A scanning multiplexed optical coherence measurement system

Abstract

The application provides a scanning multiplexed optical coherence measurement system, which is suitable for welding OCT scenes or other OCT application fields. The system comprises a processing module, a control module, an acquisition module and an OCT optical path module. The OCT optical path module comprises an OCT laser, an interference module, a polarization controller, a sample arm optical path module and an optical-electric conversion module. The sample arm optical path module comprises a scanning mirror and a calibration component.

Description

Technical Field

[0001] This invention relates to the field of optical coherent measurement technology, and in particular to an optical coherent measurement system that uses a multiplexed scanner to acquire calibration signals. Background Technology

[0002] Optical coherence measurement (OCT) technology utilizes the interference relationship between reference light and the sample's reflected light to obtain depth information of the sample under test. It features non-contact measurement, high measurement speed, and the ability to perform tomographic or surface measurements. Existing OCT systems typically require altering the incident position of the OCT measurement light using scanning mirrors, galvanometers, MEMS scanners, or other scanning devices to obtain multiple A-lines and form B-scan or C-scan images. It has already been applied in ophthalmology, dermatology, dentistry, endoscopy, laser welding, and industrial inspection.

[0003] During optical coherent measurement, the output characteristics of the light source, the spectral sampling relationship, the scanning sequence, and the optical path state may change with device temperature, operating time, environmental variations, and device aging, causing deviations between the acquired interference signal and the actual wavenumber or optical path length. To obtain more accurate depth position and measurement results, the system typically needs to acquire a calibration interference signal and generate interpolation correction parameters or other correction parameters based on the calibration interference signal.

[0004] Existing solutions typically generate calibration signals through a separate MZI module, an additional reflective optical path, or a dedicated calibration optical path, and are equipped with photodetectors, data acquisition channels, or dedicated acquisition cards. These solutions increase the number of system components, the complexity of optical path assembly and adjustment, and equipment costs. In space-constrained systems such as ophthalmology, additional calibration optical paths can also complicate the optomechanical structure and increase size. In laser welding and other industrial inspection scenarios, the inspection head needs to move at high speed with the motion mechanism; additional components further increase equipment weight and vibration resistance requirements.

[0005] Therefore, it is necessary to propose a scanning multiplexed optical coherent measurement system. By multiplexing the scanning mirror in the sample arm, the OCT measurement light is incident on the sample under test in the measurement state and deviates from the OCT measurement light path and incident on the calibration component in the calibration state. Thus, the calibration signal is obtained by using a shared light source, interference, detection and acquisition link, and it is applicable to different types and different application scenarios of optical coherent measurement systems. Summary of the Invention

[0006] The present invention aims to at least solve the technical problems existing in the prior art, and proposes a scanning multiplexed optical coherent measurement system.

[0007] To achieve the above objectives, the present invention provides a scanning multiplexed optical coherent measurement system, comprising a processing module, a control module, an acquisition module, and an OCT optical path module; the OCT optical path module includes an OCT laser, an interferometer module, a polarization controller, a sample arm optical path module, and a photoelectric conversion module; the sample arm optical path module includes a scanning mirror and a calibration component; the calibration component includes a calibration reflector; the scanning mirror has a measurement state and a calibration state; adjusting the polarization controller state can change the intensity of the OCT measurement signal S1 and the intensity of the calibration signal K1; in the measurement state, the scanning mirror causes the OCT measurement light to be incident. When the sample is tested, the returned light interferes with the reference arm light to obtain the OCT measurement signal S1. In the calibration state, the scanning mirror deviates the OCT measurement light from the OCT measurement optical path and incident on the calibration component. The returned light from the calibration component interferes with the reference arm light to obtain the calibration signal K1. The processing module generates interpolation correction parameters based on the calibration signal K1 and uses the interpolation correction parameters to interpolate and correct the OCT measurement signal S1. The measurement state and the calibration state share the OCT laser, interference module, polarization controller, sample arm optical path module, photoelectric conversion module, acquisition module, and processing module.

[0008] In a preferred embodiment of the present invention, the processing module is connected to the control module and the acquisition module respectively; the interference module is connected to the OCT laser, the polarization controller and the photoelectric conversion module respectively; the polarization controller is disposed between the interference module and the sample arm optical path module; the photoelectric conversion module is connected to the interference module and the acquisition module respectively; the sample arm optical path module is used to incident the OCT measurement light onto the sample to be tested and to receive the sample arm return light returned by the sample to be tested.

[0009] In a preferred embodiment of the present invention, the control module is used to generate and / or receive timing control signals required for system operation according to system control instructions output by the processing module; the timing control signals include a first timing signal T1, a second timing signal T2, and a third timing signal T3; the first timing signal T1 is used to synchronize the working state of the OCT laser; the second timing signal T2 is used to control the sample arm optical path module to switch between measurement state and calibration state; the third timing signal T3 is used to trigger the acquisition module to perform data acquisition.

[0010] In a preferred embodiment of the present invention, the calibration component includes a calibration reflector, which includes one or more sub-reflector units; the calibration reflector is a mirror, a hollow mirror, a right-angle prism, a corner prism, a glass plate, a metal plate, or other devices and / or modules with beam reflection capability; when the calibration reflector includes multiple sub-reflector units, different sub-reflector units have different optical path differences with the scanning mirror to form multiple calibration signals K1 of different frequencies; the processing module stores the pre-calibrated optical path difference values ​​corresponding to different sub-reflector units, and performs interpolation correction and depth correction on the OCT measurement signal S1 according to the pre-calibrated optical path difference values ​​and multiple calibration signals K1 of different frequencies.

[0011] In a preferred embodiment of the present invention, the calibration component includes an optical path refraction element disposed between the scanning mirror and the calibration reflector; in the calibration state, the scanning mirror causes the OCT measurement light to deviate from the OCT measurement optical path and be incident on the optical path refraction element, and the optical path refraction element changes the propagation direction of the calibration optical path, so that the calibration light is incident on the calibration reflector along the folded calibration optical path.

