阅读说明：本技术 倾斜斐索波数扫描干涉仪 (Tilted fizeau wave number scanning interferometer ) 是由 周延周 李谦谦 古宇达 于 2020-12-23 设计创作，主要内容包括：本发明提供的一种倾斜斐索波数扫描干涉仪,通过半导体激光器、准直调节镜、参考镜、远心镜头、光谱图像采集器和数据处理部件的设置,基于激光电流波数扫描测量原理实现了测量透镜三维轮廓信息,省去了现有干涉仪中使用的分光棱镜或者半透半反射镜,使结构更加简易,具有很好的稳定性；同时,本发明提供的倾斜斐索波数扫描干涉仪使被测镜和参考镜在同一侧,极大的提高了信噪比。(According to the tilted Fizeau wave number scanning interferometer provided by the invention, the semiconductor laser, the collimation adjusting mirror, the reference mirror, the telecentric lens, the spectral image collector and the data processing component are arranged, the three-dimensional profile information of the lens is measured based on the laser current wave number scanning measurement principle, and a beam splitter prism or a semi-transparent and semi-reflective mirror used in the existing interferometer is omitted, so that the structure is simpler and has good stability; meanwhile, the tilted Fizeau wave number scanning interferometer provided by the invention enables the measured mirror and the reference mirror to be on the same side, thereby greatly improving the signal-to-noise ratio.)

1. The tilted Fizeau wave number scanning interferometer is characterized by comprising a semiconductor laser (1), a collimation adjusting mirror (2), a reference mirror (3), a telecentric lens (4), a spectral image collector (5) and a data processing component (6); wherein:

the semiconductor laser (1) is used for emitting relevant light;

the collimation adjusting mirror (2) collimates the relevant light emitted by the semiconductor laser (1) and guides the adjusted light to be incident to the reference mirror (3);

the related light is reflected in the reference mirror (3), and the reflected light reaches the telecentric lens (4) to form a first reflection light path;

the related light is transmitted to the lens to be detected through the reference mirror (3), reflection is generated on the lens to be detected, and the reflected light reaches the telecentric lens (4) to form a second reflection light path;

the combination of the semiconductor laser (1) and the collimation adjusting mirror (2) is an emission light path; the combination of the telecentric lens (4) and the spectral image collector (5) is a receiving light path; the transmitting light path and the receiving light path are inclined to form a certain angle, so that the first reflecting light path and the second reflecting light path are converged by the telecentric lens (4) to generate interference, and an interference spectrum is generated;

the spectral image collector (5) is used for collecting an interference spectral image;

and the data processing part (6) calculates the three-dimensional profile information of the measured lens according to the acquired interference spectrum image.

2. A tilted fizeau wavenumber scanning interferometer according to claim 1, characterised in that the collimating and conditioning mirror (2) is a plano-convex lens.

3. A tilted fizeau wavenumber scanning interferometer according to claim 1, characterised in that the reference mirror (3) is an optical wedge with a central thickness of 6 mm and an inclination of 10 degrees.

4. A tilted fizeau wavenumber scanning interferometer according to claim 1, characterised in that the spectral image collector (5) is a CMOS camera or a CCD camera.

5. A tilted fizeau wavenumber scanning interferometer according to claim 1, characterised in that the telecentric lens (4) is a double telecentric lens.

6. The tilted fizeau wavenumber scanning interferometer according to any of claims 1 to 5, characterised in that the spectral image collector (5) collects the front and back surfaces S of the reference mirror (3)₁、S₂And front and rear surfaces S of the lens to be measured₃、S₄The light intensity of the interference light after the reflected light of the four surfaces is superposed.

7. The tilted fizeau wavenumber scanning interferometer of claim 6, wherein the data processing means (6) scans the received interference spectral image with a scan wavenumber over time calculated as:

k(t)＝k₀+Δk·t,t∈[0,T]

wherein k is₀The wave number value of the initial output of the laser; Δ k is the range of the laser wavenumber scan.

8. The tilted fizeau wavenumber scanning interferometer according to claim 7, characterised in that in the data processing means (6), the intensity of the interference light collected by the spectral image collector (5) is specified as:

Λ_pq(x,y)＝n_pq·z_pq(x,y)

wherein, I₁、I₂、I₃And I₄Respectively representing the front and rear surfaces S of the reference mirror (3)₁、S₂And front and rear surfaces S of the lens to be measured₃、S₄Reflected light intensity of the four surfaces; lambda_pqIs a surface S_pTo the surface S_qThe optical path difference of (1); n is_pqIs a surface S_pTo the surface S_qAverage refractive index of (a); z is a radical of_pqIs a surface S_pTo the surface S_qThe position difference of (a).

