Laser illumination system and image acquisition system

Abstract

The invention provides a laser illumination system and an image acquisition system, and the system comprises a front-end integrated device which is used for converting emitted laser into collimated light; the dye box is arranged on one side of the front-end integration device, and the front-end integration device guides the collimated light to the dye box and excites dye fluorescence; the rear-end integration device is arranged on one side, far away from the front-end integration device, of the dye box, and the dye fluorescence is focused by the rear-end integration device, converted into collimated fluorescence and emitted into the surface of the to-be-detected object. The laser with high intensity and large energy is selected as a light source, the problem of low residual light intensity can be effectively solved, meanwhile, the laser excites dye molecules to generate fluorescence through the dye box, the phase of the laser is changed, coherence of the laser is eliminated, and therefore the purpose of eliminating laser spots is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of non-contact measurement, and in particular to a laser lighting system and an image acquisition system. Background Art

[0002] The hot end components of aircraft engines are in extreme environments of high temperature and high pressure for a long time. The detection of their working status / health status is of great significance for the safety and long-term service of the engine, especially the strain field detection problem of turbine rotor blades. At present, the object deformation measurement methods can be mainly divided into two categories: contact and non-contact (optical). Although contact measurement has high sensitivity, the measured data is very limited, and wiring is difficult. It has a large change to the structure of the engine and is easy to affect the aerodynamic performance of the blade. The non-contact measurement methods mainly include optical extensometer method, photogrammetry method, speckle interferometry method, projection grating method, optical flow method and digital image correlation (DIC) method. Among them, the DIC method has the advantages of simple optical path and low requirements for the measurement environment, and has irreplaceable advantages in the measurement of surface deformation of high-temperature objects.

[0003] The DIC method collects images (speckle fields) of the surface of the object before and after deformation, performs correlation processing, and solves the displacement of the speckle field to measure the deformation field of the object. Therefore, the clarity of the captured image determines the accuracy of the deformation measurement, and the choice of lighting method has also become a crucial factor. Compared with the light generated by spontaneous radiation of traditional lighting sources, laser is light generated by stimulated radiation, which has the advantages of good directionality, high brightness, high electro-optical conversion efficiency, and long life. It has natural advantages in special lighting scenes such as no ambient light and small spaces.

[0004] Laser has good monochromaticity and coherence. When a laser beam is irradiated on the surface of an object, the unevenness of the surface will cause the reflected light to have an optical path difference. They interfere with each other, some are constructive, and some are destructive, eventually forming irregularly distributed bright and dark spots, which are called laser coherent spots. Strain measurement based on the DIC method requires randomly spraying a series of black and white feature points (speckle) on the surface of the object as a mark for DIC measurement, which undoubtedly increases the roughness of the surface of the object to be measured. At this time, the uneven spot produced by laser illumination will affect the quality of the collected image, resulting in a decrease in the calculation accuracy of the subsequent strain field.

[0005] However, some existing methods for eliminating laser coherent light spots require complex optical path or structural design, integration, manufacturing, and corresponding calibration and verification, which greatly increases the complexity of the device and experimental process. Therefore, a simpler and more convenient solution is urgently needed for eliminating coherent light spots. Summary of the invention

[0006] In view of this, the embodiments of this specification provide a laser illumination system and an image acquisition system to meet the needs of narrow space illumination and DIC image acquisition.

[0007] The embodiments of this specification provide the following technical solutions: a laser illumination system, comprising: a front-end integrated device, used to convert the emitted laser into collimated light; a dye box, arranged on one side of the front-end integrated device, the front-end integrated device guides the collimated light to the dye box and excites the dye fluorescence; a back-end integrated device, arranged on the side of the dye box away from the front-end integrated device, the dye fluorescence is focused and converted into collimated fluorescence by the back-end integrated device, and then emitted into the surface of the object to be measured.