[0012] In a preferred embodiment of the present invention, the optical path difference between the scanning mirror and the calibration reflector is: The optical path difference between the scanning mirror and the upper surface or interface of the sample to be tested is The optical path difference between the scanning mirror and the zero optical path difference position of the OCT system is The zero optical path difference position of the OCT system is located above the upper surface of the sample or the interface to be measured, and Less than 10% of the maximum imaging depth of the OCT system, and meets the following requirements: .

[0013] In a preferred embodiment of the present invention, the optical path difference between the scanning mirror and the calibration reflector The optical path difference is less than the optical path difference between the scanning mirror and the zero optical path difference position of the OCT system. and satisfy as well as The calibration signal K1 generated by the calibration reflector and the OCT measurement signal S1 generated by the upper surface or interface of the sample under test are located on both sides of the zero optical path difference position of the OCT system.

[0014] In a preferred embodiment of the present invention, the sample arm optical path module is an anterior segment OCT sample arm optical path module, including a collimator, a scanning mirror, a calibration component, a first lens group, a first dichroic mirror, and a camera module; the calibration component includes a calibration reflector; the collimator, scanning mirror, first dichroic mirror, and first lens group are sequentially optically connected, the camera module is optically connected to the first dichroic mirror, and the calibration reflector is optically connected to the scanning mirror; in the measurement state, the scanning mirror causes the OCT measurement light to be incident on the sample to be measured through the first dichroic mirror and the first lens group; in the calibration state, the scanning mirror causes the OCT measurement light to deviate from the OCT measurement optical path and be incident on the calibration reflector.

[0015] In a preferred embodiment of the present invention, the sample arm optical path module is a posterior segment OCT sample arm optical path module, comprising a collimator, a scanning mirror, a calibration component, a first lens group, a second lens group, an electric displacement device, a first dichroic mirror, a second dichroic mirror, a camera module, a third lens group, and a fixation screen; the calibration component includes a calibration reflector; the collimator, scanning mirror, first lens group, first dichroic mirror, and second lens group are sequentially optically connected; the camera module is optically connected to the first dichroic mirror; and the fixation screen, third lens group, second dichroic mirror, first dichroic mirror, and second lens group are sequentially optically connected. The calibration reflector is connected to the scanning mirror optical path, and the electric displacement device is mechanically connected to the second lens group. The first and second lens groups form a 4F optical path, which is used to make the plane where the scanning mirror is located and the position of the pupil of the eye to be tested form a conjugate relationship. The electric displacement device is used to drive the second lens group to move along the optical axis, so that the OCT optical path and the fixation optical path can be focused simultaneously. In the measurement state, the scanning mirror causes the OCT measurement light to be incident on the sample to be tested through the first lens group, the first dichroic mirror, and the second lens group. In the calibration state, the scanning mirror causes the OCT measurement light to deviate from the OCT measurement optical path and be incident on the calibration reflector.

[0016] In a preferred embodiment of the present invention, the sample arm optical path module is a laser welding OCT sample arm optical path module, including a collimator, a zoom lens, a scanning lens, a calibration component, a dichroic mirror one, a dichroic mirror two, a welding unit, a welding light collimator, a scanning unit, and an objective lens; the calibration component includes a calibration reflector and an optical path refraction element; the collimator, zoom lens, scanning lens, dichroic mirror one, scanning unit, and objective lens are sequentially optically connected to form an OCT measurement optical path; the welding unit, welding light collimator, dichroic mirror two, dichroic mirror one, scanning unit, and objective lens are sequentially optically connected to form a welding optical path; the optical path refraction element is disposed between the scanning lens and the calibration reflector; in the calibration state, the scanning lens causes the OCT measurement light to deviate from the OCT measurement optical path and be incident on the optical path refraction element, and the optical path refraction element changes the propagation direction of the calibration light path, so that the calibration light is incident on the calibration reflector.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects:

[0018] (1) By switching the same scanning mirror between measurement and calibration states, the two states share the OCT laser, interference module, polarization controller, sample arm optical path module, photoelectric conversion module, acquisition module and processing module, which can reduce the independent calibration optical path and its supporting devices, reduce system cost, reduce system weight and assembly complexity; ordinary single-channel data acquisition card can be used instead of OCT dedicated data acquisition card, which can significantly reduce the cost of data acquisition card.

[0019] (2) When the calibration reflector includes multiple sub-reflection units, multiple calibration interference signals of different frequencies can be formed; combined with the pre-calibrated and stored different optical path difference values, the OCT system can be interpolated and corrected for depth. This helps the OCT system ensure the accuracy of depth measurement in complex working environments.

[0020] (3) The optical path folding element changes the propagation direction of the calibration optical path, enabling the calibration components to be arranged in a folded spatial manner, which is beneficial to reducing the space occupation of the system and to realizing an integrated OCT system.

[0021] (4) By setting the calibration signal K1 and the OCT measurement signal S1 to be located on both sides of the zero optical path difference position of the OCT system, the present invention can reduce the optical path difference of the calibration optical path, thereby reducing the overall system size. Attached Figure Description

[0022] The embodiments of the present invention will be described in conjunction with the following accompanying drawings, which will provide a clearer understanding of the technical solutions of the present invention, wherein:

[0023] Figure 1 This is a schematic diagram of an OCT device for scanning multiplexing according to the present invention.

[0024] Figure 2 These are schematic diagrams of the interference module of the present invention. (a) Schematic diagram of a low-cost interference module, (b) Schematic diagram of a high-sensitivity interference module.

[0025] Figure 3 This is a schematic diagram of the optical path module of the anterior segment OCT sample arm according to the present invention.

[0026] Figure 4 This is a schematic diagram of the optical path module of the posterior segment OCT sample arm according to the present invention.

