Spectrum detection module and confocal microscope

Abstract

The invention relates to a spectrum detection module and a confocal microscope. The spectrum detection module comprises a dispersion element and a first spectrum splitting device located on a light emitting surface of the dispersion element, the first spectrum splitting device specifically comprises a first imaging lens group, a first slit assembly, a first converging lens group and a first photoelectric detector which are sequentially arranged along a first optical axis from the light emitting surface of the dispersion element; the first slit assembly comprises a pair of first slit halves arranged at intervals in the direction perpendicular to the first optical axis and a first driving piece in driving connection with a first slit plate, and the first slit plate is used for moving in the arrangement direction under the action of the first driving piece. A first variable slit with variable width and / or position is formed on the exit pupil plane of the first imaging lens group, the entrance pupil plane of the first converging lens group coincides with the first variable slit, the first photoelectric detector is located on the exit pupil plane of the first converging lens group, and it can be understood that the arrangement direction is the same as the spectrum expansion direction.

Description

Technical Field

[0001] The present invention relates to the technical field of confocal microscopes, and particularly to a spectral splitting device, a multi-channel spectral detection module and a confocal microscope. Background Art

[0002] With the development of cell biology research, based on the application of confocal optical sectioning, researchers further require a confocal microscope with high spectral resolution. For the application requirements, the spectral splitting function can only be achieved by combining a spectral separation device. Spectral separation is often achieved by adding dispersive elements such as filters, gratings or prisms in the imaging optical path. Among them, the advantage of the filter is its low cost, but there are problems of uneven spectral bandwidth and light loss. The advantage of the grating is that the dispersion angle is uniform, but the light efficiency depends on the polarization direction of the incident light and there is still 20% light loss, and there is also more stray light. The prism has the best spectral range and light energy transmission efficiency among the three, and selecting a prism with total reflection characteristics can further improve the light efficiency. The only disadvantage is that the dispersion angle is uneven.

[0003] For the continuous spectral scanning of a confocal microscope, the existing optical path either adopts the method of rotating the dispersive element, which has high requirements for the rotating motor and engineering accuracy; or adopts the method of fixing the dispersive element, but it is difficult to balance the spectral resolution, dispersion angle uniformity and adjacent spectral overlap problems. Summary of the Invention

[0004] Based on the deficiencies that it is difficult to achieve high-resolution continuous spectral scanning or it is difficult to balance the spectral resolution, dispersion angle uniformity and adjacent spectral overlap problems in the existing confocal microscopes, it is necessary to provide a spectral detection module and a confocal microscope.

[0005] A spectral detection module includes a dispersive element and a first spectral splitting device located on the light-emitting surface of the dispersive element. The first spectral splitting device includes, in sequence along a first optical axis from the light-emitting surface:

[0006] A first imaging lens group;

[0007] A first slit assembly, including a pair of first slit plates arranged at intervals along a direction perpendicular to the first optical axis and a first driving member drivingly connected to the first slit plates. The first slit plates are used to move along the arrangement direction under the action of the first driving member to form a first variable slit with variable width and / or variable position on the exit pupil surface of the first imaging lens group;

[0008] A first converging lens group, the entrance pupil surface of the first converging lens group coinciding with the first variable slit; and

[0009] A first photodetector, located on the exit pupil surface of the first converging lens group.

[0010] With such a setting, the screening of the spectrum is achieved through the first variable slit, and a high resolution can still be ensured even when the accuracy of the driving motor is limited and the detection area of the first photodetector is limited, the cost is reduced, and the uneven dispersion angle can be adapted to ensure the authenticity of the spectrum detection result.

[0011] In one embodiment, the product of the total dispersion angle of the dispersion element and the focal length of the first imaging lens group is less than the stroke of the first variable slit, and the stepping accuracy of the first variable slit is greater than the product of the dispersion angle of the light rays within a wavelength difference range of 2 nm and the focal length of the first imaging lens group.

[0012] With such a setting, the step stroke of the first variable slit can cover the entire spectrum. After each step, the light rays that can pass through the first variable slit are mainly the light rays within the target spectrum range, ensuring the detection accuracy.

[0013] In one embodiment, the first imaging lens includes a first lens with a positive optical power and a second lens with a negative optical power arranged in sequence along the direction of the first optical axis. The second lens is glued to the first lens, and the focal length f1 of the first lens and the focal length f2 of the second lens satisfy:

[0014] 0.5 ≤ |f1 / f2| ≤ 1.5.

