Miniature spectrometer with low temperature drift and high stability

Abstract

The low-temperature-drift high-stability micro spectrometer comprises a metal shell and an optical substrate, and the metal shell is provided with an inner cavity and a detected light beam inlet; the optical substrate is arranged in an inner cavity of the metal shell, a gap is formed between the peripheral surface of the optical substrate and the inner wall of the inner cavity, the optical substrate is provided with a slit, a photoelectric detector and a plurality of optical lenses, the slit is connected with a detected light beam inlet through a flexible optical waveguide, and a light beam incident from the slit generates a corresponding spectrum through the optical lenses; the photoelectric detector is used for detecting the spectrum; a flexible fixing piece is arranged on the peripheral surface of the optical substrate and is connected with the inner wall of the inner cavity; the optical substrate is made of a substrate material with a low expansion coefficient. With the adoption of the arrangement, the problem of size change of a photoelectric system material under external force compression and large-range temperature change can be better solved, and the conditions of intensity fluctuation and wavelength axis fluctuation of detected spectral data are reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of photoelectric testing equipment, and in particular relates to a low-temperature drift and high-stability miniature spectrometer. Background Art

[0002] The miniature grating spectrometer is a widely used spectral detection device that can be used for spectral detection in the ultraviolet, visible and near-infrared bands. It plays an important role in industry, environment, analysis and testing, aerospace and other fields, especially in the field of high-resolution spectral detection in a small volume. It is highly irreplaceable.

[0003] This type of spectrometer is usually implemented with an m-type or cross-type CT optical path. The main optical components in the system include slits, collimators, gratings, focusing lenses and photodetectors. Photodetectors usually use linear or planar array CCD or CMOS sensors. Currently, spectrometer products on the market are mainly implemented in the form of an aluminum alloy optical box + cover, which can take into account the strength, weight and manufacturing cost of the optical and mechanical structure.

[0004] However, the physical properties of the materials used in the above spectrometer solutions usually have the following two stability issues:

[0005] 1. When the optical machine housing is subjected to strong external pressure, the optical path is easily deformed, resulting in intensity fluctuations and wavelength axis fluctuations in the detected spectral data.

[0006] 2. When the spectroscopic instrument is in an environment with a large range of temperature changes, the temperature change properties of the material size of the optomechanical system will cause the wavelength axis to fluctuate, affecting the accuracy of the spectral data. In application scenarios such as online monitoring in the field and aerospace exploration, which are accompanied by vibrations, large changes in ambient temperature, and inability to implement high-frequency calibration, it is usually necessary to implement temperature control of the optomechanical system, which increases the system's power consumption, size, weight and complexity. Summary of the invention

[0007] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a low-temperature drift and high-stability miniature spectrometer, which can better overcome the problems of dimensional changes of optoelectronic system materials caused by external force pressure and large-range temperature changes, and reduce the intensity fluctuations and wavelength axis fluctuations of the detected spectral data.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] A low-temperature drift and high-stability micro-spectrometer comprises a metal shell and an optical substrate, wherein the metal shell has an inner cavity and a detected light beam entrance;

[0010] The optical substrate is arranged in the inner cavity of the metal shell, and there is a gap between the outer peripheral surface of the optical substrate and the inner wall of the inner cavity. A slit, a photoelectric detector and a plurality of optical lenses are arranged on the optical substrate. The slit is connected to the entrance of the detected light beam through a flexible optical waveguide. The light beam injected from the slit generates a corresponding spectrum through the optical lens, and the photoelectric detector is used to detect the spectrum.

[0011] A flexible fixing piece is arranged on the outer peripheral surface of the optical substrate, and the flexible fixing piece is connected to the inner wall of the inner cavity; the optical substrate is made of a substrate material with a low expansion coefficient.

[0012] Furthermore, the flexible fixing member is a rubber pad, and the number of the rubber pads is multiple, and the multiple rubber pads are evenly spaced along the annular direction around the outer periphery of the optical substrate.

[0013] Furthermore, a gap between the optical substrate and the inner wall of the inner cavity is sealed with flexible glue, and the sealed and cured flexible glue forms the flexible fixing member.

[0014] Furthermore, the flexible fixing member adopts a spring pad, and the number of the spring pads is multiple, and the multiple spring pads are distributed at intervals along a circular direction on the periphery of the optical substrate.

[0015] Furthermore, the flexible fixing frame adopts an airbag, the airbag is in a ring shape, and the airbag is arranged on the outer peripheral surface of the optical substrate.

