Three-dimensional line imaging device and method

Abstract

A three-dimensional line imaging device and method, belonging to the field of optical detection technology, combines chromatic aberration technology and spectral domain interferometry technology to achieve scanning imaging, and has the characteristics of high vertical and horizontal resolution and a large dynamic measurement range. To address the contradiction that the chromatic aberration effect requires a light source with a larger line width, which results in a smaller depth measurement range of spectral domain interferometry, the present invention introduces four reference arms to increase the detection depth. At the same time, to eliminate interference between the four reference arms of spectral domain interferometry, chromatic aberration technology is first used to determine the low-precision depth value and the reference arms involved in the interference. Then, spectral domain interferometry is used to calculate the high-precision relative depth value, and the results of the spectral domain interferometry are offset compensated to obtain accurate depth information, thereby effectively increasing the measurement range of spectral domain interferometry. By determining the depth of the sample at any point within the spectral measurement range, the line profile distribution of the sample on the assembly line is obtained, and ultimately three-dimensional line imaging measurement of moving objects is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical detection, and in particular relates to a three-dimensional line imaging device and method. Background Art

[0002] In industrial production, there's often a need to perform 3D surface profile detection on items on assembly lines. Since items on assembly lines are in motion, traditional point scanning and surface scanning methods, which require the objects to be stationary, can't meet these requirements. Line imaging can capture the contour distribution of a line at once, allowing it to scan and image objects along the assembly line. Therefore, line imaging can meet the need for contour detection on items on assembly lines.

[0003] US patent application publication number US8786836B2 discloses a three-dimensional line imaging technique based on a chromatic confocal method. Based on the principle of chromatic confocality, this approach utilizes a chromatic lens to amplify chromatic aberration, focusing probe light of different wavelengths at different locations to form a series of monochromatic light focal points. This creates a one-to-one correspondence between distance and wavelength, while simultaneously focusing the linear light onto the sample surface to achieve three-dimensional line imaging. However, this patent still suffers from technical issues such as poor objective lens imaging quality, light source spectral amplitude jitter, and systematic ineffective chromatic aberration interference, which affect measurement accuracy. Its longitudinal resolution is limited by the detection range, making it impossible to achieve high-resolution measurements over a large displacement measurement range. Furthermore, because the relationship between wavelength and distance is nonlinear and is affected by the parameters of the chromatic lens, the relationship between wavelength and displacement requires complex, high-precision calibration. Furthermore, the incident and reflected probe light have a certain angle, making it unsuitable for samples with steep structures.

[0004] The Chinese patent application with the publication number CN113654482A discloses an optical 3D imaging device and method based on chromatic aberration and spectral domain interferometry. It proposes to combine spectral domain interferometry technology and chromatic aberration confocal technology for scanning imaging. However, this solution is based on point measurement combined with galvanometer scanning, which requires the sample to be stationary, so it cannot be applied to the assembly line. At the same time, its chromatic aberration confocal requires a larger light source line width to enhance the chromatic aberration effect in order to achieve a large longitudinal measurement range. However, the theoretical longitudinal measurement range of spectral domain interferometry technology is expressed as Where N is the number of pixels in the spectrometer, Δλ is the line width of the light source, and λ C is the central wavelength of the light source. From this expression, we can see that spectral domain interferometry technology requires a smaller linewidth to achieve a large measurement range. Obviously, the above scheme is in conflict with the requirements for the light source in spectral domain interferometry technology, resulting in the above scheme being unable to achieve high precision and a large longitudinal measurement range.

[0005] A Chinese patent application with the announcement number CN113251945A discloses a demodulation method and imaging device for line profile imaging. This solution is based on spectral domain interferometry technology. By obtaining the interference spectrum on the measured object and calculating the horizontal coordinate ordinal number of the maximum point of the amplitude spectrum, the phase of the sub-spectral spectrum of the interference spectrum is calculated, and then the line profile distribution is calculated and corrected. A relatively narrow low-coherence light source is used to generate linear light to achieve measurement and imaging. However, compared with chromatic aberration confocal technology, this solution has the disadvantages of low lateral resolution and a small measurable range, and cannot solve the contradiction between measurement range and accuracy. In addition, the detection depth of traditional spectral domain white light interferometry is small, and multiple reference arms are usually used for splicing to increase the measurement range. However, traditional multiple reference arms will cause multiple interference signals to be superimposed and difficult to process. It is necessary to control one reference arm separately at a time, which results in a long measurement time and can only measure static samples. Summary of the Invention