[0027] Figure 5 This is a schematic diagram of the optical path module for laser welding OCT sample arm according to the present invention.

[0028] Reference numerals: 1 for processing module, 2 for control module, 3 for acquisition module, 4 for OCT optical path module; where 41 is OCT laser, 42 is interference module, 43 is polarization controller, 44 is sample arm optical path module, 45 is photoelectric conversion module, 421 is first fiber coupler, 422 is equal-splitting fiber coupler, 423 is attenuator, 424 is optical path difference delay line, 425 is fiber circulator; 46 is collimator, 461 is zoom lens, 47 is scanning mirror, 48 is calibration reflector, 491 is lens group one, 492 is lens group two, 493 is electric displacement device, 501 is dichroic mirror one, 52 is camera module, 53 is dichroic mirror two, 54 is lens group three, 55 is fixed screen, 61 is welding unit, 62 is welding optical collimator, 63 is scanning unit, 64 is objective lens, and 65 is optical path folding element. T1, T2, and T3 are timing signals used for OCT laser synchronization, sample arm optical path module state switching, and data acquisition triggering. Detailed Implementation

[0029] The embodiments of the present invention are described in detail below. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0030] Example 1

[0031] like Figure 1 As shown, this embodiment provides an optical coherence measurement system, which includes a processing module 1, a control module 2, an acquisition module 3, and an OCT optical path module 4.

[0032] The processing module 1 is electrically connected to both the control module 2 and the acquisition module 3. The processing module 1 sends system control commands to the control module 2 and receives acquisition data output from the acquisition module 3, processing the acquired data to obtain measurement results for the sample under test. The measurement results may include interface location, tomographic images, thickness parameters, length parameters, keyhole depth, weld penetration parameters, or imaging data.

[0033] The control module 2 is used to generate and / or receive timing control signals required for system operation based on system control commands output by the processing module 1. The timing control signals include a first timing signal T1, a second timing signal T2, and a third timing signal T3. The first timing signal T1 is used to synchronize the operating state of the OCT laser 41 in the OCT optical path module 4; the second timing signal T2 is used to control the switching of the OCT optical path module 4 between measurement and calibration states; and the third timing signal T3 is used to trigger the acquisition module 3 to acquire data. Thus, the control module 2 enables the light output and optical path state switching of the OCT optical path module 4 and the data acquisition of the acquisition module 3 to remain synchronized.

[0034] The acquisition module 3 is used to acquire the electrical signal output by the OCT optical path module 4 under the triggering of the third timing signal T3, and send the acquired data to the processing module 1.

[0035] The OCT optical path module 4 can be one or more of swept frequency OCT, spectral domain OCT, and time domain OCT.

[0036] The OCT optical path module 4 includes an OCT laser 41, an interference module 42, a polarization controller 43, a sample arm optical path module 44, and a photoelectric conversion module 45. The OCT laser 41 is optically connected to the interference module 42 and is used to output OCT detection light to the interference module 42. The OCT laser 41 can be a swept frequency light source, a broadband low-coherence light source, or other light sources suitable for optical coherence measurement.

[0037] The interference module 42 is connected to the OCT laser 41, the polarization controller 43, and the photoelectric conversion module 45, respectively. The interference module 42 is used to distribute the OCT detection light output by the OCT laser 41 to the reference arm and the sample arm, and to cause the light returned from the reference arm to interfere with the light returned from the sample arm, forming an interference light signal.

[0038] The polarization controller 43 is disposed between the interference module 42 and the sample arm optical path module 44. The polarization controller 43 is used to adjust the polarization state of the light entering the sample arm optical path module 44, or to adjust the polarization state of the light returning from the sample arm optical path module 44 to the interference module 42, so as to improve the contrast of the interference light signal.

[0039] The photoelectric conversion module 45 is connected to the interference module 42 and the acquisition module 3. The photoelectric conversion module 45 receives the interference light signal output by the interference module 42 and converts the interference light signal into an electrical signal before outputting it to the acquisition module 3. For frequency-sweep OCT and time-domain OCT systems, the photoelectric conversion module 45 is preferably a photoelectric balanced detector; for spectral-domain OCT systems, the photoelectric conversion module 45 is preferably a spectrometer based on a linear array camera.

[0040] In one embodiment, the sample arm optical path module 44 includes a scanning mirror 47 and a calibration component, the calibration component including a calibration reflector 48. When the system is in measurement mode, the scanning mirror 47 directs the OCT measurement light onto the sample to be measured. When the system is in calibration mode, the scanning mirror 47 deflects the OCT measurement light off the OCT measurement optical path and directs it onto the calibration reflector 48. The light returned by the calibration reflector 48 is then returned to the interference module 42 via the sample arm optical path module 44 and the polarization controller 43. Thus, this embodiment, through the cooperation between the processing module 1, the control module 2, the acquisition module 3, and the OCT optical path module, enables the system to acquire the OCT measurement signal S1 of the sample to be measured in measurement mode and to acquire the calibration signal K1 in calibration mode. The processing module 1 can generate interpolation parameters based on the calibration signal K1 and perform interpolation correction on the OCT measurement signal S1.

[0041] The advantage of this embodiment is that the measurement state and the calibration state can share the same devices such as the OCT laser 41, interference module 42, polarization controller 43, sample arm optical path module 44, photoelectric conversion module 45, acquisition module 3 and processing module 1. It does not require a separate complete MZI module, additional photodetector or additional data acquisition channel for the calibration function, thereby significantly reducing system cost and structural complexity.

[0042] Conventional swept-frequency OCT systems typically require a separate MZI module to generate a k-space calibration signal for interpolation correction, along with additional photodetectors and dedicated OCT data acquisition cards, so that each A-line can self-correct based on its corresponding real-time calibration signal. While this approach achieves real-time correction, it increases system hardware costs, optical path complexity, and acquisition system requirements.