[0008] Furthermore, the front-end integrated device includes: a laser for generating laser light; an output optical fiber connected to the laser and used to output the laser light; and a collimating lens group arranged between the output optical fiber and the dye box, used to convert the laser light into collimated light and introduce it into the dye box.

[0009] Furthermore, the collimating lens group includes a plurality of lenses.

[0010] Furthermore, the back-end integrated device includes: a focusing lens group, which is arranged on the side of the dye box away from the front-end integrated device, and the focusing lens group is used to focus the divergent dye fluorescence; an inlet optical fiber and an optical fiber output beam expander, the inlet optical fiber is connected to the optical fiber output beam expander, and the inlet optical fiber is used to receive the focused dye fluorescence and transmit it to the optical fiber output beam expander for emission; a reflector, which is arranged downstream of the optical path of the optical fiber output beam expander, and the reflector is used to emit the collimated fluorescence emitted by the optical fiber output beam expander into the surface of the object to be measured.

[0011] Furthermore, the focusing lens group includes a plurality of lenses.

[0012] The present invention also provides an image acquisition system, comprising the above-mentioned laser illumination system.

[0013] Furthermore, the image acquisition system also includes: a probe system, a spectroscope, a first high-speed camera and a second high-speed camera. The probe system is used to collect image information of the surface of the object to be measured and form synthetic light to be emitted to the spectroscope. The spectroscope divides the synthetic light into a reflection spectrum and a transmission spectrum. The first high-speed camera is used to collect a first electrical signal formed by the reflection spectrum, and the second high-speed camera is used to collect a second electrical signal formed by the transmission spectrum.

[0014] Furthermore, the image acquisition system also includes: a first light splitting path and a first photodetector, the reflected spectrum enters the first photodetector through the first light splitting path to obtain a corresponding first electrical signal; a first receiving optical path, the first electrical signal enters the first high-speed camera through the first receiving optical path.

[0015] Furthermore, the image acquisition system also includes: a second light splitting path and a second photodetector, the transmission spectrum enters the second photodetector through the second light splitting path to obtain a corresponding second electrical signal; a second receiving optical path, the second electrical signal enters the second high-speed camera through the second receiving optical path.

[0016] Furthermore, there are at least two laser lighting systems.

[0017] Compared with the prior art, at least one of the above-mentioned technical solutions adopted in the embodiments of this specification can achieve at least the following beneficial effects: the present invention uses a high-intensity and high-energy laser as a light source to effectively solve the problem of low residual light intensity. At the same time, the laser passes through the dye box to excite the dye molecules to produce fluorescence, which changes the phase of the laser and eliminates the coherence of the laser, thereby achieving the purpose of eliminating the laser spot. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a schematic diagram of the structure of the laser lighting system of the present invention;

[0020] Figure 2 It is a structural schematic diagram of the image acquisition system of the present invention.

[0021] The reference numerals in the figure are: 1. laser; 2. optical fiber; 3. collimating lens group; 4. dye box; 5. focusing lens group; 6. optical fiber; 7. optical fiber output beam expansion; 8. reflector; 9. surface of the object to be measured; 14. spectroscope; 15. probe system; 101. first high-speed camera; 102. second high-speed camera; 111. first receiving light path; 112. second receiving light path; 121. first photodetector; 122. second photodetector; 131. first split light path; 132. second split light path. DETAILED DESCRIPTION

[0022] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0023] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0024] like Figure 1As shown, an embodiment of the present invention provides a laser illumination system, including a front-end integrated device, a dye box 4 and a back-end integrated device. The front-end integrated device is used to convert the emitted laser into collimated light; the dye box 4 is arranged at one side of the front-end integrated device, and the front-end integrated device guides the collimated light to the dye box 4 and excites the dye fluorescence; the back-end integrated device is arranged at a side of the dye box 4 away from the front-end integrated device, and the dye fluorescence is focused and converted into collimated fluorescence by the back-end integrated device, and then emitted into the surface 9 of the object to be measured.