[0006] To address the problems of the existing technology, the present invention provides a three-dimensional line imaging device and method that combines chromatic aberration technology and spectral domain interferometry technology to achieve scanning imaging, characterized by high vertical and horizontal resolution and a large dynamic measurement range. To address the contradiction between the chromatic aberration effect requiring a light source with a larger line width, which results in a smaller depth measurement range for spectral domain interferometry, the present invention introduces four reference arms to increase the detection depth. At the same time, to eliminate interference between the four reference arms of spectral domain interferometry, chromatic aberration technology is first used to determine the low-precision depth value and the reference arms involved in the interference. Spectral domain interferometry is then used to calculate the high-precision relative depth value, and the spectral domain interferometry result is offset compensated to obtain accurate depth information, thereby effectively increasing the measurement range of spectral domain interferometry and meeting the measurement requirements of moving objects.

[0007] In order to achieve the above-mentioned object, the present invention adopts the following technical solution: a three-dimensional line imaging device, comprising a broadband light source, a first lens, a first cylindrical lens, a first slit, a first beam splitter, a chromatic aberration lens, a second cylindrical lens, a second lens, a second beam splitter, a third beam splitter, a first filter, a third lens, a first reflector, a second filter, a fourth lens, a second reflector, a fourth beam splitter, a third filter, a fifth lens, a third reflector, a fourth filter, a sixth lens, a fourth reflector, a seventh lens, a second slit, an eighth lens, a grating, a ninth lens, an area array camera, a computer and a fifth reflector; light emitted by the broadband light source is collimated by the first lens and then emitted to the first cylindrical lens. The lens is configured such that a linear light is emitted from the first cylindrical lens, the linear light is focused on the first slit, the stray light is filtered out by the first slit and then emitted to the first beam splitter, and the sample light and the reference light are emitted from the first beam splitter respectively; the sample light emitted from the first beam splitter is emitted to the chromatic aberration lens, and the linear light emitted from the chromatic aberration lens is focused on the sample; the reference light emitted from the first beam splitter is emitted to the second cylindrical lens, and the reference light emitted from the second cylindrical lens is collimated by the second lens and then emitted to the second beam splitter; the reference light emitted from the second beam splitter is emitted to the third beam splitter and the fourth beam splitter respectively; the reference light emitted from the third beam splitter is emitted to the first filter and the second filter respectively; the reference light emitted from the fourth beam splitter is emitted to the third beam splitter. The light is incident on the third filter and the fourth filter respectively; the reference light emitted by the first filter is focused by the third lens and then emitted to the first reflector; the reference light emitted by the second filter is focused by the fourth lens and then emitted to the second reflector; the reference light emitted by the third filter is focused by the fifth lens and then emitted to the third reflector; the reference light emitted by the fourth filter is focused by the sixth lens and then emitted to the fourth reflector; the first filter, the third lens and the first reflector constitute a first reference arm; the second filter, the fourth lens and the second reflector constitute a second reference arm; the third filter, the fifth lens and the third reflector constitute a third reference arm; the fourth filter , the sixth lens and the fourth reflector constitute a fourth reference arm; the sample light reflected by the sample returns to the first beam splitter along the original path; the reference light reflected by the first reflector, the second reflector, the third reflector and the fourth reflector returns to the first beam splitter along the original path; the reflected sample light and the reference light are merged by the first beam splitter and then emitted to the seventh lens, focused by the seventh lens and then emitted to the second slit, stray light is filtered out by the second slit and then emitted to the eighth lens, collimated by the eighth lens and reflected by the fifth reflector into the grating, split by the grating and focused by the ninth lens and then emitted to the area array camera, the area array camera is electrically connected to the computer, the interference image is collected by the area array camera, and the interference image is demodulated by the computer.

[0008] A three-dimensional line imaging method, using the three-dimensional line imaging device, comprises the following steps:

[0009] Step S1: Determine the relationship between chromatic aberration and depth; first, set the spectral measurement range to AE, then divide the spectral measurement range AE into four equal parts, namely AB spectral segment, BC spectral segment, CD spectral segment, and DE spectral segment, and AB = BC = CD = DE; wherein, the spectral positions corresponding to the depths of AB, BC, CD, and DE are set to λ A -λ B ,λ B -λ C ,λ C -λ D ,λ D -λ E ;