[0016] Furthermore, the substrate material is quartz, glass-ceramics, alumina ceramics, silicon carbide or silicon nitride.

[0017] Furthermore, the optical lens includes one or more collimating lenses, beam splitting gratings or focusing lenses.

[0018] The present invention has the following beneficial effects:

[0019] 1. Use high-strength and low-temperature deformation coefficient materials (i.e., substrate materials with low expansion coefficients) to manufacture optical substrates to avoid temperature changes causing changes in the relative positions of components in the optical system, thereby achieving no significant spectral wavelength fluctuations within a large temperature change range.

[0020] 2. Use flexible fixings between the optical system and the instrument housing to avoid deformation of the metal housing caused by force, which may cause changes in the relative position of optical elements (i.e., optical lenses and related devices), thereby making the spectral detection results insensitive to external forces on the instrument and obtaining extremely stable spectral detection results; at the same time, avoid the common defects of low temperature deformation coefficient materials, such as high brittleness, low impact resistance, and poor machinability, without affecting the normal use and installation of the spectrometer.

[0021] 3. Compared with the prior art method of directly manufacturing the spectrometer structure using Invar alloy, although it can reduce the influence of external forces, it will bring about a significant increase in weight. The present invention uses a flexible fixing part to maintain the volume and weight of the spectrometer without significant changes, thus meeting the needs of existing application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0023] Figure 2 The graphs are mercury lamp spectra of the micro-spectrometer of the present invention at different temperatures.

[0024] Figure 3 The mercury lamp spectra of the traditional micro-spectrometer at different temperatures.

[0025] Figure 4 It is a simulation schematic diagram of the external force on the spectrometer of the present invention and the traditional spectrometer.

[0026] Figure 5 This is a mercury lamp spectrum diagram of the micro-spectrometer of the present invention under the force application range.

[0027] Figure 6 This is the mercury lamp spectrum of the traditional micro-spectrometer under the applied force range.

[0028] In the figure: 1. Metal casing; 11. Entrance of the detected light beam; 12. Flexible optical waveguide; 2. Optical substrate; 3. Slit; 4. Photodetector; 5. Flexible fixing part; 6. Collimating mirror; 7. Spectral grating; 8. Focusing mirror. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The terms such as "upper", "inner", "middle", "left", "right" and "one" cited in this specification are only for the convenience of description, and are not used to limit the scope of the present invention. The change or adjustment of their relative relationship shall also be regarded as the scope of the present invention without substantially changing the technical content.

[0030] Example 1

[0031] The spectrometer of the present invention is based on the problem in the prior art that the housing of the spectrometer is subjected to external force or the optical-mechanical system materials undergo dimensional deformation under a large range of temperature changes, which affects the accuracy of the detected spectral data. The structure of the spectrometer of the present invention is improved and designed to overcome the corresponding problem. The structure of the spectrometer of the present invention is further introduced below.

[0032] A low temperature drift and high stability micro spectrometer, such as Figure 1As shown, it includes a metal shell 1 and an optical substrate 2. The metal shell 1 has an inner cavity and a detected light beam entrance 11; the optical substrate 2 is arranged in the middle of the inner cavity of the metal shell 1, and there is a gap between the outer peripheral surface of the optical substrate 2 and the inner wall of the inner cavity. The optical substrate 2 is provided with a slit 3 mounting seat, a photodetector 4 and a plurality of optical lenses. The slit 3 mounting seat is provided with a slit 3, and the slit 3 is connected to the detected light beam entrance 11 through a flexible optical waveguide 12. The photodetector 4 and the optical lenses can be arranged at corresponding positions as needed. The detected light beam entrance 11 transmits the light beam to the slit 3 through the flexible optical waveguide 12, and the light beam emitted from the slit 3 generates a corresponding spectrum through the optical lens. The photodetector 4 is used to detect the spectrum in the inner cavity and generate corresponding detection data.

[0033] Among them, a flexible fixing part 5 is provided on the outer peripheral surface of the optical substrate 2, and the flexible fixing part 5 is connected to the inner wall of the inner cavity; therefore, when the surface of the metal shell receives external force, the impact force generated inward by the metal shell can be buffered by the flexible fixing part 5, thereby reducing the displacement or vibration of the optical substrate 2 when it is subjected to external force; at the same time, the optical substrate 2 is made of a substrate material with a low expansion coefficient, so when a spectrometer is used for photoelectric testing under a wide range of temperature changes, the optical substrate 2 can reduce the overall expansion or contraction of the optical substrate 2 due to the characteristics of its own material with a low expansion coefficient.