9. The tilted fizeau wavenumber scanning interferometer according to claim 8, characterized in that, in the data processing means (6), after the intensity of the interference light is removed from the direct current component of the intensity, it is rewritten into a matrix form using the euler formula to obtain:

Q＝A·G+W

wherein:

in the formula:

wherein, the coefficient matrix A contains interference frequency information; vector G contains interference phase and interference amplitude information; the vector W represents noise introduced in the acquisition process of the spectral image acquisition device (5), and M represents the total number of surfaces of optical wedges and lenses, namely 4; n is the number of the spectral image collector (5) and the vector Q represents the interference light intensity shot by the spectral image collector (5); separating the interference signals between the surfaces by solving the matrix A and the vector G through the vector Q, thereby obtaining the separationInterference phase phi of mirror profile structure information₁₃。

10. The tilted fizeau wavenumber scanning interferometer of claim 9, wherein the surface S₁And surface S₃The medium between them is air, and the refractive index is 1, then there are:

Φ₁₃＝2·k₀·Λ₁₃

so that the front surface S of the lens₃Profile z of₁₃Expressed as:

z₁₃(x,y)＝Φ₁₃(x,y)/(2·k₀)

and carrying out three-dimensional reconstruction on the three-dimensional profile data of the lens to obtain a three-dimensional profile map of the lens.

Technical Field

The invention relates to the technical field of detection of non-contact optical elements, in particular to a tilted Fizeau wave number scanning interferometer.

Background

With the development of technology, lenses are widely used as precision optical elements in devices such as cameras, projectors, cameras, microscopes, and telescopes. The accuracy of the curved surface of the lens has a close relationship with the imaging quality of equipment, the aberration of the lens with unqualified surface accuracy is increased, and the focus drift and other problems of the zoom lens occur, so that the detection of the surface accuracy of the lens is very important.

At present, the main methods for measuring the three-dimensional profile of the lens comprise a structured light technology, a phase method and a time-of-flight method, wherein the measurement precision of the time-of-flight method is only millimeter level, and the time consumption is long; the structured light technology and the phase method system are complex to construct, have high requirements on projection devices, and are difficult to realize high-precision profile measurement. The phase method is to detect the surface appearance of an object by utilizing the principle of light wave interference and measure the spatial fluctuation change of the optical path difference of the modulation change of the surface appearance of the object in the whole light field. The wavenumber scanning technique is a recently developed interference measuring method, ISHII in Japan in 1980 proposes a semiconductor Laser wavenumber scanning interference scheme for measuring the distance [1] Y.Ishii.wavelet-Tunable Laser-Diode Interferometer [ J ]. OPTICAL REVIEWE,1991,14: 293-. However, the existing interferometer uses a beam splitter prism or a semi-transparent and semi-reflective mirror, so that the structure is complex and the measurement result is unstable.

Disclosure of Invention

The invention provides an inclined Fizeau wave number scanning interferometer, aiming at overcoming the technical defects that a beam splitter prism or a semi-transparent semi-reflecting mirror is used in the existing interferometer, the structure is complex, and the measurement result is unstable.

In order to solve the technical problems, the technical scheme of the invention is as follows:

the tilted Fizeau wave number scanning interferometer comprises a semiconductor laser, a collimation adjusting mirror, a reference mirror, a telecentric lens, a spectral image collector and a data processing component; wherein:

the semiconductor laser is used for emitting related light;

the collimation adjusting mirror collimates the relevant light emitted by the semiconductor laser and guides the adjusted light to be incident to the reference mirror;

the related light is reflected in the reference mirror, and the reflected light reaches the telecentric lens to form a first reflection light path;

the related light is transmitted to the lens to be detected through the reference mirror, reflection is generated on the lens to be detected, and the reflected light reaches the telecentric lens to form a second reflection light path;

the combination of the semiconductor laser and the collimation adjusting lens is an emission light path; the combination of the telecentric lens and the spectral image collector is a receiving light path; the transmitting light path and the receiving light path are inclined to form a certain angle, so that the first reflecting light path and the second reflecting light path are converged by the telecentric lens to generate interference, and an interference spectrum is generated;

the spectral image collector is used for collecting an interference spectral image;

and the data processing part calculates the three-dimensional profile information of the measured lens according to the acquired interference spectrum image.

In the scheme, the invention provides the tilted Fizeau wave number scanning interferometer, which is based on the laser current wave number scanning measurement principle and realizes the measurement of the three-dimensional profile information of the lens; the interferometer has simple structure, simple operation and high signal-to-noise ratio.