[0010] Step S2: Determine the positions of the four reference arms; the depth position reference points of the reflectors are represented by A, B, C, and D in sequence; first, determine the position of the first reflector in the first reference arm, select a debugging reflector, and place the debugging reflector at a depth position A1 below the chromatic aberration lens, then move the positions of the first filter, the third lens, and the first reflector until the reference light reflected by the first reflector and the sample light reflected by the debugging reflector reach the same optical path; then, determine the position of the second reflector in the second reference arm, place the debugging reflector at a depth position B1 below the chromatic aberration lens, then move the positions of the second filter, the fourth lens, and the second reflector until the reference light reflected by the second reflector and the sample light reflected by the debugging reflector reach the same optical path. ; Afterwards, determine the position of the third reflector in the third reference arm, place the debugging reflector at a depth position C1 below the chromatic aberration lens, and then move the positions of the third filter, the fifth lens, and the third reflector until the reference light reflected by the third reflector and the sample light reflected by the debugging reflector reach the same optical path; finally, determine the position of the fourth reflector in the fourth reference arm, place the debugging reflector at a depth position D1 below the chromatic aberration lens, and then move the positions of the fourth filter, the sixth lens, and the fourth reflector until the reference light reflected by the fourth reflector and the sample light reflected by the debugging reflector reach the same optical path; at this time, the reflector depth position reference points A, B, C, and D are offset relative to the reflector depth position setting points A1, B1, C1, and D1;

[0011] Step S3: Block the sample light and obtain the interference spectra of four reference lights, which are respectively recorded as the first reference light, the second reference light, the third reference light, and the fourth reference light; since the transmission spectrum of the first reference light only overlaps with the transmission spectrum of the second reference light, the reflected first reference light only interferes with the reflected second reference light, and the interference spectrum appears in the overlapping area of ​​the two transmission spectra; similarly, the interference spectrum of the reflected second reference light and the reflected third reference light appears in the overlapping area of ​​the two transmission spectra, and the interference spectrum of the reflected third reference light and the reflected fourth reference light appears in the overlapping area of ​​the two transmission spectra. The optical path difference between the second and third reflectors relative to the first reflector is D21, the optical path difference between the third and third reflectors relative to the second reflector is D32, and the optical path difference between the fourth and fourth reflectors relative to the third reflector is D43. Therefore, the offset of the first reference arm is 0, the offset of the second reference arm relative to the first reference arm is D21, the offset of the third reference arm relative to the first reference arm is D21+D32, and the offset of the fourth reference arm relative to the first reference arm is D21+D32+D43.

[0012] Step S4: Set the line profile distribution on the sample as H(x), where x represents the coordinates of different points on the sample on the linear detection light; set the interference image obtained by the computer as I(k i ,x),I(k i , x) represents the interference spectrum formed by the sample light and the reference light reflected by the point with coordinate x on the sample line; where k i is the horizontal coordinate of the interference image, k i represents the wave number corresponding to the i-th pixel in the lateral direction of the spectrum, and i=1, 2, 3, etc.; for the interference image I(k i , x) is processed separately to obtain the height of the point; assuming the depth of the sample is H1, according to the envelope of the interference spectrum, the horizontal coordinate of the maximum value of the interference spectrum is determined to be λ0, and λ0 is located at λ A and λ B Based on the relationship between wavelength and depth in chromatic aberration technology, it is determined that the depth H1 of the sample is within the AB spectral band. Therefore, it can be determined that the interference spectrum is the interference spectrum of the sample light and the first reference light. Then, the relative depth obtained by demodulating the interference spectrum is set as L1. The depth H1 of the sample is equal to the relative depth L1 plus the offset of the first reference arm.

[0013] Step S5: Assuming that the depth of the sample is H2, the interference spectrum appears in the interval where the transmission spectrum of the first reference arm and the second reference arm overlap, and then according to the envelope of the interference spectrum, the wavelength λ1 corresponding to the maximum value of the interference spectrum is determined. λ1 is located at λ A and λ CAccording to the relationship between wavelength and depth in the chromatic aberration technology, it is determined that the depth H2 of the sample is within the AC spectral band; since the sample light interferes with the first reference light and the second reference light respectively, two peaks will appear in the interference spectrum after fast Fourier transform; since the depth H2 of the sample is far from the equal optical path point of the first reflector and close to the equal optical path point of the second reflector, the frequency of the interference spectrum between the sample light and the first reference light is higher, and the frequency of the interference spectrum between the sample light and the second reference light is lower; then the interference spectrum between the sample light and the first reference light is obtained by high-pass filtering, and the relative depth demodulated by the interference spectrum is set to L2, then the depth H2 of the sample is equal to the relative depth L2 plus the offset of the first reference arm;

[0014] Step S6: Assuming that the depth of the sample is H4, determine the wavelength λ2 corresponding to the maximum value of the interference spectrum according to the envelope of the interference spectrum. λ2 is located at λ D and λ E According to the relationship between wavelength and depth in the chromatic aberration technique, the depth H4 of the sample is determined to be within the DE spectral band. Then, the relative depth obtained by demodulating the interference spectrum is set as L4. The depth H4 of the sample is equal to the relative depth L4 plus the offset of the fourth reference arm.