[0043] The core idea of ​​this embodiment is that it does not require each A-line to acquire its corresponding calibration signal and complete self-correction in real time. Instead, a calibration signal K1 can be acquired once during a B-scan, a C-scan, a preset number of A-lines, a preset time interval, a scan idle interval, or before or after measurement. Interpolation correction parameters are then generated based on these calibration signals K1, and these parameters are used to interpolate and correct the previously or subsequently acquired OCT measurement signals S1. For high-speed OCT lasers 41, such as sweep light sources with A-line frequencies greater than 10kHz, their output spectral state typically exhibits good relative stability within approximately 0.1s during a B-scan or approximately 5s during a C-scan. Therefore, the interpolation correction parameters acquired earlier or later can be used to effectively correct the OCT measurement signals S1. Thus, this embodiment can maintain the ability to correct the OCT measurement signals S1 while reducing the complexity of the optical path and the need for dedicated acquisition hardware.

[0044] Example 2

[0045] This embodiment is a further supplementary description of the interference module 42 based on Embodiment 1. The contents that are the same as those in Embodiment 1 will not be repeated.

[0046] In one embodiment, the interference module 42 can employ a low-cost approach, characterized by forming interference between the reference arm beam and the sample arm beam while minimizing the number of optical components and system cost. The interference module 42 may comprise only a first fiber coupler 421 and a split fiber coupler 422. Figure 2As shown in (a), the OCT laser 41 is connected to the first port of the first fiber coupler 421 via an optical fiber. The third port of the first fiber coupler 421 is connected to the second port of the split fiber coupler 422 via an optical fiber. The fourth port of the first fiber coupler 421 is connected to the first port of the split fiber coupler 422 via an optical fiber. The second port of the first fiber coupler 421 is connected to the polarization controller 43 and the sample arm optical path module 44. If the laser power is too high, an attenuator 423 can be added between the third port of the first fiber coupler 421 and the second port of the split fiber coupler 422. If a wide range of optical path difference adjustment is required, an optical path difference delay line 424 can be added between the third port of the first fiber coupler 421 and the second port of the split fiber coupler 422. The first fiber coupler 421 is used to split the incident light from the OCT laser 41 into a sample arm beam and a reference arm beam. The propagation path of the sample arm beam is as follows: after exiting from the second port of the first fiber coupler 421, it passes sequentially through the polarization controller 43 and the sample arm optical path module 44, finally incident on the sample under test. After being back-reflected and / or scattered by the sample, the beam passes sequentially through the sample arm optical path module 44 and the polarization controller 43, and then returns to the second port of the first fiber coupler 421. The sample return light then exits through the fourth port of the first fiber coupler 421, finally entering the first port of the split fiber coupler 422. The propagation path of the reference arm beam is as follows: after exiting from the third port of the first fiber coupler 421, it passes through the attenuator 423 and the optical path difference delay line 424, and then directly enters the second port of the split fiber coupler 422. The sample return light entering the split fiber coupler 422 and the reference arm beam interfere here. The output end of the split fiber coupler 422 is connected to the photoelectric conversion module 45. This low-cost interference module 42 is suitable for cases where the reflectivity of the sample under test is relatively low, such as less than 1%, preferably less than 0.1%. Suitable scenarios include biological samples such as endoscopic OCT imaging, ophthalmic OCT imaging, and skin OCT imaging. In this case, the light power returned to the OCT laser 41 from the sample will be very weak, with minimal negative impact on the laser and no impact on normal OCT imaging. In another embodiment, the interference module 42 can adopt a high-sensitivity interference module scheme, characterized by maximizing the signal-to-noise ratio or detection sensitivity of the interference signal. For example... Figure 2As shown in (b), the OCT laser 41 is connected to the first port of the first fiber coupler 421 via an optical fiber. The third port of the first fiber coupler 421 is connected to the first port of the split fiber coupler 422 via an optical fiber after passing through the attenuator 423 and the optical path difference delay line 424. The second port of the first fiber coupler 421 is connected to the first port of the fiber circulator 425 via an optical fiber. The second port of the fiber circulator 425 is connected to the polarization controller 43 and the sample arm optical path module 44 in sequence. The third port of the fiber circulator 425 is connected to the second port of the split fiber coupler 422 via an optical fiber.

[0047] The first fiber coupler 421 is used to split the incident light from the OCT laser 41 into a sample arm beam and a reference arm beam. The propagation path of the sample arm beam is as follows: after exiting from the second port of the first fiber coupler 421, it passes sequentially through the first port of the fiber circulator 425, the second port of the fiber circulator 425, the polarization controller 43, and the sample arm optical path module 44, finally incident on the sample to be tested. After being back-reflected and / or scattered by the sample, the beam passes sequentially through the sample arm optical path module 44 and the polarization controller 43, and then returns to the second port of the fiber circulator 425. The sample return beam then exits through the third port of the fiber circulator 425 and finally enters the second port of the split fiber coupler 422. The propagation path of the reference arm beam is as follows: after exiting from the third port of the first fiber coupler 421, it passes through the attenuator 423 and the optical path difference delay line 424, and then directly enters the first port of the split fiber coupler 422. The sample return beam and the reference arm beam interfere with each other upon entering the split fiber coupler 422. The output of the evenly distributed fiber coupler 422 is connected to the photoelectric conversion module 45.

[0048] This high-sensitivity interference module 42 is suitable for systems that require maximizing the signal-to-noise ratio or sensitivity of the OCT system. The use of a fiber optic circulator 425 maximizes the transmission efficiency of the sample return light entering the photoelectric conversion module 45. Suitable applications include endoscopic OCT systems, ophthalmic OCT systems, and laser welding OCT detection systems. Another advantage of using the fiber optic circulator 425 is that it prevents the sample return light from entering the OCT laser 41, which is crucial in the field of laser welding OCT detection. In laser welding OCT detection systems, the sample is the interface between metal and air, and its reflectivity is typically several times or even tens of times greater than that between different layers within biological tissue.