[0034] Therefore, by setting the flexible fixing part 5, the relative positions of the slit 3, the optical lens and the photodetector 4 on the optical substrate 2 can be prevented from changing when the metal housing 1 is subjected to external force, so that the spectral detection result is less susceptible to interference from the external force on the instrument, which is beneficial to improving the stability of the spectral detection result; at the same time, the flexible fixing part 5 can reduce the damage of the substrate material with a low expansion coefficient due to its high physical brittleness when it is impacted by external force, thereby improving the stability of the overall structure.

[0035] In this embodiment, the substrate material used for the optical substrate 2 can be quartz, microcrystalline glass, alumina ceramics, silicon carbide or silicon nitride. Therefore, under a wide range of temperature changes, the deformation of the optical substrate 2 itself is relatively weak, so it is not easy to change the relative positions of the slit 3, optical lens and photodetector 4 on the optical substrate 2, so as to achieve a situation where the spectrometer has no significant spectral wavelength fluctuation within a large temperature change range, so as to accurately measure the spectrum under a wide range of temperature changes.

[0036] In this embodiment, the optical lens includes one or more of a collimating lens 6, a spectroscopic grating 7 and a focusing lens 8. The selection of the optical lens is determined according to the actual needs of spectral detection, and the optical lens can be installed on the optical substrate 2 by screwing, or fixed to the optical substrate 2 by magnetic attraction, so it has the function of convenient installation.

[0037] The flexible fixing member 5 of the present invention adopts a variety of installation methods. The following is an introduction to the various installation structures of the flexible fixing member 5:

[0038] 1) The flexible fixing member 5 is a rubber pad, and there are multiple rubber pads. The multiple rubber pads are evenly distributed along the annular direction on the outer periphery of the optical substrate 2, so that the force distribution between the optical substrate 2 and the metal housing 1 can be uniform.

[0039] 2) The gap between the optical substrate 2 and the inner wall of the inner cavity is sealed with flexible glue, and the sealed and cured flexible glue forms a flexible fixing part 5 (also called a flexible rubber strip), thereby improving the buffering force between the optical substrate 2 and the inner wall of the inner cavity, thereby alleviating the impact of the metal shell 1 on the optical substrate 2 after being hit by external force, and then reducing the relative position changes of the slit 3, optical lens and photodetector 4 on the optical substrate 2, thereby improving the detection accuracy of the spectrometer.

[0040] 3) The flexible fixing part 5 adopts a spring pad, and there are multiple spring pads. The multiple spring pads are distributed at intervals along the annular direction on the outer periphery of the optical substrate 2, so that the force between the optical substrate 2 and the inner wall of the metal shell 1 is evenly distributed. When the metal shell 1 is hit, it can effectively buffer the impact force caused by the collision, thereby reducing the relative position changes of the slit 3, optical lens and photodetector 4 on the optical substrate 2, thereby improving the detection accuracy of the spectrometer.

[0041] 4) The flexible fixing member 5 is an airbag in a ring shape, and the airbag is arranged on the outer peripheral surface of the optical substrate 2. Therefore, when the metal housing 1 is hit, the airbag can effectively buffer the impact force generated to reduce the relative position change of the slit 3, the optical lens and the photodetector 4 on the optical substrate 2, thereby improving the detection accuracy of the spectrometer.

[0042] Experimental Example 1

[0043] Based on the above introduction to the low-temperature drift and high-stability micro-spectrometer of the present invention, in order to further verify that the improved micro-spectrometer of the present invention has significant beneficial effects compared with the conventional spectrometer in the prior art, the temperature drift performance of the low-temperature drift and high-stability micro-spectrometer is tested experimentally.

[0044] 1. Experimental preparation:

[0045] ① Regarding the low temperature drift and high stability micro-spectrometer of the present invention, the selection of key components is as follows:

[0046] The shell material of the metal shell 1 is 7 series aluminum alloy, which has the advantages of low cost, strong machinability, and good mechanical strength. The optical substrate 2 is made of quartz material, and the temperature deformation coefficient is about 2-5% of the aluminum alloy.

[0047] The flexible optical waveguide 12 is made of UV-resistant quartz optical fiber with a cladding, and its core diameter is 200 um.

[0048] The flexible fixing member 5 is potted in the gap between the metal housing 1 and the optical substrate 2 by using flexible glue.