[0015] Step S7: Similarly, the depth of the sample at any point between the spectral measurement range AE is obtained, and then the line profile distribution of the sample is obtained, and finally the three-dimensional line imaging measurement of the moving object is realized.

[0016] Beneficial effects of the present invention:

[0017] The three-dimensional line imaging device and method of the present invention combine chromatic aberration technology and spectral domain interferometry to achieve scanning imaging, featuring high vertical and horizontal resolution and a large dynamic measurement range. To address the contradiction between the chromatic aberration effect requiring a light source with a larger linewidth and the resulting smaller depth measurement range of spectral domain interferometry, the present invention introduces four reference arms to increase the detection depth. To eliminate interference between the four reference arms of spectral domain interferometry, chromatic aberration technology is first used to determine a low-precision depth value and identify the reference arms involved in the interference. Spectral domain interferometry is then used to calculate a high-precision relative depth value, and the spectral domain interferometry result is offset compensated to obtain precise depth information. This effectively increases the measurement range of spectral domain interferometry and meets the requirements for measuring moving objects. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the structure of a three-dimensional line imaging device of the present invention;

[0019] Figure 2 Schematic diagram of the corresponding relationship between color difference and depth;

[0020] Figure 3 The corresponding spectral position diagram of the four reference arms;

[0021] Figure 4 Schematic diagram for determining the position of the reference arm reflector;

[0022] Figure 5 Schematic diagram of sample position (when the sample depth is set to H1);

[0023] Figure 6 Schematic diagram of sample position (when the sample depth is set to H2);

[0024] Figure 7 Schematic diagram of the amplitude spectrum of the interference spectrum;

[0025] Figure 8 Schematic diagram of sample position (when the sample depth is set to H4);

[0026] In the figure, 1 is a broadband light source, 2 is a first lens, 3 is a first cylindrical lens, 4 is a first slit, 5 is a first beam splitter, 6 is a chromatic aberration lens, 7 is a second cylindrical lens, 8 is a second lens, 9 is a second beam splitter, 10 is a third beam splitter, 11 is a first filter, 12 is a third lens, 13 is a first reflector, 14 is a second filter, 15 is a fourth lens, 16 is a second reflector, 17 is a fourth beam splitter, 18 is a third filter, 19 is a fifth lens, 20 is a third reflector, 21 is a fourth filter, 22 is a sixth lens, 23 is a fourth reflector, 24 is a seventh lens, 25 is a second slit, 26 is an eighth lens, 27 is a grating, 28 is a ninth lens, 29 is an area array camera, 30 is a computer, 31 is a fifth reflector, and 32 is a sample. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] like Figure 1As shown, a three-dimensional line imaging device includes a broadband light source 1, a first lens 2, a first cylindrical lens 3, a first slit 4, a first beam splitter 5, a chromatic aberration lens 6, a second cylindrical lens 7, a second lens 8, a second beam splitter 9, a third beam splitter 10, a first filter 11, a third lens 12, a first reflector 13, a second filter 14, a fourth lens 15, a second reflector 16, a fourth beam splitter 17, a third filter 18, a fifth lens 19, a third reflector 20, a fourth filter 21, a sixth lens 22, a fourth reflector 23, a seventh lens 24, a second slit 25, an eighth lens 26, a grating 27, a ninth lens 28, an area array camera 29, Computer 30 and fifth reflector 31; the light emitted by the broadband light source 1 is collimated by the first lens 2 and then emitted to the first cylindrical lens 3, and the linear light is emitted by the first cylindrical lens 3, and the linear light is focused on the first slit 4. The stray light is filtered out by the first slit 4 and then emitted to the first beam splitter 5, and the first beam splitter 5 emits sample light and reference light respectively; the sample light emitted by the first beam splitter 5 is emitted to the chromatic aberration lens 6, and the linear light emitted by the chromatic aberration lens 6 is focused on the sample 32; the reference light emitted by the first beam splitter 5 is emitted to the second cylindrical lens 7, and the reference light emitted by the second cylindrical lens 7 is collimated by the second lens 8 and then emitted to the second beam splitter 9; the reference light emitted by the second beam splitter 9 The light is incident on the third beam splitter 10 and the fourth beam splitter 17 respectively; the reference light emitted by the third beam splitter 10 is incident on the first filter 11 and the second filter 14 respectively; the reference light emitted by the fourth beam splitter 17 is incident on the third filter 18 and the fourth filter 21 respectively; the reference light emitted by the first filter 11 is focused by the third lens 12 and then emitted to the first reflector 13; the reference light emitted by the second filter 14 is focused by the fourth lens 15 and then emitted to the second reflector 16; the reference light emitted by the third filter 18 is focused by the fifth lens 19 and then emitted to the third reflector 20; the reference light emitted by the fourth filter 21 is focused by the sixth lens 2 2 is focused and then emitted to the fourth reflector 23; the first filter 11, the third lens 12 and the first reflector 13 form a first reference arm; the second filter 14, the fourth lens 15 and the second reflector 16 form a second reference arm; the third filter 18, the fifth lens 19 and the third reflector 20 form a third reference arm; the fourth filter 21, the sixth lens 22 and the fourth reflector 23 form a fourth reference arm; the sample light reflected by the sample 32 returns to the first beam splitter 5 along the original path; the reference light reflected by the first reflector 13, the second reflector 16, the third reflector 20 and the fourth reflector 23 returns to the first beam splitter 5 along the original path;The reflected sample light and reference light are combined by the first beam splitter 5 and then directed to the seventh lens 24. Seventh lens 24 focuses the light and then directs it to the second slit 25. Stray light is filtered out by the second slit 25 and then directed to the eighth lens 26. After being collimated by the eighth lens 26, the light is reflected by the fifth reflector 31 and enters the grating 27. After being split by the grating 27, the light is focused by the ninth lens 28 and then directed to the area array camera 29. The area array camera 29 is electrically connected to a computer 30. The area array camera 29 captures the interference image, and the computer 30 demodulates the interference image.