[0049] Example 3

[0050] This embodiment is a further supplementary description based on Embodiment 1 and Embodiment 2. The system framework and basic functions of the interference module that are the same as those in the previous embodiments will not be repeated.

[0051] Figure 3 An anterior segment OCT system based on this invention is demonstrated. The sample arm optical path module 44 includes a collimator 46, a scanning mirror 47, a calibration reflector 48, a lens group 491, a dichroic mirror 501, and a camera module 52. The path of the OCT measurement light in the OCT measurement optical path module 44 is as follows: after exiting the collimator 46, it passes sequentially through the scanning mirror 47, the dichroic mirror 501, and the lens group 491, finally focusing on the sample or the eye being tested. The path of the camera-assisted function in the sample arm optical path module 44 is as follows: the sample return light passes sequentially through the lens group 491 and the dichroic mirror 501, finally being imaged onto the camera module 52.

[0052] When the parameters of the sample to be tested are determined and the relationship between the zero optical path difference position of the OCT system and the imaging focal plane is matched, it is not necessary to add a zoom lens 461 after the collimator 46.

[0053] In OCT imaging mode, the scanning mirror 47 scans normally, so that the OCT measurement light is incident on the cornea, anterior chamber, lens or related sample interface through the anterior segment measurement light path. The light returned by the eyeball or sample forms an interference light signal with the reference arm light, which is then acquired by the acquisition module 3 to obtain the OCT measurement signal S1.

[0054] In the calibration state, the scanning mirror 47 is deflected to the calibration angle, causing the OCT measurement light to deviate from the anterior segment measurement light path and be incident on the calibration reflector 48. The light returned by the calibration reflector 48 forms a calibration interference signal with the reference arm light, which is then acquired by the acquisition module 3 to obtain the calibration signal K1.

[0055] Processing module 1 generates interpolation correction parameters based on calibration signal K1 and performs OCT interpolation correction on previously or subsequently acquired OCT measurement signals S1.

[0056] The optical path difference between the scanning mirror 47 and the calibration reflector 48 is The optical path difference between the scanning mirror 47 and the upper surface or interface of the sample to be tested is... The optical path difference between the scanning mirror 47 and the zero optical path difference position of the OCT system is... ;

[0057] In one implementation, the zero optical path difference position of the OCT system is located above the upper surface of the sample or the interface to be measured, so that the entire tomographic image of the sample is on the same side after FFT, and there is no image flipping about the zero optical path difference position; the optical path difference between the zero optical path difference position of the OCT system and the upper surface of the sample or the interface to be measured... Preferably, the depth is less than 10% of the maximum imaging depth of the OCT system; the above parameters satisfy the following relationship: .

[0058] In another implementation, to minimize the mechanical dimensions of the sample arm optical path module, the optical path difference between the scanning mirror 47 and the calibration reflector 48 can be minimized. The optical path difference is smaller than that between the scanning mirror 47 and the zero optical path difference position of the OCT system. The above parameters satisfy: and satisfy .

[0059] Therefore, the calibration signal K1 generated by the calibration reflector 48 and the OCT measurement signal S1 generated by the upper surface of the sample or the interface to be measured are located on both sides of the zero optical path difference position of the OCT system.

[0060] The calibration component includes a calibration reflector 48, which comprises one or more sub-reflector units. The calibration reflector 48 can be a mirror, hollow mirror, right-angle prism, cornerstone prism, glass plate, metal plate, or other device and / or module with beam reflection capability. When the calibration reflector 48 comprises multiple sub-reflector units, different sub-reflector units have different optical path differences with the scanning mirror 47, forming multiple calibration signals K1 of different frequencies. The processing module 1 stores pre-calibrated optical path difference values ​​corresponding to different sub-reflector units and performs interpolation correction and depth correction on the OCT measurement signal S1 based on the pre-calibrated optical path difference values ​​and the multiple calibration signals K1 of different frequencies. Depth correction refers to the processing module 1 determining the depth position or depth mapping relationship corresponding to the calibration signal K1 based on the pre-calibrated optical path difference values, and correcting the depth relationship of the OCT measurement signal S1 accordingly.

[0061] In one embodiment, the optical path difference values ​​corresponding to different sub-reflection units can be pre-calibrated before the system leaves the factory and stored in the processing module 1. Thus, when environmental temperature, operating time, or other factors cause changes in the output state of the OCT laser 41—for example, changes in the bandwidth, start wavelength, or end wavelength of the output spectrum—the processing module 1 can still accurately correct the OCT measurement signal S1 based on the known optical path difference values ​​corresponding to different sub-reflection units, thereby obtaining accurate depth relationships in the OCT image.

[0062] This embodiment can be used to obtain anterior segment OCT images, and can further extract ocular biological parameters such as corneal thickness, anterior chamber depth, lens thickness, and axial length from the anterior segment OCT images.

[0063] Example 4

[0064] This embodiment is a further supplementary description based on Embodiment 1, Embodiment 2 and Embodiment 3. The same system framework, basic functions of the interference module and optical path difference constraint conditions between the scanning mirror 47 and the calibration reflector 48 as in the aforementioned embodiments will not be repeated.