[0025] The structural dimensions of the lighting device in a limited space are limited, and the lighting light needs to be introduced through optical fiber. The light intensity loss in the process is relatively large. It is difficult for a general LED light source to meet the lighting needs. The present invention uses a high-intensity, high-energy laser as a light source to effectively solve the problem of low residual light intensity. At the same time, the laser passes through the dye box 4 to excite the dye molecules to produce fluorescence, which changes the phase of the laser and eliminates the coherence of the laser, thereby achieving the purpose of eliminating the laser spot.

[0026] The front-end integrated device includes a laser 1, an output optical fiber 2, and a collimating lens group 3. The laser 1 is used to generate laser light; the output optical fiber 2 is connected to the laser 1 and is used to output the laser light; the collimating lens group 3 is arranged between the output optical fiber 2 and the dye box 4, and is used to convert the laser light into collimated light and introduce it into the dye box 4.

[0027] The laser 1 is connected to the front end of the output optical fiber 2 through an optical fiber connector, and the rear end of the output optical fiber 2 is connected to the collimating lens group 3 by bolts. The optical fiber connector has a threaded nut and a stainless steel ferrule for easy coupling and assembly. The dye box 4 is a rectangular transparent structure with slots at both ends for fixing the front-end integrated device and the back-end integrated device.

[0028] like Figure 1 As shown, the back-end integrated device includes a focusing lens group 5, an introduction optical fiber 6, an optical fiber output beam expander 7 and a reflector 8. The focusing lens group 5 is arranged on the side of the dye box 4 away from the front-end integrated device, and the focusing lens group 5 is used to focus the dye fluorescence; the introduction optical fiber 6 and the optical fiber output beam expander 7, the introduction optical fiber 6 is connected to the optical fiber output beam expander 7, and the introduction optical fiber 6 is used to receive the dye fluorescence and transmit it to the optical fiber output beam expander 7 for emission; the reflector 8 is arranged downstream of the optical path of the optical fiber output beam expander 7, and the reflector 8 is used to emit the collimated fluorescence emitted by the optical fiber output beam expander 7 into the surface 9 of the object to be measured.

[0029] The rear end of the dye box 4 is connected to the introduction optical fiber 6 by bolts, and the rear end of the introduction optical fiber 6 is coupled to the optical fiber output expansion beam 7 by bolts. The rear end of the optical fiber output expansion beam 7 is connected to a sleeve, and a reflector 8 is installed in the sleeve. The installation angle of the reflector 8 is adjusted according to the illumination area of ​​the object to be measured.

[0030] Preferably, the collimating lens group 3 and the focusing lens group 5 in the embodiment of the present invention both include multiple lenses.

[0031] The laser beam generated by the laser 1 passes through the optical fiber connector and the output optical fiber 2 through the collimating lens group 3 to convert the divergent laser into collimated light. The light beam after the collimating lens group 3 is introduced into the dye box 4, and the high energy of the laser is used to excite the dye molecules to produce random phase fluorescence, which changes the coherence of the original laser. A focusing lens group 5 is assembled at the other end of the dye box 4 to focus and export the dye fluorescence. The dye fluorescence passes through the focusing lens group 5, the input optical fiber 6, and the optical fiber output beam expander 7 to become collimated fluorescence emission, and is emitted into the surface 9 of the object to be measured by the reflector 8.

[0032] The following uses a three-dimensional DIC binocular measurement system as an example to illustrate the illumination system and the laser speckle removal device involved in the embodiments of the present application.

[0033] Specifically, digital image correlation (DIC) is a method for measuring deformation and strain of an object surface. This method tracks the deformation process of the speckle pattern on the surface of the object, calculates the grayscale value change of the speckle domain, and thus obtains the deformation and strain data of the surface of the object being measured. According to the different ways of obtaining the speckle image and the calculation results, digital image correlation is also divided into two-dimensional DIC and three-dimensional DIC. The basic principle of three-dimensional DIC is based on the principle of binocular stereo vision. Two cameras at a certain angle to each other are used to shoot the surface of the object being measured. First, the binocular stereo vision model is calibrated to obtain the internal and external parameters of the two cameras. Then, the three-dimensional DIC algorithm is used to obtain the parallax of the corresponding points in the left and right images. The three-dimensional morphology of the surface of the object being measured is reconstructed from the parallax data of each point and the calibration parameters.