[0029] A three-dimensional line imaging method, using the three-dimensional line imaging device, comprises the following steps:

[0030] Step S1: Determine the relationship between color difference and depth; Figure 2 As shown in the figure, the spectral measurement range is first set to AE, and then the spectral measurement range AE is divided into four equal parts, which are respectively recorded as AB spectral segment, BC spectral segment, CD spectral segment and DE spectral segment, and AB=BC=CD=DE; among which, the spectral positions corresponding to the depths of AB, BC, CD and DE are set to λ A -λ B ,λ B -λ C ,λ C -λ D and λ D -λ E ;like Figure 3 , which are transmission spectra of the first reference arm, the second reference arm, the third reference arm, and the fourth reference arm, wherein the transmission spectrum of the first reference arm is represented by a solid line, the transmission spectrum of the second reference arm is represented by a dotted line, the transmission spectrum of the third reference arm is represented by a dashed line, and the transmission spectrum of the fourth reference arm is represented by a dashed-dotted line;

[0031] Step S2: Determine the positions of the four reference arms; Figure 4As shown, the depth position reference points of the reflector are represented by A, B, C and D in sequence; first, the position of the first reflector 13 in the first reference arm is determined, and a debugging reflector is selected, and the debugging reflector is placed at the depth position A1 below the chromatic aberration lens 6, and then the positions of the first filter 11, the third lens 12 and the first reflector 13 are moved until the reference light reflected by the first reflector 13 and the sample light reflected by the debugging reflector reach the same optical path; then, the position of the second reflector 16 in the second reference arm is determined, and the debugging reflector is placed at the depth position B1 below the chromatic aberration lens 6, and then the positions of the second filter 14, the fourth lens 15 and the second reflector 16 are moved until the reference light reflected by the second reflector 16 and the sample light reflected by the debugging reflector reach the same optical path; thereafter, the position of the second reflector 16 in the second reference arm is determined, and the debugging reflector is placed at the depth position B1 below the chromatic aberration lens 6, and then the positions of the second filter 14, the fourth lens 15 and the second reflector 16 are moved until the reference light reflected by the second reflector 16 and the sample light reflected by the debugging reflector reach the same optical path; The position of the third reflector 20 in the three reference arms is determined, and the debugging reflector is placed at a depth position C1 below the chromatic aberration lens 6. The third filter 18, the fifth lens 19, and the third reflector 20 are then moved until the reference light reflected by the third reflector 20 and the sample light reflected by the debugging reflector reach equal optical path lengths. Finally, the position of the fourth reflector 23 in the fourth reference arm is determined, and the debugging reflector is placed at a depth position D1 below the chromatic aberration lens 6. The fourth filter 21, the sixth lens 22, and the fourth reflector 23 are then moved until the reference light reflected by the fourth reflector 23 and the sample light reflected by the debugging reflector reach equal optical path lengths. At this time, the reflector depth position reference points A, B, C, and D are offset relative to the reflector depth position setting points A1, B1, C1, and D1.