[0049] The substrate material used for the optical substrate 2 is quartz, and any material whose temperature deformation coefficient is smaller than that of Invar alloy can be listed.

[0050] Spectrometer technical parameters: analysis range 470-810nm, focal length 75mm, M-type CT optical path, 3648 pixel linear array CCD detector.

[0051] ② Regarding the traditional micro-spectrometer, the selection of key components is as follows:

[0052] The shell material of the metal shell 1 is 7 series aluminum alloy, which has the advantages of low cost, high machinability, and good mechanical strength.

[0053] Spectrometer technical parameters: analysis range 470-810nm, focal length 75mm, M-type CT optical path, 3648 pixel linear array CCD detector.

[0054] 2. Temperature drift test method and results:

[0055] The micro-spectrometer of the present invention and the traditional micro-spectrometer are placed in a high and low temperature test box, and then a mercury lamp is used as a standard light source. The light source and the computer are set outside the test box to ensure normal operation. The test temperatures of the high and low temperature test box are selected as 20°C, 30°C, 40°C, 60°C, and 70°C, respectively. The equilibrium time (also called preheating time) of each temperature point before the test is not less than 30 minutes. During the test, the standard light source spectrum is collected three times, and the average value is obtained as the spectrum data of the current temperature point. After all temperature points are tested, a mercury element emission line is selected in each of the front, middle, and rear parts of the spectrum range to evaluate the lateral (pixel point position) drift distance of the spectrum peak.

[0056] Among them, in the low temperature drift high stability micro spectrometer of the present invention, the mercury lamp spectrum at different temperatures is as follows Figure 2 As shown; In the traditional micro-spectrometer, the spectrum of mercury lamp at different temperatures is as follows Figure 3 shown.

[0057] pass Figure 2 and Figure 3The temperature drift test results of this experiment can be obtained: the average spectral peak drift of the conventional spectrometer in the range of 20°C to 70°C is 5 pixels, while the average spectral peak drift of the spectrometer of the present invention is only 1 pixel in the same temperature range, which reflects excellent temperature-wavelength stability. At the same time, it can be seen that the optical substrate 2 of the present invention is made of a substrate material with a low expansion coefficient, and a flexible fixing part 5 is provided between the metal shell 1 and the optical substrate 2. In actual spectral testing, when the test environment temperature varies in a large range, compared with the conventional spectrometer, the overall expansion or contraction of the optical substrate 2 can be reduced, and the relative positions of the slit 3, optical lens and photodetector 4 on the optical substrate 2 can be prevented from changing, so it is beneficial to improve the stability of the spectral detection results, and at the same time, it is beneficial to improve the test accuracy of the spectrometer.

[0058] Experimental Example 2

[0059] Based on the experimental preparation in point 1 of the above experimental example 1, this experimental example is carried out. This experiment mainly applies force on the metal shell of the spectrometer to perform a spectrum peak drift test. The experimental method is as follows:

[0060] The micro-spectrometer of the present invention and the conventional micro-spectrometer are both placed on the ground and relatively fixed to the ground. The relative fixing methods of the two are consistent, and can be fixed through the mounting holes of the spectrometer itself or other unified fixing methods. Then, a mercury lamp is used as a standard light source. Under the premise of ensuring the normal operation of the light source and the computer, a force applying device (which can be a pendulum structure, an oblique slide and slider structure, a power trolley, etc.) is used to apply force (such as Figure 4 As shown), the applied force forms a torsional force. The same spectrometer is subjected to 5 forces, 10N, 20N, 30N, 40N, and 50N respectively. The micro-spectrometer of the present invention and the traditional micro-spectrometer both collect the standard light source spectrum three times during the test, and the average value is taken as the spectrum data of the current force application point. After all the force size tests are completed, a mercury element emission line is selected in each of the front, middle, and rear parts of the spectral range to evaluate the lateral (pixel point position) drift distance of the spectral peak.

[0061] Among them, in the low temperature drift high stability micro spectrometer of the present invention, the mercury lamp spectrum under different force magnitudes is as follows: Figure 5 As shown; In the traditional micro-spectrometer, the spectrum of the mercury lamp under different force magnitudes is shown as Figure 6 shown.

[0062] pass Figure 5 and Figure 6The force test results of this experiment can be obtained: the average spectral peak drift of the traditional spectrometer has a significant shift in the force range of 10N to 50N, while the average spectral peak drift of the spectrometer of the present invention has almost no shift in the same force range. Therefore, when the spectrometer of the present invention is tested, it can effectively eliminate the influence of the slight deformation of the spectrometer housing caused by external force on the position and intensity of the spectral spectrum, and has good spectral stability.