[0015] With such a setting, the spherical aberration is corrected by this lens group, so that most of the energy of the non-demand spectrum is filtered, ensuring the imaging contrast of the demand band.

[0016] In one embodiment, the first photodetector has a first receiving target surface that is a conjugate surface with the exit pupil surface of the first converging lens group.

[0017] With such a setting, the light rays within the target spectrum range of the first converging lens group can all be converged to the first receiving target surface of the first photodetector, making full use of the light energy and being beneficial to improving the spectrum detection accuracy.

[0018] In one embodiment, the ratio of the diameter of the exit pupil surface of the first converging lens group to the diameter of the first receiving target surface is less than 0.8.

[0019] With such a setting, the central area with higher detection accuracy on the first receiving target surface is utilized as much as possible, which is beneficial to further improving the spectrum resolution.

[0020] In one embodiment, the first slit plate further has a first reflecting surface that is inclined with respect to the first optical axis;

[0021] The spectral detection module further includes a second spectral splitting device and a third spectral splitting device respectively arranged corresponding to the two first reflecting surfaces. The second spectral splitting device is used to detect the spectrum in the short-wave band, and the third spectral splitting device is used to detect the spectrum in the long-wave band.

[0022] With such an arrangement, the multi-channel spectral synchronous scanning function is realized, which is beneficial to saving the detection time, improving the efficiency of spectral detection, and can significantly improve the generation speed of the scanned image in a confocal microscope.

[0023] In one embodiment, the second spectral splitting device includes a second imaging lens group, a second slit assembly, a second converging lens group, and a second photodetector arranged in sequence along the second optical axis. The second slit assembly includes a pair of second slit plates arranged at intervals in sequence along a direction perpendicular to the second optical axis and a second driving member drivingly connected to the second slit plates to form a second variable slit with variable width and / or variable position; and / or

[0024] The third spectral splitting device includes a third imaging lens group, a third slit assembly, a third converging lens group, and a third photodetector arranged in sequence along the third optical axis. The third slit assembly includes a pair of third slit plates arranged at intervals in sequence along a direction perpendicular to the third optical axis and a third driving member drivingly connected to the third slit plates to form a third variable slit with variable width and / or variable position.

[0025] With such an arrangement, the second spectral splitting device and the third spectral splitting device can also realize scanning, which facilitates combining the first driving member, the second driving member, and the third driving member into a driving assembly, facilitates unified control, and ensures the authenticity of spectral detection. The spatial occupation of the entire spectral detection module is small, which is convenient for integration into a confocal microscope.

[0026] In one embodiment, the product of the magnification of the second imaging lens and the stroke of the first variable slit is less than the stroke of the second variable slit, and the product of the magnification of the second imaging lens group and the step accuracy of the first variable slit is less than the step accuracy of the second variable slit; and / or

[0027] The product of the magnification of the third imaging lens group and the stroke of the first variable slit is less than the stroke of the third variable slit, and the product of the magnification of the third imaging lens group and the step accuracy of the first variable slit is less than the step accuracy of the third variable slit.

[0028] With such a setting, the shape of the imaging spot is also adjusted by the magnification factor. Especially in the second spectral splitting device for detecting short wavelengths, the image projected by the second converging lens group onto the second photodetector is synchronously magnified by magnifying the imaging spot, making full use of the second receiving target surface of the second photodetector, which is conducive to further improving the spectral resolution. In the third spectral splitting device, the magnification design of the third imaging lens group can further converge the spectrum in the long-wavelength band, avoiding the imaging on the third receiving target surface from exceeding the range.

[0029] In one embodiment, the first reflecting surface is parallel to the arrangement direction of the two first slit plates; the normal lines of the two first reflecting surfaces respectively face opposite sides of the first optical axis.

[0030] With such a setting, the light is reflected as much as possible in the direction perpendicular to the unfolding plane of the dispersed light, reducing the divergence of the light and avoiding the spectral distortion after reflection, which is conducive to improving the spectral detection accuracy.