[0032] Step S3: Block the sample light and obtain the interference spectra of four reference lights, which are respectively recorded as the first reference light, the second reference light, the third reference light, and the fourth reference light; since the transmission spectrum of the first reference light only overlaps with the transmission spectrum of the second reference light, the reflected first reference light only interferes with the reflected second reference light, and the interference spectrum appears in the area where the two transmission spectra overlap; similarly, the interference spectrum of the reflected second reference light and the reflected third reference light appears in the area where the two transmission spectra overlap, and the interference spectrum of the reflected third reference light and the reflected fourth reference light appears in the area where the two transmission spectra overlap. Finally, based on the interference spectra of the four reference lights, the optical path difference of the second reflecting mirror 16 relative to the first reflecting mirror 13 is D21, the optical path difference of the third reflecting mirror 20 relative to the second reflecting mirror 16 is D32, and the optical path difference of the fourth reflecting mirror 23 relative to the third reflecting mirror 20 is D43. Therefore, the offset of the first reference arm is 0, the offset of the second reference arm relative to the first reference arm is D21, the offset of the third reference arm relative to the first reference arm is D21+D32, and the offset of the fourth reference arm relative to the first reference arm is D21+D32+D43.

[0033] Step S4: Set the line profile distribution on the sample 32 as H(x), where x represents the coordinates of different points on the sample 32 on the linear detection light; set the interference image obtained by the computer 30 as I(k i ,x),I(k i , x) represents the interference spectrum formed by the sample light and the reference light reflected by the point with coordinate x on the sample line 32; where k i is the horizontal coordinate of the interference image, k i represents the wave number corresponding to the i-th pixel in the lateral direction of the spectrum, and i=1, 2, 3, etc.; for the interference image I(k i , x) is processed separately to obtain the height of the point; Figure 5 As shown, assuming that the depth of the sample 32 is H1, according to the envelope of the interference spectrum, the horizontal coordinate of the maximum value of the interference spectrum is determined to be λ0, and λ0 is located at λ A and λ B Based on the relationship between wavelength and depth in chromatic aberration technology, it is determined that the depth H1 of the sample 32 is within the AB spectral band. Therefore, it can be determined that the interference spectrum is the interference spectrum of the sample light and the first reference light. Then, the relative depth obtained by demodulating the interference spectrum is set as L1. The depth H1 of the sample 32 is equal to the relative depth L1 plus the offset of the first reference arm.

[0034] Step S5: Figure 6 As shown in the figure, assuming that the depth of the sample 32 is H2, the interference spectrum appears in the interval where the transmission spectrum of the first reference arm and the second reference arm overlap. Then, according to the envelope of the interference spectrum, the wavelength λ1 corresponding to the maximum value of the interference spectrum is determined. λ1 is located at λ A and λ C According to the relationship between wavelength and depth in the chromatic aberration technology, it is determined that the depth H2 of the sample 32 is located in the AC spectrum band; since the sample light interferes with the first reference light and the second reference light respectively, two peaks will appear in the interference spectrum after fast Fourier transform, such as Figure 7 As shown; since the depth H2 of the sample 32 is far from the equal-path point of the first reflector 13 and close to the equal-path point of the second reflector 16, the interference spectrum frequency of the sample light and the first reference light is higher, and the interference spectrum frequency of the sample light and the second reference light is lower; then, the interference spectrum of the sample light and the first reference light is obtained by high-pass filtering, and the relative depth demodulated by the interference spectrum is set to L2, then the depth H2 of the sample 32 is equal to the relative depth L2 plus the offset of the first reference arm;

[0035] Step S6: Figure 8 As shown, assuming that the depth of the sample 32 is H4, the wavelength λ2 corresponding to the maximum value of the interference spectrum is determined according to the envelope of the interference spectrum. λ2 is located at λ D and λ EAccording to the relationship between wavelength and depth in the chromatic aberration technique, it is determined that the depth H4 of the sample 32 is within the DE spectral band. Then, the relative depth obtained by demodulating the interference spectrum is set as L4. The depth H4 of the sample 32 is equal to the relative depth L4 plus the offset of the fourth reference arm.