[0065] Figure 4 An OCT system for the posterior segment of the eye based on this invention is demonstrated. The sample arm optical path module 44 includes a collimator 46, a scanning mirror 47, a calibration reflector 48, a first lens group 491, a second lens group 492, an electric displacement device 493, a first dichroic mirror 501, a second dichroic mirror 53, a camera module 52, a third lens group 54, and a fixation screen 55. The OCT measurement light in the sample arm optical path module 44 exits from the collimator 46, passes sequentially through the scanning mirror 47, the first lens group 491, the first dichroic mirror 501, and the second lens group 492, and finally enters the posterior segment region of the sample or the eye to be tested. The first dichroic mirror 501 is positioned at the convergence point of the OCT measurement optical path and the camera optical path. The second dichroic mirror 53 is positioned at the convergence point of the fixation optical path and the camera optical path. The camera-assisted function in the sample arm optical path module 44 follows a path where the light returning from the eye passes sequentially through lens group two 492, dichroic mirror one 501, and is finally imaged onto the camera module 52. The fixation-assisted function in the sample arm optical path module 44 follows a path where the fixation signal emitted from the fixation screen 55 passes sequentially through lens group three 54, dichroic mirror two 53, dichroic mirror one 501, and lens group two 492, and is finally imaged onto the eye under test. Thus, the eye under test can obtain a fixation target through the fixation screen 55, facilitating eye position stability during posterior segment OCT imaging.

[0066] The lens group 491 and lens group 492 form a 4F optical path. This 4F optical path is used to establish a conjugate relationship between the scanning position of the scanning mirror 47 and the pupil position of the eye being tested. This allows the OCT measurement light to enter the eye in a manner close to rotating around the center of the pupil when the scanning mirror 47 rotates, thereby reducing the lateral offset of the beam at the pupil during scanning. Specifically, one focal plane of lens group 491 is located in the plane of the rotation axis of the scanning mirror 47, and one focal plane of lens group 492 is located in the plane of the pupil of the eye being tested; alternatively, lens group 491 and lens group 492 together form a relay imaging relationship between the scanning mirror 47 and the pupil of the eye being tested. Thus, the plane of the scanning mirror 47 can be relayed to the pupil position of the eye being tested, ensuring a stable entry of the scanning beam during posterior segment OCT imaging into the pupil.

[0067] The electric displacement device 493 is connected to the second lens group 492 and is used to drive the second lens group 492 to move back and forth along the optical axis of the sample arm optical path, thereby changing the imaging focal point position of the sample arm optical path module 44. Because different human eyes have differences in refractive power (myopia, hyperopia), if the imaging focal point of the posterior segment OCT system remains fixed, the OCT measurement light may not be accurately focused on the retina or related interfaces of the fundus, resulting in a decrease in OCT signal intensity or image quality. In this embodiment, by moving the second lens group 492 through the electric displacement device 493, the differences in refractive power between different human eyes can be compensated, allowing the OCT measurement light to be flexibly focused on the desired fundus position.

[0068] Since both the fixation imaging light and the OCT measurement light enter the eye under test through lens group two 492, when the electric displacement device 493 drives lens group two 492 to move back and forth, the imaging focus of the OCT optical path and the fixation focus of the fixation optical path can change simultaneously. In other words, the movement of lens group two 492 can not only adjust the focusing state of the OCT measurement light at the fundus, but also simultaneously adjust the imaging state of the fixation screen 55 in the eye under test. Thus, when focusing for different refractive errors of the human eye, it is not necessary to set up independent focusing mechanisms for the OCT optical path and the fixation optical path separately, thereby reducing system complexity and enabling the OCT measurement optical path and the fixation optical path to be focused and adjusted simultaneously.

[0069] In OCT imaging mode, the scanning mirror 47 scans normally, so that the OCT measurement light enters the fundus, retina or related sample interface through the measurement light path of the posterior segment of the eye. The light returned from the eyeball and the reference arm light form an interference light signal, which is acquired by the acquisition module 3 to obtain the OCT measurement signal S1.

[0070] In the calibration state, the scanning mirror 47 is deflected to the calibration angle, causing the OCT measurement light to deviate from the posterior segment measurement light path and be incident on the calibration reflector 48. The light returned by the calibration reflector 48 forms a calibration interference signal with the reference arm light, which is then acquired by the acquisition module 3 to obtain the calibration signal K1.

[0071] Processing module 1 generates interpolation correction parameters based on calibration signal K1 and performs OCT interpolation correction on previously or subsequently acquired OCT measurement signals S1. The interpolation correction parameters may include one or more of the following: time-wavenumber mapping relationship, pixel-wavenumber mapping relationship, optical path delay correction parameters, or scanning nonlinearity correction parameters.

[0072] In this embodiment, the optical path relationship between the scanning mirror 47, the calibration reflector 48, the zero optical path difference position of the OCT system, and the interface of the fundus to be tested can be referred to in Embodiment 3 regarding... , and The description will not be repeated here.

[0073] This embodiment can be used to obtain OCT images of the posterior segment of the eye, and can further extract the location of the retinal interface, axial length, axial length of the peripheral region of the eyeball, fundus surface morphology, or other ocular biological parameters from the OCT images of the posterior segment of the eye.

[0074] Example 5

[0075] This embodiment is a further supplementary description based on Embodiment 1, Embodiment 2 and Embodiment 3. The same system framework, basic functions of the interference module and optical path difference constraint conditions between the scanning mirror 47 and the calibration reflector 48 as in the aforementioned embodiments will not be repeated.

[0076] Figure 5 A laser welding OCT inspection system based on this invention is demonstrated. The sample arm optical path module 44 includes a collimator 46, a zoom lens 461, a scanning mirror 47, a calibration reflector 48, a dichroic mirror 501, a camera module 52, a dichroic mirror 53, a welding unit 61, a welding light collimator 62, a scanning unit 63, an objective lens 64, and an optical path refraction element 65. The OCT measurement light in the sample arm optical path module 44 exits from the collimator 46, passes sequentially through the zoom lens 461, the scanning mirror 47, the dichroic mirror 501, the scanning unit 63, and the objective lens 64, and finally enters the sample area to be welded. The welding light in the sample arm optical path module 44 exits from the welding unit 61, is collimated by the welding light collimator 62, then passes sequentially through the dichroic mirror 53, the dichroic mirror 501, the scanning unit 63, and the objective lens 64, and finally enters the sample area to be welded. The camera-assisted function operates on the sample arm optical path module 44 by having the light returning from the sample to be welded pass sequentially through the objective lens 64, scanning unit 63, dichroic mirror 501, and dichroic mirror 53, finally being imaged onto the camera module 52. The calibration components include a calibration reflector 48 and an optical path refraction element 65. The dichroic mirror 501 is positioned at the beam-combining point of the OCT measurement optical path and the welding processing optical path, allowing the OCT detection light and welding light to share the scanning unit 63 and objective lens 64 for incident on the sample to be welded. The dichroic mirror 53 is positioned at the beam-combining or beam-splitting point of the welding processing optical path and the camera optical path, guiding the welding light into the welding processing optical path and directing the visible light, near-infrared light, or other auxiliary imaging light returning from the sample to be welded to the camera module 52.