[0034] like Figure 2 As shown, the present invention also provides an image acquisition system, including the above-mentioned laser illumination system.

[0035] The image acquisition system specifically includes: a probe system 15, a spectroscope 14, a first high-speed camera 101 and a second high-speed camera 102. The probe system 15 is used to collect image information of the surface 9 of the object to be measured (the surface of the engine blade) and form a synthetic light to be emitted to the spectroscope 14. The spectroscope 14 divides the synthetic light into a reflection spectrum and a transmission spectrum. The first high-speed camera 101 is used to collect a first electrical signal formed by the reflection spectrum, and the second high-speed camera 102 is used to collect a second electrical signal formed by the transmission spectrum.

[0036] The image acquisition system in the embodiment of the present invention is a binocular vision acquisition system, which is equipped with two high-speed cameras (101 and 102) for capturing images at two angles on the surface of the engine blade.

[0037] The image information of the engine blade surface is transmitted through the probe system 15 and the constructed optical path for spectral energy transmission. A beam splitter 14 (two-way beam splitter) is set in the constructed optical path structure. The beam splitter 14 uses the refractive index difference between lights of different wavelength bands to achieve the purpose of spectral separation. Therefore, a beam of synthetic light can be divided into a reflection spectrum and a transmission spectrum through the beam splitter 14.

[0038] Preferably, the image acquisition system further comprises:

[0039] The first light splitting path 131, the first photodetector 121 and the first receiving light path 111. The reflected spectrum enters the first photodetector 121 through the first light splitting path 131 to obtain a corresponding first electrical signal; the first electrical signal enters the first high-speed camera 101 through the first receiving light path 111 for signal processing and imaging.

[0040] The second light splitting path 132, the second photodetector 122 and the second receiving light path 112, the transmission spectrum enters the second photodetector 122 through the second light splitting path 132 to obtain a corresponding second electrical signal; the second electrical signal enters the second high-speed camera 102 through the second receiving light path 112 for signal processing and imaging.

[0041] Figure 2 The embodiment shown is a binocular vision acquisition system, which is suitable for the acquisition of blade surface deformation images with complex curved morphology. Accordingly, the binocular vision acquisition system needs to be equipped with two sets of laser lighting systems. Figure 2 For simplicity, only one of the light source systems is shown. The two laser illumination systems provide illumination lights of two different wavelengths, which are distinguished and collected through two different optical paths, which can effectively prevent mutual interference between the two high-speed cameras. Therefore, in the two laser illumination systems, different fluorescent dye reagents are used to excite dye fluorescence of different wavelengths to meet the matching and distinction between the subsequent cameras and the captured images.

[0042] The optional wavelengths for exciting fluorescence include ultraviolet excitation light (200-400nm), BP Fluor 350 can be used as the dye; blue excitation light (400-500nm), BP Fluor 430 can be used as the dye; green excitation light (500-570nm), rhodamine solution can be used as the dye; orange excitation light (590-620nm), MB 954 can be used as the dye; red excitation light (620-660nm), BP Fluor 633 can be used as the dye; near-infrared excitation light (660-700nm), BP Fluor 680 can be used as the dye. Technicians can select different fluorescent dye agents according to shooting requirements to obtain different illumination light band combinations, for example, BP Fluor 430 and rhodamine solution are selected as fluorescent dye agents for two light source systems to excite blue light and green light respectively. The above two beams of light illuminate the surface of the engine blade together, and the deformation information of the surface enters the optical path through the probe system and is separated into blue and green light at the spectroscope 14. The blue light enters the first high-speed camera 101 through the first spectroscope 131 and the first receiving optical path 111, and the green light passes through the spectroscope 14 and passes through the second spectroscope 132 and the second receiving optical path 112 to be captured by the second high-speed camera 102. The above two high-speed cameras only process the photoelectric signals of their respective bands. The two high-speed cameras are independent of each other and do not interfere with each other, thereby achieving the purpose of real-time synchronous acquisition of the binocular vision system.