[0036] Step S7: Similarly, the depth of the sample 32 at any point between the spectral measurement range AE is obtained, and then the line profile distribution of the sample 32 is obtained, and finally the three-dimensional line imaging measurement of the moving object is realized.

[0037] The solutions in the embodiments are not intended to limit the patent protection scope of the present invention. Any equivalent implementation or modification that does not deviate from the present invention is included in the patent scope of this case.

Claims

1. A three-dimensional line imaging device, characterized in that: The invention comprises a broadband light source, a first lens, a first cylindrical lens, a first slit, a first beam splitter, a chromatic aberration lens, a second cylindrical lens, a second lens, a second beam splitter, a third beam splitter, a first filter, a third lens, a first reflector, a second filter, a fourth lens, a second reflector, a fourth beam splitter, a third filter, a fifth lens, a third reflector, a fourth filter, a sixth lens, a fourth reflector, a seventh lens, a second slit, an eighth lens, a grating, a ninth lens, an area array camera, a computer and a fifth reflector; light emitted by the broadband light source is collimated by the first lens and then emitted to the first cylindrical lens, and linear light is emitted by the first cylindrical lens, and the linear light is focused on the first cylindrical lens. A slit is formed, stray light is filtered out by the first slit and then emitted to the first beam splitter, and the first beam splitter emits sample light and reference light respectively; the sample light emitted by the first beam splitter is emitted to the chromatic aberration lens, and the linear light emitted by the chromatic aberration lens is focused on the sample; the reference light emitted by the first beam splitter is emitted to the second cylindrical lens, and the reference light emitted by the second cylindrical lens is collimated by the second lens and then emitted to the second beam splitter; the reference light emitted by the second beam splitter is emitted to the third beam splitter and the fourth beam splitter respectively; the reference light emitted by the third beam splitter is emitted to the first filter and the second filter respectively; the reference light emitted by the fourth beam splitter is emitted to the third filter and the fourth filter respectively. The reference light emitted by the first filter is focused by the third lens and then emitted to the first reflecting mirror; the reference light emitted by the second filter is focused by the fourth lens and then emitted to the second reflecting mirror; the reference light emitted by the third filter is focused by the fifth lens and then emitted to the third reflecting mirror; the reference light emitted by the fourth filter is focused by the sixth lens and then emitted to the fourth reflecting mirror; the first reference arm is composed of the first filter, the third lens and the first reflecting mirror; the second reference arm is composed of the second filter, the fourth lens and the second reflecting mirror; the third reference arm is composed of the third filter, the fifth lens and the third reflecting mirror; the fourth filter, the sixth lens and the third reflecting mirror are Four reflectors form a fourth reference arm; the sample light reflected by the sample returns to the first beam splitter along the original path; the reference light reflected by the first, second, third and fourth reflectors returns to the first beam splitter along the original path; the reflected sample light and reference light are combined by the first beam splitter and then emitted to the seventh lens, focused by the seventh lens and then emitted to the second slit, stray light is filtered out by the second slit and then emitted to the eighth lens, collimated by the eighth lens and reflected by the fifth reflector into the grating, split by the grating and focused by the ninth lens and then emitted to the area array camera, the area array camera is electrically connected to a computer, the interference image is collected by the area array camera, and the interference image is demodulated by the computer.