[0077] The welding unit 61 is used to output welding light. The welding light collimator 62 is used to collimate the welding light output by the welding unit 61 into a welding beam suitable for subsequent scanning and focusing. The scanning unit 63 is used to control the incident position or scanning trajectory of the welding light and OCT detection light on the sample to be welded. The objective lens 64 is used to focus the welding light onto the welding area of ​​the sample to be welded, and to focus or collimate the OCT detection light onto the detection area of ​​the sample to be welded.

[0078] In OCT detection mode, scanning mirror 47 scans the sample, causing the OCT detection light to enter the OCT measurement optical path via dichroic mirror 501, and then be incident on the welding area of ​​the sample to be welded through scanning unit 63 and objective lens 64. The OCT detection light returning from the sample to be welded returns along the original path to interference module 42, and forms an interference signal with the reference arm light. After being acquired by acquisition module 3, the OCT measurement signal S1 is obtained. The OCT measurement signal S1 can be used to obtain parameters related to the surface height, keyhole depth, weld penetration, weld morphology, or welding process status of the sample to be welded.

[0079] In the calibration state, the scanning mirror 47 is deflected to the calibration angle, causing the OCT measurement light to deviate from the OCT detection light path and be incident on the optical path folding element 65. The optical path folding element 65 is used to change the propagation direction of the calibration light path, so that the calibration light is incident on the calibration reflector 48 along the folded calibration light path. The light returned from the calibration reflector 48 returns to the interference module 42 via the optical path folding element 65 and the scanning mirror 47, and forms a calibration interference signal with the reference arm light. After being acquired by the acquisition module 3, the calibration signal K1 is obtained.

[0080] Processing module 1 generates interpolation correction parameters based on calibration signal K1 and performs OCT interpolation correction on previously or subsequently acquired OCT measurement signals S1. The interpolation correction parameters may include one or more of the following: time-wavenumber mapping relationship, pixel-wavenumber mapping relationship, optical path delay correction parameters, or scanning nonlinearity correction parameters.

[0081] The optical path reversing element 65 can be a mirror, prism, right-angle prism, pyramidal prism, metal reflector, coated glass plate, or other optical element capable of changing the direction of beam propagation. By setting the optical path reversing element 65 in the calibration optical path, the spatial position of the calibration reflector 48 relative to the scanning mirror 47 can be changed, so that the calibration reflector 48 does not have to be arranged along the direct emission direction of the scanning mirror 47. As a result, the calibration optical path can be folded and arranged in the empty space inside the welding head, thereby reducing the overall volume and size of the welding head.

[0082] In laser welding OCT inspection systems, the welding head typically needs to be mounted on a robot end effector, motion platform, galvanometer welding head, or other industrial motion mechanism. If the welding head is too large or too heavy, it increases the motion load, reduces the equipment's dynamic response capability, and affects on-site installation and maintenance. This embodiment folds the calibration optical path using the optical path folding element 65, allowing the scanning mirror 47, calibration reflector 48, and calibration optical path to adopt a more compact spatial layout. This facilitates the creation of a small, lightweight, and easily integrated low-cost laser welding OCT inspection device.

[0083] In this embodiment, the optical path relationship between the scanning mirror 47, the calibration reflector 48, the zero optical path difference position of the OCT system, and the interface to be measured of the sample to be welded can be referred to in Embodiment 3 regarding... , and The description will not be repeated here.

[0084] This embodiment can be used to obtain parameters related to the surface height of the sample to be welded, keyhole depth, weld penetration, weld morphology, or welding process status during laser welding. It can also reduce the volume and weight of the welding OCT detection head by folding the calibration optical path.

Claims

1. A scanning multiplexed optical coherent measurement system, characterized in that, It includes a processing module, a control module, a data acquisition module, and an OCT optical path module; The OCT optical path module includes an OCT laser, an interference module, a polarization controller, a sample arm optical path module, and a photoelectric conversion module; The sample arm optical path module includes a scanning mirror and a calibration component; The calibration component includes a calibration reflector; The scanning mirror has a measurement state and a calibration state; Adjusting the polarization controller state can change the intensity of the OCT measurement signal S1 and the calibration signal K1; In the measurement state, the scanning mirror directs the OCT measurement light onto the sample to be measured, and the sample return light interferes with the reference arm light to obtain the OCT measurement signal S1; In the calibration state, the scanning mirror is deflected to the calibration angle, causing the OCT measurement light to deviate from the OCT measurement optical path and be incident on the calibration component. The light returned by the calibration component interferes with the reference arm light to obtain the calibration signal K1. The processing module generates interpolation correction parameters based on the calibration signal K1, and uses the interpolation correction parameters to interpolate and correct the OCT measurement signal S1. The measurement and calibration states share the same OCT laser, interference module, polarization controller, sample arm optical path module, photoelectric conversion module, acquisition module, and processing module.

2. The optical coherence measurement system for scanning multiplexing according to claim 1, characterized in that, The processing module is connected to the control module and the acquisition module respectively; the interference module is connected to the OCT laser, the polarization controller and the photoelectric conversion module respectively; the polarization controller is located between the interference module and the sample arm optical path module; the photoelectric conversion module is connected to the interference module and the acquisition module respectively; the sample arm optical path module is used to direct the OCT measurement light onto the sample to be tested and to receive the sample arm return light returned by the sample to be tested.