And the collimation adjusting lens adopts a plano-convex lens.

Wherein, the reference mirror is an optical wedge with the center thickness of 6 millimeters and the inclination angle of 10 degrees.

The spectral image collector is a CMOS camera or a CCD camera.

And the telecentric lens adopts a double telecentric lens.

In the above scheme, the double telecentric lens is adopted to make the measurement accuracy higher.

Wherein the spectral image collector collects the front and back surfaces S of the reference mirror₁、S₂And front and rear surfaces S of the lens to be measured₃、S₄The light intensity of the interference light after the reflected light of the four surfaces is superposed.

Wherein, the data processing part scans and receives the interference spectrum image, and the calculation process of the change of the scanning wave number along with time is as follows:

k(t)＝k₀+Δk·t,t∈[0,T]

wherein k is₀For laser initiationThe wave number value of the output; Δ k is the range of the laser wavenumber scan.

Wherein, in the data processing part, the interference light intensity collected by the spectrum image collector is specifically represented as:

Λ_pq(x,y)＝n_pq·z_pq(x,y)

wherein, I₁、I₂、I₃And I₄Respectively representing the front and rear surfaces S of the reference mirror₁、S₂And front and rear surfaces S of the lens to be measured₃、S₄Reflected light intensity of the four surfaces; lambda_pqIs a surface S_pTo the surface S_qThe optical path difference of (1); n is_pqIs a surface S_pTo the surface S_qAverage refractive index of (a); z is a radical of_pqIs a surface S_pTo the surface S_qThe position difference of (a).

Wherein, in the data processing part, after removing the direct current component of the light intensity of the interference light, the euler formula is used and the matrix form is rewritten to obtain:

Q＝A·G+W

wherein:

in the formula:

wherein, the coefficient matrix A contains interference frequency information; vector G contains interference phase and interference amplitude information; the vector W represents noise introduced in the acquisition process of the spectral image acquisition device, and M represents the total number of surfaces of an optical wedge and a lens to be 4; n is the number of the spectral image collector, and the vector Q represents the interference light intensity shot by the spectral image collector; solving a matrix A and a vector G through the vector Q, separating interference signals among all surfaces, and obtaining interference phase phi containing lens contour structure information through separation₁₃。

Wherein the surface S₁And surface S₃The medium between them is air, and the refractive index is 1, then there are:

Φ₁₃＝2·k₀·Λ₁₃

so that the front surface S of the lens₃Profile z of₁₃Expressed as:

z₁₃(x,y)＝Φ₁₃(x,y)/(2·k₀)

and carrying out three-dimensional reconstruction on the three-dimensional profile data of the lens to obtain a three-dimensional profile map of the lens.

Compared with the prior art, the technical scheme of the invention has the beneficial effects that:

according to the tilted Fizeau wave number scanning interferometer provided by the invention, the semiconductor laser, the collimation adjusting mirror, the reference mirror, the telecentric lens, the spectral image collector and the data processing component are arranged, the three-dimensional profile information of the lens is measured based on the laser current wave number scanning measurement principle, and a beam splitter prism or a semi-transparent and semi-reflective mirror used in the existing interferometer is omitted, so that the structure is simpler and has good stability; meanwhile, the tilted Fizeau wave number scanning interferometer provided by the invention enables the measured mirror and the reference mirror to be on the same side, thereby greatly improving the signal-to-noise ratio.

Drawings

FIG. 1 is a schematic diagram of a tilted Fizeau wavenumber scanning interferometer according to the present invention;

wherein: 1. a semiconductor laser; 2. a collimation adjustment mirror; 3. a reference mirror; 4. a telecentric lens; 5. a spectral image collector; 6. a data processing section; 7. and (5) a lens to be measured.

Detailed Description

The drawings are for illustrative purposes only and are not to be construed as limiting the patent;

for the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product;

it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The technical solution of the present invention is further described below with reference to the accompanying drawings and examples.