2. A three-dimensional line imaging method, using the three-dimensional line imaging device according to claim 1, characterized in that The steps include: Step S1: Determine the relationship between chromatic aberration and depth; first, set the spectral measurement range to AE, then divide the spectral measurement range AE into four equal parts, namely AB spectral segment, BC spectral segment, CD spectral segment, and DE spectral segment, and AB = BC = CD = DE; wherein, the spectral positions corresponding to the depths of AB, BC, CD, and DE are set to λ A -λ B ,λ B -λ C ,λ C -λ D ,λ D -λ E ; Step S2: Determine the positions of the four reference arms; the depth position reference points of the reflectors are represented by A, B, C, and D in sequence; first, determine the position of the first reflector in the first reference arm, select a debugging reflector, and place the debugging reflector at a depth position A1 below the chromatic aberration lens, then move the positions of the first filter, the third lens, and the first reflector until the reference light reflected by the first reflector and the sample light reflected by the debugging reflector reach the same optical path; then, determine the position of the second reflector in the second reference arm, place the debugging reflector at a depth position B1 below the chromatic aberration lens, then move the positions of the second filter, the fourth lens, and the second reflector until the reference light reflected by the second reflector and the sample light reflected by the debugging reflector reach the same optical path. ; Afterwards, determine the position of the third reflector in the third reference arm, place the debugging reflector at a depth position C1 below the chromatic aberration lens, and then move the positions of the third filter, the fifth lens, and the third reflector until the reference light reflected by the third reflector and the sample light reflected by the debugging reflector reach the same optical path; finally, determine the position of the fourth reflector in the fourth reference arm, place the debugging reflector at a depth position D1 below the chromatic aberration lens, and then move the positions of the fourth filter, the sixth lens, and the fourth reflector until the reference light reflected by the fourth reflector and the sample light reflected by the debugging reflector reach the same optical path; at this time, the reflector depth position reference points A, B, C, and D are offset relative to the reflector depth position setting points A1, B1, C1, and D1; Step S3: Block the sample light and obtain the interference spectra of four reference lights, which are respectively recorded as the first reference light, the second reference light, the third reference light, and the fourth reference light; since the transmission spectrum of the first reference light only overlaps with the transmission spectrum of the second reference light, the reflected first reference light only interferes with the reflected second reference light, and the interference spectrum appears in the overlapping area of ​​the two transmission spectra; similarly, the interference spectrum of the reflected second reference light and the reflected third reference light appears in the overlapping area of ​​the two transmission spectra, and the interference spectrum of the reflected third reference light and the reflected fourth reference light appears in the overlapping area of ​​the two transmission spectra. The optical path difference between the second and third reflectors relative to the first reflector is D21, the optical path difference between the third and third reflectors relative to the second reflector is D32, and the optical path difference between the fourth and fourth reflectors relative to the third reflector is D43. Therefore, the offset of the first reference arm is 0, the offset of the second reference arm relative to the first reference arm is D21, the offset of the third reference arm relative to the first reference arm is D21+D32, and the offset of the fourth reference arm relative to the first reference arm is D21+D32+D43. Step S4: Set the line profile distribution on the sample as H(x), where x represents the coordinates of different points on the sample on the linear detection light; set the interference image obtained by the computer as I(k i ,x),I(k i , x) represents the interference spectrum formed by the sample light and the reference light reflected by the point with coordinate x on the sample line; where k i is the horizontal coordinate of the interference image, k i represents the wave number corresponding to the i-th pixel in the lateral direction of the spectrum, and i=1, 2, 3, etc.; for the interference image I(k i , x) is processed separately to obtain the height of the point; assuming the depth of the sample is H1, according to the envelope of the interference spectrum, the horizontal coordinate of the maximum value of the interference spectrum is determined to be λ0, and λ0 is located at λ A and λ B Based on the relationship between wavelength and depth in chromatic aberration technology, it is determined that the depth H1 of the sample is within the AB spectral band. Therefore, it can be determined that the interference spectrum is the interference spectrum of the sample light and the first reference light. Then, the relative depth obtained by demodulating the interference spectrum is set as L1. The depth H1 of the sample is equal to the relative depth L1 plus the offset of the first reference arm. Step S5: Assuming that the depth of the sample is H2, the interference spectrum appears in the interval where the transmission spectrum of the first reference arm and the second reference arm overlap, and then according to the envelope of the interference spectrum, the wavelength λ1 corresponding to the maximum value of the interference spectrum is determined. λ1 is located at λ A and λ C According to the relationship between wavelength and depth in the chromatic aberration technology, it is determined that the depth H2 of the sample is within the AC spectral band; since the sample light interferes with the first reference light and the second reference light respectively, two peaks will appear in the interference spectrum after fast Fourier transform; since the depth H2 of the sample is far from the equal optical path point of the first reflector and close to the equal optical path point of the second reflector, the frequency of the interference spectrum between the sample light and the first reference light is higher, and the frequency of the interference spectrum between the sample light and the second reference light is lower; then the interference spectrum between the sample light and the first reference light is obtained by high-pass filtering, and the relative depth demodulated by the interference spectrum is set to L2, then the depth H2 of the sample is equal to the relative depth L2 plus the offset of the first reference arm; Step S6: Assuming the depth of the sample is H4, determine the wavelength λ2 corresponding to the maximum value of the interference spectrum according to the envelope of the interference spectrum. λ2 is located at λ D and λ E According to the relationship between wavelength and depth in the chromatic aberration technique, the depth H4 of the sample is determined to be within the DE spectral band. Then, the relative depth obtained by demodulating the interference spectrum is set as L4. The depth H4 of the sample is equal to the relative depth L4 plus the offset of the fourth reference arm. Step S7: Similarly, the depth of the sample at any point between the spectral measurement range AE is obtained, and then the line profile distribution of the sample is obtained, and finally the three-dimensional line imaging measurement of the moving object is realized.

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