[0031] This application also provides a confocal microscope, including:

[0032] The spectral detection module as described above; and

[0033] A confocal light-shearing main body, which is arranged on the incident surface of the dispersive element of the spectral detection module and is used to provide parallel light that faces the incident surface and has a divergence angle less than or equal to 0.1°.

[0034] With such a setting, by restricting the divergence angle of the parallel light, it is conducive to improving the spectral clarity of the light rays emerging from the dispersive element. Further, the spot diameter on the first slit plate is also small, which is conducive to improving the spectral resolution of the spectral detection module. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic structural diagram of a spectral detection module provided by this application;

[0036] Figure 2 It is a positional relationship diagram of light rays with wavelengths of 400 - 750 nm at the first slit assembly, the second slit assembly, and the third slit assembly in the Perin-Broca prism system;

[0037] Figure 3 It is a spot diagram of the first imaging lens group when the light wavelength is 400 nm;

[0038] Figure 4 It is a spot diagram of the first imaging lens group when the light wavelength is 750 nm;

[0039] Figure 5 It is a spot diagram of the second imaging lens group when the light wavelength is 400 nm;

[0040] Figure 6 The spot diagram of the second imaging lens group when the light wavelength is 750 nm;

[0041] Figure 7 It is a positional relationship diagram of light with wavelengths from 400 to 750 nm at the first slit assembly, the second slit assembly, and the third slit assembly in the reflection grating system.

[0042] Reference numerals:

[0043] 1, dispersion element; 2, first imaging lens group; 3, first slit assembly; 4, first converging lens group; 5, first photodetector; 6, second imaging lens group; 7, second slit assembly; 8, second converging lens group; 9, second photodetector; 10, third imaging lens group; 11, third slit assembly; 12, third converging lens; 13, third photodetector. Detailed implementation manners

[0044] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following describes the detailed implementation manners of the present invention with reference to the accompanying drawings. Many specific details are set forth in the following description to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0045] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0046] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0047] In the present invention, unless otherwise clearly specified or limited, terms such as "installed", "connected", "linked", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] In the present invention, unless otherwise clearly specified or limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0049] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are only for the purpose of illustration and do not represent the only implementation.

[0050] With the development of cell biology research, based on the application of confocal optical sectioning, researchers further demand a confocal microscope with high spectral resolution. To meet the application requirements, the spectral splitting function can only be achieved by combining a spectral separation device. Spectral separation is often achieved by adding dispersion elements such as filters, gratings or prisms in the imaging optical path. The advantage of the filter is its low cost, but there are problems of uneven spectral bandwidth and light loss. The advantage of the grating is that the dispersion angle is uniform, but the light efficiency depends on the polarization direction of the incident light and there is still 20% light loss, and there is also more stray light. While the prism has the best spectral range and light energy transmission efficiency among the three, and selecting a prism with total reflection characteristics can further improve the light efficiency. The only disadvantage is that the dispersion angle is uneven.

[0051] For the continuous spectral scanning of a confocal microscope, the existing optical path either adopts the method of rotating the dispersion element, which has high requirements for the rotating motor and engineering accuracy; or adopts the method of fixing the dispersion element, but it is difficult to balance the spectral resolution, dispersion angle uniformity and adjacent spectral overlap problems.

[0052] Based on this, it is necessary to provide a spectral detection module and a confocal microscope that can achieve continuous scanning, have a relatively high spectral resolution, and have a relatively low cost.

[0053] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of a spectral detection module in an embodiment provided by this application. In an implementation manner provided by this application, the spectral detection module includes a dispersion element 1 and a first spectral splitting device located on the light-emitting surface of the dispersion element 1. Specifically, the first spectral splitting device includes: a first imaging lens group 2, a first slit assembly 3, a first converging lens group 4, and a first photodetector 5 that are sequentially arranged along a first optical axis from the light-emitting surface of the dispersion element 1. Specifically, the first slit assembly 3 includes a pair of first slit halves arranged at intervals in a direction perpendicular to the first optical axis and a first driving member drivingly connected to the first slit plate. The first slit plate is used to move along the arrangement direction under the action of the first driving member to form a first variable slit with a variable width and / or a variable position on the exit pupil surface of the first imaging lens group 2. The entrance pupil surface of the first converging lens group 4 coincides with the first variable slit, and the first photodetector 5 is located on the exit pupil surface of the first converging lens group 4. It can be understood that this arrangement direction is the same as the spectral unfolding direction.

