Optical fiber bundle-based light source and monochromator coupling method and system

Abstract

The invention discloses a light source and monochromator coupling method and system based on an optical fiber bundle. According to the system, extremely strong light energy is required to be input into the monochromator to overcome monochromatic light intensity attenuation caused by expansion of the light energy in a frequency domain, so that high-intensity spectrum-adjustable monochromatic light meeting the test requirement is obtained. According to the invention, the plasticity of the end face of the optical fiber bundle is utilized to construct a circular-rectangular light spot shape conversion bridge. The input end of the optical fiber bundle is shaped into a circle so as to efficiently receive and gather circular light spots from a high-power xenon lamp light source; and the output end is shaped into a rectangle matched with the entrance slit of the monochromator, so that output light spots are perfectly matched with the monochromator in spatial distribution. According to the method, the coupling efficiency bottleneck between a traditional circular light spot light source and a monochromator slit input mode is solved, and compared with a tunable laser scheme, the cost is remarkably reduced; the device has the outstanding advantages of simpler structure, more compact space, more convenient integration and extremely high light energy utilization rate.

Description

Technical Field

[0001] This invention relates to a method and system for achieving efficient coupling between a light source and a monochromator using an optical fiber bundle, belonging to the field of optical testing and optical detection technology. Background Technology

[0002] In the optical performance testing of aerospace-grade image sensors with resolutions exceeding 100 megapixels, international standards (such as EMVA 1288) require the provision of monochromatic light with tunable wavelength and sufficient intensity. A common approach is to use a high-power xenon lamp as the light source, coupled with a monochromator, to generate this type of light. However, this approach faces two core challenges: 1. Light energy attenuation of the monochromator itself: Light energy undergoes dispersion and sifting within the monochromator, causing its output light intensity to drop sharply relative to the input. In order to provide sufficiently intense monochromatic light to the super-megapixel sensor under test, an extremely high initial light energy must be input into the monochromator.

[0003] 2. Coupling efficiency bottleneck caused by light spot shape mismatch: The entrance of the monochromator is a slit structure (usually rectangular), while the conventional xenon lamp light source forms a circular light spot after focusing. This severe geometric mismatch means that most of the light energy cannot enter the monochromator, resulting in extremely low efficiency of traditional coupling methods, which becomes a bottleneck restricting the performance of the entire testing system.

[0004] Currently, the alternative solution to meet the demand for high-intensity monochromatic light is to use wavelength-tunable lasers, but their cost is extremely high, making widespread adoption difficult. While using complex lens groups for spot shaping can partially solve the shape problem, it suffers from issues such as complex system structure, long optical paths, large space occupation, difficult assembly and adjustment, and the introduction of additional aberrations. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: the purpose of the present invention is to provide a method and system for coupling a light source and a monochromator based on an optical fiber bundle, to solve the problem of light spot shape conversion, and to optimize the simplicity and stability of the optical path at the system level.

[0006] The technical solution adopted in this invention is: a method for coupling a light source and a monochromator based on an optical fiber bundle, comprising: The output end of the fiber bundle is molded into the shape of the monochromator input port; Adjust the light from the light source so that it converges onto the input end face of the fiber optic bundle, forming the first input light spot; After the first light spot is transmitted through the fiber bundle, the second light spot is output at the output end face of the fiber bundle. After passing through the second converging optical path, the second light spot forms a third light spot that is compatible with the monochromator inlet, and the third light spot is input into the monochromator.

[0007] Furthermore, the output port shape of the optical fiber bundle can be arbitrarily molded according to the needs of the monochromator adapter interface, and the input end face and output end face of the optical fiber bundle have the same area.

[0008] Furthermore, the fiber optic bundle inlet end is inserted into the center hole of the aluminum alloy flange, and the fiber optic bundle is protected by an external metal flexible hose.

[0009] Furthermore, the fiber optic bundle outlet is inserted into an aluminum alloy port, the central hole of which is shaped like the monochromator input port, and the aluminum alloy port is cylindrical in shape.

[0010] Furthermore, the optical fibers within the optical fiber bundle are glass optical fibers, quartz optical fibers, or plastic optical fibers.

[0011] Furthermore, the fiber bundle can also be liquid fiber or a light guide tube.

[0012] A light source and monochromator coupling system based on an optical fiber bundle includes: a light source, a first converging optical path, an optical fiber bundle, and a second converging optical path; The light from the light source is converged to the input end face of the fiber bundle through the first converging optical path, forming the first input light spot; the output end of the fiber bundle is molded into the shape of the monochromator input port; After the first light spot is transmitted through the fiber bundle, the second light spot is output at the output end face of the fiber bundle. After the second light spot passes through the converging optical path, it forms a third light spot that is compatible with the monochromator inlet. The third light spot is then input into the monochromator.