[0043] The above is only a specific embodiment of the present invention, and cannot be used to limit the scope of the invention. Therefore, the replacement of equivalent components, or equivalent changes and modifications made according to the protection scope of the present invention, should still fall within the scope of this patent. In addition, the technical features of the present invention can be freely combined with each other, with each other, and with each other.

Claims

1. A laser lighting system, characterized in that: include: A front-end integrated device for converting the emitted laser light into collimated light; A dye box (4) is arranged on one side of the front-end integrated device, and the front-end integrated device guides collimated light to the dye box (4) and excites dye fluorescence; The back-end integrated device is arranged on a side of the dye box (4) away from the front-end integrated device. The dye fluorescence is focused and converted into collimated fluorescence by the back-end integrated device and then emitted to the surface (9) of the object to be tested.

2. The laser illumination system according to claim 1, characterized in that: The front-end integrated device comprises: A laser (1) for generating laser light; An output optical fiber (2), connected to the laser (1) and used to output the laser light; The collimating lens group (3) is arranged between the output optical fiber (2) and the dye box (4) and is used for converting the laser into collimated light and introducing the collimated light into the dye box (4).

3. The laser illumination system according to claim 2, characterized in that: The collimating lens group (3) comprises a plurality of lenses.

4. The laser illumination system according to claim 1, characterized in that: The back-end integration device comprises: A focusing lens group (5) is arranged on a side of the dye box (4) away from the front-end integrated device, and the focusing lens group (5) is used to focus the dye fluorescence; An inlet optical fiber (6) and an optical fiber output beam expander (7), wherein the inlet optical fiber (6) is connected to the optical fiber output beam expander (7), and the inlet optical fiber (6) is used to receive dye fluorescence and transmit it to the optical fiber output beam expander (7) for emission; The reflector (8) is arranged downstream of the optical path of the optical fiber output beam expander (7), and is used to direct the collimated fluorescence emitted by the optical fiber output beam expander (7) into the surface (9) of the object to be measured.

5. The laser illumination system according to claim 4, characterized in that: The focusing lens group (5) comprises a plurality of lenses.

6. An image acquisition system, comprising a laser illumination system, characterized in that: The laser illumination system is the laser illumination system according to any one of claims 1 to 5.

7. The image acquisition system according to claim 6, characterized in that: include: A probe system (15), a spectroscope (14), a first high-speed camera (101) and a second high-speed camera (102), wherein the probe system (15) is used to collect image information of the surface (9) of the object to be measured and form synthetic light to be emitted to the spectroscope (14), the spectroscope (14) separates the synthetic light into a reflection spectrum and a transmission spectrum, the first high-speed camera (101) is used to collect a first electrical signal formed by the reflection spectrum, and the second high-speed camera (102) is used to collect a second electrical signal formed by the transmission spectrum.

8. The image acquisition system according to claim 7, characterized in that: The image acquisition system also includes: A first light splitting path (131) and a first photodetector (121), wherein the reflected spectrum enters the first photodetector (121) through the first light splitting path (131) to obtain a corresponding first electrical signal; A first receiving optical path (111), through which the first electrical signal enters the first high-speed camera (101).

9. The image acquisition system according to claim 7, characterized in that: The image acquisition system also includes: A second light splitting path (132) and a second photodetector (122), wherein the transmission spectrum enters the second photodetector (122) through the second light splitting path (132) to obtain a corresponding second electrical signal; A second receiving optical path (112), through which the second electrical signal enters the second high-speed camera (102).

10. The image acquisition system according to any one of claims 6 to 9, characterized in that: The laser lighting system comprises at least two sets.

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