[0054] Based on the structure of the above optical path detection module, the light rays emitted from the dispersion element 1 will form an image on the first slit plate after passing through the first imaging lens group 2, specifically an imaging light spot with a diameter smaller than the Airy disk. This light spot carries the spectral information of the light rays emitted from the dispersion element 1. The first variable slit is used to transmit the light rays of the target bandwidth spectrum. The light rays passing through the first variable slit will further pass through the first converging lens and then reach the first photodetector 5, thereby completing the detection of the target bandwidth spectrum; by using the first driving member to adjust the position of the first variable slit, the detection of the target bandwidth spectrum at different positions on this light spot is achieved, that is, the spectral splitting is realized; by using the first driving member, the width of the first variable slit can also be adjusted, which can not only adjust the accuracy of spectral splitting and realize the adjustment of spectral resolution, but also adapt to the uneven dispersion angle of the dispersion element 1 to avoid distortion of the spectral detection result. For example, when the dispersion element 1 uses a prism, the dispersion angle corresponding to the spectrum of a unit bandwidth gradually increases from the short wave to the long wave. Design the width of the first variable slit according to the Cauchy dispersion formula. When the first variable slit moves from the short wavelength band to the long wavelength band of the spectrum, the width of the first variable slit also gradually increases.

[0055] In summary, the present application realizes the screening of the spectrum through the first variable slit. Even when the accuracy of the driving motor is limited and the detection area of the first photodetector 5 is limited, a high resolution can still be ensured, the cost is reduced, and the uneven dispersion angle can be adapted to ensure the authenticity of the spectrum detection result. In addition, in the present application, the positions of the dispersion element 1, the first imaging lens, the first converging lens, and the first photodetector 5 remain unchanged, and the optical path is stable. This not only facilitates assembly and reduces the influence of assembly errors on the detection structure, but also is conducive to realizing miniaturized design, providing a structural basis for realizing multi-channel spectrum detection.

[0056] With the development of confocal microscopes, researchers also require multi-channel spectrum synchronous scanning to improve the efficiency of spectrum analysis. Only imaging optical path splitting and synchronous acquisition can achieve physical multi-channel synchronous scanning. In the prior art, optical fibers are usually used to achieve physical splitting, but this requires multiple dispersion elements 1 to be equipped, and there is optical loss in optical fiber transmission. Optical fiber splitting also disperses the optical energy, which requires a photodetector with higher precision and higher cost.

[0057] Based on the above problems, in an embodiment provided by the present application, the spectrum detection module further includes a second spectrum splitting device and / or a third spectrum splitting device. The first slit plate is further provided with a first reflecting surface arranged obliquely to the first optical axis, and the two first reflecting surfaces respectively correspond to the second spectrum splitting device and the third spectrum splitting device. Splitting the light at the first variable slit makes full use of the energy of the light spot and realizes multi-channel spectrum detection. The first reflecting surface arranged obliquely to the first optical axis avoids position interference between the first spectrum splitting device and the second spectrum splitting device or the third spectrum splitting device. Optionally, in order to reduce the divergence of the reflected light at the first reflecting surface in the spectrum unfolding direction, the first reflecting surface is parallel to the arrangement direction of the two first slit plates. On this basis, in order to facilitate the simultaneous arrangement of the second spectrum splitting device and the third spectrum splitting device, the normal lines of the two first reflecting surfaces face both sides of the first optical axis, that is, as Figure 1 shown in, the second spectrum splitting device is located above the first optical axis, and the third spectrum splitting device is located below the first optical axis.

[0058] Optionally, in an embodiment provided by the present application, the structures of the second spectral splitting device and the third spectral splitting device are the same as that of the first spectral splitting device, that is: the second spectral splitting device includes a second imaging lens group 6, a second slit assembly 7, a second converging lens group 8 and a second photodetector 9 arranged in sequence along the second optical axis. The second slit assembly 7 includes a pair of second slit plates arranged at intervals in sequence along a direction perpendicular to the second optical axis and a second driving member drivingly connected to the second slit plates to form a second variable slit with variable width and / or variable position; the third spectral splitting device includes a third imaging lens group 10, a third slit assembly 11, a third converging lens group 12 and a third photodetector 13 arranged in sequence along the third optical axis. The third slit assembly 11 includes a pair of third slit plates arranged at intervals in sequence along a direction perpendicular to the third optical axis and a third driving member drivingly connected to the third slit plates to form a third variable slit with variable width and / or variable position. In this way, the first driving member, the second driving member and the third driving member can be combined into a driving assembly, which facilitates unified control and ensures the authenticity of spectral detection. The spatial occupation of the entire spectral detection module is small, which facilitates integration into a confocal microscope. Optionally, in an embodiment provided by the present application, the first photodetector 5, the second photodetector 9 and the third photodetector 13 respectively adopt photomultiplier tubes.