[0013] The advantages of this invention compared to the prior art are: This invention significantly improves optical energy coupling efficiency through beam coupling, enabling the monochromator to output monochromatic light with tunable spectrum and high intensity. Compared to wavelength-tunable lasers, the cost is greatly reduced; compared to traditional lens coupling schemes, this invention has a simpler structure, occupies less space, and is more easily integrated and portable. Attached Figure Description

[0014] Figure 1 This is a cross-sectional view of the fiber bundle end face (the shaded area represents the fiber in the fiber bundle, and the areas at both ends are equal); Figure 2 Schematic diagram of fiber bundle coupled light source and monochromator; Figure 3 Perspective view of the fiber optic bundle side flange adapter interface; Figure 4 This is a schematic diagram of the aluminum alloy roll-molded structure at the fiber optic bundle outlet. Detailed Implementation

[0015] The present invention will be described in conjunction with the accompanying drawings.

[0016] The present invention aims to provide a low-cost, high-efficiency, and compact light source-monochromator coupling method to solve the above-mentioned bottlenecks and provide reliable optical input guarantee for the aerospace-grade image sensor testing system with over 100 million images.

[0017] A method for coupling a light source and a monochromator based on an optical fiber bundle is provided. The coupling optical fiber bundle used to connect the light source and the monochromator has two end faces with different shapes. The end of the optical fiber bundle coupled to the light source is the light input end, and its end face is circular, which is suitable for coupling with most light sources. The end of the optical fiber bundle coupled to the monochromator is the light output end, and its end face is rectangular, which is suitable for further coupling of the output light of the optical fiber bundle to the monochromator. The light output from the fiber bundle can be conditioned by a collimating lens and a converging lens or by other converging optical paths to form a rectangular light spot similar in shape to the output end face of the fiber bundle, which is adapted to the efficient coupling of the output light with the monochromator. The output optical end face of the fiber bundle can be of other different shapes in order to couple with the compatible equipment; The fiber bundle can contain glass fiber, quartz fiber, or plastic fiber. The fiber bundle can also be liquid fiber or other light guiding channels.

[0018] A light source-monochromator coupling method for a test system of an ultra-high-resolution image sensor for aerospace applications is disclosed. The system comprises, in sequence, a high-power xenon lamp light source 1, a coupling device, a monochromator, a shutter aperture assembly, an integrating sphere, and a two-dimensional electrically driven displacement stage. The coupling method employs a specially designed fiber optic bundle, which serves as the core component for optical path transmission and shape conversion. Its specific details are as follows: Figure 2 As shown, the light from light source 1 is adjusted by optical path 2, which includes reflection and focusing, so that most of the light can be focused onto the input end face of fiber bundle 3 to form input light spot 4. After being conducted by fiber bundle, the light is output from its output end face. Since the output end of fiber bundle has been molded into a rectangle similar to the input port of monochromator, fiber bundle converts circular or other shaped light sources into rectangular light spot 5. After passing through focusing optical path 6, this rectangular light source forms light spot 7 that is very well matched to the entrance of monochromator 8, thereby greatly improving the optical coupling efficiency and making the light source input to monochromator a wavelength-tunable, high-power monochromatic light source.

[0019] The choice of fiber bundle type depends on the required spectral range of the monochromatic light source; different types of fiber bundles will have different passbands. Meanwhile, the fiber bundle outlet shape can be shaped into any form according to the needs of the adapter interface, but its cross-sectional area is basically equal to the cross-sectional area of ​​the fiber bundle inlet channel. For example, the areas of spot 4 and spot 5 are equal. Figure 1 .

[0020] The monochromator 8, coupled by the method of this invention, achieves an order-of-magnitude increase in output light energy. This high-intensity monochromatic light is then precisely controlled by a shutter aperture, ultimately forming a uniform and stable flat-field light within the integrating sphere. This light is used to illuminate a gigapixel image sensor placed on a two-dimensional electrically driven displacement slide, enabling a series of precise performance parameter tests.

[0021] Based on the numerical aperture of the optical fiber, a converging optical path composed of lenses is used to focus the light source and form a light spot. During this process, to control the luminous flux of each fiber from being overloaded, the converging optical path can be appropriately adjusted to make the light spot area sufficiently large, thereby relatively reducing the luminous load on a single fiber. When the illuminance of the light source is high, increasing the light spot area can also reduce the temperature of the light-receiving end face of the fiber bundle. The light source and converging optical path are optically sealed, with a light spot exit port provided for mating with the fiber bundle. The structure of the adapter interface and the fiber bundle input end is designed to ensure that the fiber bundle end face is precisely on the light spot and to isolate external ambient light from entering the light source package. The fiber bundle input end can be an aluminum alloy flange structure, such as... Figure 3 The flange through hole is the same size as the light spot, and the fiber bundle is protected by an external metal flexible hose.