Example 1

The invention provides a tilted Fizeau wave number scanning interferometer, which comprises a semiconductor laser 1, a collimation adjusting mirror 2, a reference mirror 3, a telecentric lens 4, a spectral image collector 5 and a data processing part 6, wherein the semiconductor laser is arranged on the upper surface of the reference mirror; wherein:

the semiconductor laser 1 is used for emitting relevant light;

the collimation adjusting mirror 2 collimates the relevant light emitted by the semiconductor laser 1 and guides the adjusted light to be incident to the reference mirror 3;

the related light is reflected in the reference mirror 3, and the reflected light reaches the telecentric lens 4 to form a first reflection light path;

the related light is transmitted to a measured lens 7 through the reference mirror 3, reflection is generated on the measured lens 7, and the reflected light reaches the telecentric lens 4 to form a second reflection light path;

the combination of the semiconductor laser 1 and the collimation adjusting mirror 2 is an emission light path; the combination of the telecentric lens 4 and the spectral image collector 5 is a receiving light path; the transmitting light path and the receiving light path are inclined to form a certain angle, so that the first reflecting light path and the second reflecting light path are converged by the telecentric lens 4 to generate interference, and an interference spectrum is generated;

the spectral image collector 5 is used for collecting interference spectral images;

the data processing part 6 calculates three-dimensional profile information of the measured lens 7 according to the acquired interference spectrum image.

In a specific implementation process, the invention provides a tilted Fizeau wave number scanning interferometer, which is based on a laser current wave number scanning measurement principle and realizes the measurement of three-dimensional profile information of a lens; the interferometer has simple structure, simple operation and high signal-to-noise ratio.

More specifically, the collimation adjusting mirror 2 adopts a plano-convex lens.

More specifically, the reference mirror 3 is an optical wedge with a center thickness of 6 mm and an inclination angle of 10 degrees.

More specifically, the spectral image acquirer 5 is a CMOS camera or a CCD camera.

More specifically, the telecentric lens 4 is a double telecentric lens.

In the specific implementation process, the double telecentric lens 4 is adopted, so that the measurement accuracy is higher.

More specifically, the spectral image collector 5 collects the front and back surfaces S of the reference mirror 3₁、S₂And front and rear surfaces S of the lens 7 to be measured₃、S₄The light intensity of the interference light after the reflected light of the four surfaces is superposed.

More specifically, the data processing unit 6 scans and receives the interference spectrum image, and the calculation process of the variation of the scanning wave number along with time is as follows:

k(t)＝k₀+Δk·t,t∈[0,T]

wherein k is₀The wave number value of the initial output of the laser; Δ k is the range of laser wavenumber scanning;

more specifically, in the data processing unit 6, the light intensity of the interference light collected by the spectral image collector 5 is specifically represented as:

Λ_pq(x,y)＝n_pq·z_pq(x,y)

wherein, I₁、I₂、I₃And I₄Respectively representing the front and rear surfaces S of the reference mirror₁、S₂And front and rear surfaces S of the lens to be measured₃、S₄Reflected light intensity of the four surfaces; lambda_pqIs a surface S_pTo the surface S_qThe optical path difference of (1); n is_pqIs a surface S_pTo the surface S_qAverage refractive index of (a); z is a radical of_pqIs a surface S_pTo the surface S_qThe position difference of (a).

More specifically, in the data processing unit 6, after the direct current component of the light intensity of the interference light is removed, the direct current component is rewritten into a matrix form by using the euler formula, so as to obtain:

Q＝A·G+W

wherein:

in the formula:

wherein, the coefficient matrix A contains interference frequency information; vector G contains interference phase and interference amplitude information; the vector W represents noise introduced in the acquisition process of the spectral image acquisition device, and M represents the total number of surfaces of an optical wedge and a lens to be 4; n is a spectrogramThe number of the images shot by the image collector is counted, and the vector Q represents the interference light intensity shot by the spectral image collector; solving a matrix A and a vector G through the vector Q, separating interference signals among all surfaces, and obtaining interference phase phi containing lens contour structure information through separation₁₃。

More specifically, the surface S₁And surface S₃The medium between them is air, and the refractive index is 1, then there are:

Φ₁₃＝2·k₀·Λ₁₃

so that the front surface S of the lens₃Profile z of₁₃Expressed as:

z₁₃(x,y)＝Φ₁₃(x,y)/(2·k₀)

and carrying out three-dimensional reconstruction on the three-dimensional profile data of the lens to obtain a three-dimensional profile map of the lens.

In a specific implementation process, the tilted Fizeau wave number scanning interferometer provided by the invention realizes the measurement of three-dimensional profile information of a lens based on a laser current wave number scanning measurement principle by arranging the semiconductor laser 1, the collimation adjusting mirror 2, the reference mirror 3, the telecentric lens 4, the spectral image collector 5 and the data processing component 6, and omits a beam splitter prism or a semi-transparent semi-reflecting mirror used in the existing interferometer, so that the structure is simpler and has good stability; meanwhile, the tilted Fizeau wave number scanning interferometer provided by the invention enables the measured mirror and the reference mirror to be on the same side, thereby greatly improving the signal-to-noise ratio.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.