[0059] Considering that the spot sizes of light rays with different wavelengths on the first slit plate are different, in order to make full use of the receiving target surface of the photodetector and improve the accuracy and resolution of spectral detection, optionally, in an embodiment provided by the present application, the second imaging lens group 6 and the third imaging lens group 10 respectively have a certain magnification, and the magnification is determined according to the stroke and accuracy of the variable slit length. Specifically, taking the spectrum corresponding to the short-wave band of the second spectral detection module and the spectrum corresponding to the long-wave band of the third spectral detection module as an example: the product of the magnification of the second imaging lens group 6 and the stroke of the first variable slit < the stroke of the second variable slit, and the product of the magnification of the second imaging lens group 6 and the step accuracy of the first variable slit < the step accuracy of the second variable slit. Similarly, the product of the magnification of the third imaging lens group 10 and the stroke of the first variable slit is less than the stroke of the third variable slit, and the product of the magnification of the third imaging lens group 10 and the step accuracy of the first variable slit is less than the step accuracy of the third variable slit.

[0060] Optionally, considering the accuracy of the spectral detection module, in an implementation provided by the present application, the product of the total dispersion angle of the dispersion element 1 and the focal length of the first imaging lens group 2 is less than the stroke of the first variable slit, and the stepping accuracy of the first variable slit is greater than the product of the dispersion angle of the light rays within a wavelength difference range of 2 nm and the focal length of the first imaging lens group 2. In this way, the stepping stroke of the first variable slit can cover the entire spectrum. After each step, the light rays that can pass through the first variable slit are mainly the light rays within the target spectral range, ensuring the detection accuracy.

[0061] Optionally, in an implementation provided by the present application, the first imaging lens includes a first lens with a positive optical power and a second lens with a negative optical power arranged in sequence along the first optical axis direction. The second lens is glued to the first lens, and the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: 0.5 ≤ |f1 / f2| ≤ 1.5. By correcting the spherical aberration through this lens group, most of the energy of the non-required spectrum is filtered, ensuring the imaging contrast of the required wavelength band.

[0062] Optionally, in an implementation provided by the present application, the first photodetector 5 has a first receiving target surface that is conjugate to the exit pupil surface of the first converging lens group 4. The light rays within the target spectral range passing through the first converging lens group 4 can all be converged onto the first receiving target surface of the first photodetector 5, making full use of the light energy and being beneficial to improving the spectral detection accuracy. Further, the ratio of the diameter of the exit pupil surface of the first converging lens group 4 to the diameter of the first receiving target surface is less than 0.8, making the best use of the central area with higher detection accuracy on the first receiving target surface, which is beneficial to further improving the spectral resolution.

[0063] The present application also provides a confocal microscope, including a spectral detection module and a confocal optical sectioning body. The confocal optical sectioning body is arranged on the incident surface of the dispersion element 1 and is used to provide parallel light directed towards the incident surface with a divergence angle less than or equal to 0.1°. By restricting the divergence angle of the parallel light, it is beneficial to improve the spectral clarity of the light rays exiting the dispersion element 1. Further, the spot diameter on the first slit plate is also small, which is beneficial to improving the spectral resolution of the spectral detection module.