[0022] According to the invention principle, the light spot 5 formed at the other end of the optical fiber bundle is rectangular, and therefore a specially designed shape is as follows: Figure 4 The aluminum alloy port is used to bundle the optical fiber into a rectangle; this port is a hollow cylinder within a cuboid. The cylinder is connected to a sleeve with a built-in converging lens at the front end. By appropriately selecting the lens focal length and diameter, and the sleeve insertion depth, a rectangular light spot suitable for coupling with the monochromator can be obtained. The sleeve is fixed using set screws, and further, a flange structure can be used to securely connect the sleeve to the monochromator. The light source is efficiently guided to the monochromator 8 using the above method. The monochromatic light output after dispersion by the monochromator 8, along with the auxiliary LED light source, enters the shutter-aperture assembly for intensity adjustment, and finally incident on the integrating sphere to form a uniformly illuminated light field.

[0023] Therefore, the coupling efficiency provided by this method directly determines the maximum available light intensity reaching the image sensor under test, which in turn affects the upper limit of the measurement of key indicators such as signal-to-noise ratio and dynamic range of the system test.

[0024] The parts of this invention not described in detail are well-known to those skilled in the art.

Claims

1. A method for coupling a light source and a monochromator based on an optical fiber bundle, characterized in that, include: The output end of the fiber bundle (3) is molded into the shape of the input port of the monochromator (8); Adjust the light from the light source (1) so that the light from the light source (1) is focused onto the input end face of the fiber bundle (3) to form the first input light spot (4). After the first light spot (4) is transmitted through the fiber bundle (3), the second light spot (5) is output at the output end face of the fiber bundle (3); After the second light spot (5) passes through the second converging optical path (6), it forms a third light spot (7) that is compatible with the entrance of the monochromator (8), and the third light spot (7) is input into the monochromator (8).

2. The method for coupling a light source and a monochromator based on an optical fiber bundle according to claim 1, characterized in that, The output port shape of the optical fiber bundle (3) can be arbitrarily shaped according to the needs of the monochromator adapter interface, and the input end face and output end face of the optical fiber bundle (3) have the same area.

3. The method for coupling a light source and a monochromator based on an optical fiber bundle according to claim 2, characterized in that, The fiber bundle (3) is inserted into the center hole of the aluminum alloy flange at its inlet end, and the fiber bundle (3) is protected by a metal flexible hose.

4. The method for coupling a light source and a monochromator based on an optical fiber bundle according to claim 3, characterized in that, The fiber bundle (3) is inserted into the aluminum alloy port at its outlet. The central hole of the aluminum alloy port is shaped like the input port of the monochromator (8), and the aluminum alloy port is cylindrical in shape.

5. The method for coupling a light source and a monochromator based on an optical fiber bundle according to claim 1, characterized in that, The optical fibers in the optical fiber bundle (3) are glass optical fibers, quartz optical fibers or plastic optical fibers.

6. The method for coupling a light source and a monochromator based on an optical fiber bundle according to claim 1, characterized in that, The fiber bundle (3) is a liquid optical fiber or a light guide tube.

7. A coupling system between a light source and a monochromator based on an optical fiber bundle, characterized in that, include: Light source (1), first converging optical path (2), fiber bundle (3), and second converging optical path (6); The light from the light source (1) is converged to the input end face of the fiber bundle (3) through the first converging optical path (2) to form the first input light spot (4); the output end of the fiber bundle (3) is molded into the shape of the input port of the monochromator (8); After the first light spot (4) is transmitted through the fiber bundle (3), the second light spot (5) is output at the output end face of the fiber bundle (3); After the second spot (5) passes through the converging optical path (6), it forms a third spot (7) that is compatible with the entrance of the monochromator (8), and the third spot (7) is input into the monochromator (8).

8. The optical fiber bundle-based light source and monochromator coupling system according to claim 7, characterized in that, The output port shape of the optical fiber bundle (3) can be arbitrarily shaped according to the needs of the monochromator adapter interface, and the input end face and output end face of the optical fiber bundle (3) have the same area.

9. A coupling system for a light source and a monochromator based on an optical fiber bundle according to claim 8, characterized in that, The fiber bundle (3) is inserted into the center hole of the aluminum alloy flange at its inlet end, and the fiber bundle (3) is protected by a metal flexible hose. The fiber bundle (3) is inserted into the aluminum alloy port at its outlet end. The center hole of the aluminum alloy port is shaped like the input port of the monochromator (8), and the aluminum alloy port is cylindrical in shape.

10. The optical fiber bundle-based light source and monochromator coupling system according to claim 1, characterized in that, The optical fibers in the optical fiber bundle (3) are glass optical fibers, quartz optical fibers or plastic optical fibers; the optical fiber bundle (3) can also be liquid optical fibers or light guides.

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