[0063] Meanwhile, it can be seen that the optical substrate 2 of the present invention is made of a substrate material with a low expansion coefficient, and a flexible fixing part 5 is arranged between the metal shell 1 and the optical substrate 2. In actual spectral testing, when subjected to external force collision, compared with the spectrometer of the traditional scheme, the overall deformation of the optical substrate 2 can be reduced, and the relative position changes of the slit 3, optical lens and photodetector 4 on the optical substrate 2 can be prevented, so it is beneficial to improve the stability of the spectral detection results, and at the same time, it is beneficial to improve the test accuracy of the spectrometer.

[0064] In summary, it can be seen that the main research and development purposes and beneficial effects of the invention are:

[0065] 1. The optical substrate 2 is manufactured using a high-strength and low-temperature deformation coefficient material (i.e., a substrate material with a low expansion coefficient) to avoid temperature changes causing changes in the relative positions of components in the optical system, thereby achieving no significant spectral wavelength fluctuations within a large temperature change range.

[0066] 2. The flexible fixing part 5 between the optical system and the instrument housing is used to prevent the deformation of the metal housing 1 caused by the force, which may cause the relative position change of the optical elements (i.e., optical lenses and related devices), thereby achieving the insensitivity of the spectral detection results to the external force on the instrument, and obtaining extremely high stability of the spectral detection results; at the same time, the defects of high brittleness, low impact resistance and poor machinability commonly existing in low temperature deformation coefficient materials are avoided, and the normal use and installation and fixation of the spectrometer are not affected.

[0067] 3. Compared with the prior art method of directly manufacturing the spectrometer structure using Invar alloy, although it can reduce the influence of external forces, it will bring about a significant increase in weight. The present invention uses a flexible fixing part to maintain the volume and weight of the spectrometer without significant changes, thus meeting the needs of existing application scenarios.

[0068] The implementation methods of the present invention are not limited to this. According to the above content of the present invention, using common technical knowledge and customary means in the field, without departing from the above basic technical ideas of the present invention, the present invention can also make other various forms of modification, replacement or combination, all of which fall within the scope of protection of the present invention.

Claims

1. A low temperature drift and high stability micro-spectrometer, characterized in that: It comprises a metal shell and an optical substrate, wherein the metal shell has an inner cavity and an entrance for a detected light beam; The optical substrate is arranged in the inner cavity of the metal shell, and there is a gap between the outer peripheral surface of the optical substrate and the inner wall of the inner cavity. A slit, a photoelectric detector and a plurality of optical lenses are arranged on the optical substrate. The slit is connected to the entrance of the detected light beam through a flexible optical waveguide. The light beam injected from the slit generates a corresponding spectrum through the optical lens, and the photoelectric detector is used to detect the spectrum. A flexible fixing piece is arranged on the outer peripheral surface of the optical substrate, and the flexible fixing piece is connected to the inner wall of the inner cavity; the optical substrate is made of a substrate material with a low expansion coefficient.

2. The low temperature drift and high stability micro-spectrometer according to claim 1, characterized in that: The flexible fixing member is a rubber pad, and the number of the rubber pads is multiple, and the multiple rubber pads are evenly spaced and distributed along the annular direction on the outer periphery of the optical substrate.

3. The low temperature drift and high stability micro-spectrometer according to claim 1, characterized in that: A gap between the optical substrate and the inner wall of the inner cavity is sealed with flexible glue, and the sealed and cured flexible glue forms the flexible fixing member.

4. The low temperature drift and high stability micro-spectrometer according to claim 1, characterized in that: The flexible fixing member adopts a spring pad, and the number of the spring pads is multiple, and the multiple spring pads are distributed at intervals along the annular direction on the outer periphery of the optical substrate.

5. The low temperature drift and high stability micro-spectrometer according to claim 1, characterized in that: The flexible fixing frame adopts an airbag, the airbag is in a ring shape, and the airbag is arranged on the outer peripheral surface of the optical substrate.

6. The low temperature drift and high stability micro-spectrometer according to claim 1, characterized in that: The substrate material is quartz, microcrystalline glass, alumina ceramics, silicon carbide or silicon nitride.

7. The low temperature drift and high stability micro-spectrometer according to claims 1 to 6, characterized in that: The optical lens includes one or more collimating lenses, beam splitting gratings or focusing lenses.

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