[0064] According to the spectral detection requirements of the confocal microscope: for the spectrum with a wavelength range satisfying 400nm to 750nm, the dispersive element 1 can adopt a Perrin-Broca prism (N-BK7), an equilateral dispersive prism, a reflection grating, and a prism-grating-prism (PGP) beam splitter. Among them, the dispersive spectrum of the Perrin-Broca prism covers the ultraviolet to infrared bands with a relatively wide range, which can reduce the non-linearity of the incident light dispersion within the required wavelength range of 400nm to 750nm; the manufacturing cost of the equilateral dispersive prism is lower than that of the Perrin-Broca prism, but its ability to control the direction and polarization state of the light beam is weak; the reflection grating has good dispersion uniformity. When used in combination with the spectral detection module, the width of the first variable slit of the spectral detection module can be a fixed value, but there is a certain optical transmission loss; due to the use of a volume phase holographic transmission grating, the prism-grating-prism (PGP) beam splitter can obtain a high diffraction efficiency. By selecting the prism material and controlling the angle, the coaxiality of the incident and outgoing light beams and the non-linearity correction of the dispersion can be achieved, which is convenient for system alignment and band selection.

[0065] In a specific embodiment, taking the Perrin-Broca prism as the dispersive element 1 as an example, the spectral detection module will be introduced in detail below.

[0066] Based on the structure of the spectral detection module provided in this application, the relationship between the movement amount and the width change amount of the first variable slit and the spectrum is based on the Cauchy dispersion formula to give the theoretical value. In the formula, n is the refractive index of the medium, λ is the incident wavelength, A, B, and C are medium-related constants, and the actual spectrum calibration still requires measurement by a spectrometer. According to this formula, the corresponding values of the angular variable per unit wavelength at the endpoints of the wavelength range can be calculated. This angular variable corresponds to the width of the first variable slit. For example, for the wavelength range of 400nm to 750nm and the prism material being N-BK7, this term in the dispersion formula can be ignored This item. The value of the dispersion angular variable corresponding to 1nm unit wavelength at 750nm is more than twice that at 400nm. Then, according to the difference in the dispersion angular variables, the width change amount of the first variable slit in each step is allocated. In this way, the spectral detection accuracy is converted into the mechanical control accuracy of the driving motor, which facilitates the design. The spectral detection module calibrated by the spectrometer can quickly detect the spectrum within the required wavelength range of 400nm to 750nm. In this embodiment, after the broadband spectral beam is split by the Perrin-Broca prism 1 and the first imaging lens group 2, at the surface of the first slit assembly 3, the light interval between 749 and 750nm is 8um, the interval between 748 and 750nm is 17um, and the interval between 400 and 750nm is 7.42mm. The magnification ratios of the first and second imaging lens groups are 1. According to the above parameters, the step accuracy of each slit assembly needs to be within the range of 8 to 17um, and the stroke is greater than 7.42mm. Figure 2It is the positional relationship of each wavelength on the surfaces of the first slit assembly 3, the second slit assembly 7, and the third slit assembly 11, and the slit movement can be controlled according to the fitting formula.

[0067] The spot diameter on the first slit plate is less than half of the step accuracy of the first variable slit, and the diameter of the first receiving target surface is 5 mm. Even when the accuracy of the driving motor is limited and the receiving area of the first receiving target surface is also limited, this spectral detection module can still achieve a spectral resolution of 2 nm.

[0068] In multi-channel spectral detection, the second photodetector 9, the first photodetector 5, and the third photodetector 13 are respectively used to collect the spectral energy in three bands of 400 nm - 499 nm, 400 nm - 750 nm, and 500 nm - 750 nm. Among them, the light wavelength of the corresponding band of the second spectral detection module is smaller, the spectral resolution is higher, and the contrast of the detection band is better. As Figures 3 to 6 shown, Figure 3 is the spot diagram of the first imaging lens group 2 when the light wavelength is 400 nm, Figure 4 is the spot diagram of the first imaging lens group 2 when the light wavelength is 750 nm, Figure 5 is the spot diagram of the second imaging lens group 6 when the light wavelength is 400 nm, Figure 6 is the spot diagram of the second imaging lens group 6 when the light wavelength is 750 nm. As shown in the figure, the spot diffraction dispersion spot of the second imaging lens is smaller, the energy concentration is higher, and the spectral resolution is also higher. It should be noted that the band classification of the above three photodetectors is only used for distinction in multi-channel spectral detection. It can be understood that in single-channel spectral detection, all three optical paths can collect the spectral energy in the 400 nm - 750 nm band. Figures 3 to 6 In it, the RMS radius (Root Mean Square Radius) is a commonly used parameter to describe the transverse size of a spot or a light beam, and it is of great significance especially in laser optics and beam quality analysis. It quantifies the width of the light beam by calculating the second moment of the light intensity distribution.

