam is then projected as a parallel light beam onto the beam splitting unit via the collimating lens group.

3. The dual-angle parallel interference system according to claim 1, characterized in that: The first sample arm includes a first objective lens, which is used to project a first light beam onto the sample to be tested and to direct the first light beam reflected by the sample to the image acquisition unit.

4. The dual-angle parallel interference system according to claim 1, characterized in that: The second sample arm includes a second objective lens and a third reflecting mirror. In the second interference unit, the second beam is directed toward the sample to be tested via the third reflecting mirror and the second objective lens in sequence. After being reflected by the sample to be tested, it is directed toward the image acquisition unit via the second objective lens, the third reflecting mirror and the beam splitting unit in sequence.

5. A dual-angle parallel interference system according to claim 1, characterized in that: The first reference arm includes a second objective lens, a first reflector, and a first piezoelectric actuator arranged in sequence. The first piezoelectric actuator is used to drive the first reflector to deform. The deformation of the first reflector can change the phase of the light beam reflected to the first reflector. The second beam passes through the second objective lens, is reflected by the first mirror, passes through the second objective lens, and is projected onto the image acquisition unit via the beam splitting unit.

6. The dual-angle parallel interference system according to claim 1, characterized in that: The second reference arm includes a fourth objective lens, a second reflecting mirror, and a second piezoelectric actuator arranged in sequence. The second piezoelectric actuator is used to drive the second reflecting mirror to deform. The deformation of the second reflecting mirror can change the phase of the light beam reflected to the second reflecting mirror. The second beam passes through the fourth objective lens, is reflected by the second mirror, and then passes through the fourth objective lens before being projected onto the image acquisition unit via the beam splitting unit.

7. A dual-angle parallel interference system according to claim 1, characterized in that: The beam splitting unit includes a first beam splitter, a second beam splitter, and a third beam splitter arranged sequentially. The first beam splitter and the second beam splitter participate in the interference imaging of the first interference unit, and the first beam splitter, the second beam splitter, and the third beam splitter participate in the interference imaging of the second interference unit.

8. A dual-angle parallel interference system according to claim 7, characterized in that: The second beam splitter is set perpendicular to the first beam splitter, and the third beam splitter is set parallel to the first beam splitter.

Images