3. The optical coherence measurement system for scanning multiplexing according to claim 1, characterized in that, The control module is used to generate and / or receive timing control signals required for system operation according to the system control commands output by the processing module; the timing control signals include a first timing signal T1, a second timing signal T2, and a third timing signal T3; the first timing signal T1 is used to synchronize the working state of the OCT laser; the second timing signal T2 is used to control the sample arm optical path module to switch between measurement state and calibration state; the third timing signal T3 is used to trigger the acquisition module to acquire data.

4. The optical coherence measurement system for scanning multiplexing according to claim 1, characterized in that, The calibration component includes a calibration reflector, which includes one or more sub-reflector units; the calibration reflector is a mirror, a hollow mirror, a right-angle prism, a corner prism, a glass plate, a metal plate, or other devices and / or modules with beam reflection capabilities. When the calibration reflector includes multiple sub-reflection units, different sub-reflection units have different optical path differences with the scanning mirror to form multiple calibration signals K1 of different frequencies; The processing module stores pre-calibrated optical path difference values ​​corresponding to different sub-reflection units, and performs interpolation correction and depth correction on the OCT measurement signal S1 based on the pre-calibrated optical path difference values ​​and multiple calibration signals K1 of different frequencies.

5. The optical coherence measurement system for scanning multiplexing according to claim 1, characterized in that, The calibration component includes an optical path folding element and a calibration reflector. The optical path folding element is disposed between the scanning mirror and the calibration reflector. In the calibration state, the scanning mirror causes the OCT measurement light to deviate from the OCT measurement optical path and be incident on the optical path folding element. The optical path folding element changes the propagation direction of the calibration optical path, so that the calibration light is incident on the calibration reflector along the folded calibration optical path.

6. The optical coherence measurement system for scanning multiplexing according to claim 1, characterized in that, The optical path difference between the scanning mirror and the calibration reflector is: The optical path difference between the scanning mirror and the upper surface or interface of the sample to be tested is The optical path difference between the scanning mirror and the zero optical path difference position of the OCT system is ; The zero optical path difference position of the OCT system is located above the upper surface of the sample or the interface to be measured, and Less than 10% of the maximum imaging depth of the OCT system, and meets the following requirements: .

7. The optical coherence measurement system for scanning multiplexing according to claim 1, characterized in that, The optical path difference between the scanning mirror and the calibration reflector The optical path difference is less than the optical path difference between the scanning mirror and the zero optical path difference position of the OCT system. and satisfy as well as The calibration signal K1 generated by the calibration reflector and the OCT measurement signal S1 generated by the upper surface or interface of the sample under test are located on both sides of the zero optical path difference position of the OCT system.

8. The optical coherence measurement system for scan multiplexing according to any one of claims 1 to 7, characterized in that, The sample arm optical path module is an anterior segment OCT sample arm optical path module, including a collimator, a scanning mirror, a calibration component, a lens group one, a dichroic mirror one, and a camera module; the calibration component includes a calibration reflector; the collimator, scanning mirror, dichroic mirror one, and lens group one are sequentially connected in optical path, the camera module is connected to the dichroic mirror one in optical path, and the calibration reflector is connected to the scanning mirror in optical path; in the measurement state, the scanning mirror causes the OCT measurement light to be incident on the sample to be measured through the dichroic mirror one and the lens group one; in the calibration state, the scanning mirror causes the OCT measurement light to deviate from the OCT measurement optical path and be incident on the calibration reflector.

9. The optical coherence measurement system for scan multiplexing according to any one of claims 1 to 7, characterized in that, The sample arm optical path module is a posterior segment OCT sample arm optical path module, including a collimator, scanning mirror, calibration component, lens group one, lens group two, electric displacement device, dichroic mirror one, dichroic mirror two, camera module, lens group three, and fixation screen; the calibration component includes a calibration reflector; the collimator, scanning mirror, lens group one, dichroic mirror one, and lens group two are sequentially optically connected; the camera module is optically connected to dichroic mirror one; the fixation screen, lens group three, dichroic mirror two, dichroic mirror one, and lens group two are sequentially optically connected; the calibration reflector... The electric displacement device is mechanically connected to the lens group two and connected to the scanning mirror optical path. The lens group one and the lens group two form a 4F optical path, which is used to make the plane where the scanning mirror is located and the position of the pupil of the eye to be measured form a conjugate relationship. The electric displacement device is used to drive the lens group two to move along the optical axis, so that the OCT optical path and the fixation optical path can be focused at the same time. In the measurement state, the scanning mirror causes the OCT measurement light to be incident on the sample to be measured through the lens group one, the dichroic mirror one, and the lens group two. In the calibration state, the scanning mirror causes the OCT measurement light to deviate from the OCT measurement optical path and be incident on the calibration reflector.

10. The optical coherence measurement system for scan multiplexing according to any one of claims 1 to 7, characterized in that, The sample arm optical path module is a laser welding OCT sample arm optical path module, including a collimator, a zoom lens, a scanning lens, a calibration component, a dichroic mirror one, a dichroic mirror two, a welding unit, a welding light collimator, a scanning unit, and an objective lens; the calibration component includes a calibration reflector and an optical path refraction element; the collimator, zoom lens, scanning lens, dichroic mirror one, scanning unit, and objective lens are sequentially optically connected to form an OCT measurement optical path; the welding unit, welding light collimator, dichroic mirror two, dichroic mirror one, scanning unit, and objective lens are sequentially optically connected to form a welding optical path; the optical path refraction element is disposed between the scanning lens and the calibration reflector; in the calibration state, the scanning lens causes the OCT measurement light to deviate from the OCT measurement optical path and be incident on the optical path refraction element, and the optical path refraction element changes the propagation direction of the calibration light path, so that the calibration light is incident on the calibration reflector.

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