[0069] Exemplarily, when the dispersion element 1 is a reflection grating, considering the grating dispersion, in multi-channel spectral detection, the incident light wavelength range of the second imaging lens group 6 is changed to 400 nm - 574 nm, and the incident light wavelength range of the third imaging lens group 10 is changed to 575 nm - 750 nm. To control the system size, the focal length of the first imaging lens 2 is set to be less than 200 mm, and the diffraction angle of 2 nm is less than 0.012°. As Figure 7As shown, the light distributions of each wavelength at the first, second, and third slits are uniform. At the surface of the first slit assembly 3, the interval between 748 - 750 nm is 42 um, and the interval between 400 - 750 nm is 7.42 mm. The magnification ratios of the first and second imaging lens groups are 1. According to the above parameters, the step accuracy of each slit assembly is reduced. It only needs to be within the range of 21 - 42 um, and the travel distance is greater than 7.42 mm. The spherical aberration is optimized by combining positive and negative lenses, so that the radius of the imaging spot (GEO) on each slit plate is smaller than the radius of the Airy disk. After adjustment and optimization, the spectral resolution of this spectral detection module can also reach a detection accuracy of 2 nm.

[0070] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0071] The above embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be understood as a limitation to the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of this invention patent should be subject to the appended claims.

Claims

1. A spectral detection module, characterized in that, Comprising a dispersion element and a first spectral splitting device located on the light-emitting surface of the dispersion element, the first spectral splitting device includes, in sequence along a first optical axis from the light-emitting surface: A first imaging lens group; A first slit assembly, including a pair of first slit plates arranged at intervals in a direction perpendicular to the first optical axis and a first driving member drivingly connected to the first slit plates, the first slit plates being adapted to move along the arrangement direction under the action of the first driving member to form a first variable slit with variable width and / or variable position on the exit pupil surface of the first imaging lens group; A first converging lens group, the entrance pupil surface of the first converging lens group coinciding with the first variable slit; And A first photodetector, located on the exit pupil surface of the first converging lens group.

2. The spectral detection module according to claim 1, characterized in that The product of the total dispersion angle of the dispersion element and the focal length of the first imaging lens group is less than the travel of the first variable slit, and the step accuracy of the first variable slit is greater than the product of the dispersion angle of light within a wavelength difference range of 2 nm and the focal length of the first imaging lens group.

3. The spectral detection module according to claim 1, wherein The first imaging lens includes a first lens with a positive optical power and a second lens with a negative optical power arranged in sequence along the first optical axis direction, the second lens being cemented to the first lens, and the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: 0.5 ≤ |f1 / f2| ≤ 1.

5.

4. The spectral detection module according to claim 1, characterized in that, The first photodetector has a first receiving target surface that is conjugate to the exit pupil surface of the first converging lens group.

5. The spectral detection module according to claim 4, characterized in that The ratio of the diameter of the exit pupil surface of the first converging lens group to the diameter of the first receiving target surface is less than 0.

8.

6. The spectral detection module according to any one of claims 1 to 5, characterized in that The first slit plate further has a first reflecting surface arranged obliquely to the first optical axis; The spectral detection module further includes a second spectral splitting device and a third spectral splitting device respectively arranged corresponding to the two first reflecting surfaces, the second spectral splitting device being used to detect the spectrum of the short-wave band, and the third spectral splitting device being used to detect the spectrum of the long-wave band.

7. The spectral detection module according to claim 6, wherein The second spectral splitting device includes a second imaging lens group, a second slit assembly, a second converging lens group, and a second photodetector arranged in sequence along a second optical axis, the second slit assembly including a pair of second slit plates arranged at intervals in a direction perpendicular to the second optical axis and a second driving member drivingly connected to the second slit plates to form a second variable slit with variable width and / or variable position; and / or The third spectral splitting device includes a third imaging lens group, a third slit assembly, a third converging lens group, and a third photodetector arranged in sequence along a third optical axis, the third slit assembly including a pair of third slit plates arranged at intervals in a direction perpendicular to the third optical axis and a third driving member drivingly connected to the third slit plates to form a third variable slit with variable width and / or variable position.

8. The spectral detection module according to claim 7, characterized in that The product of the magnification of the second imaging lens and the travel of the first variable slit is less than the travel of the second variable slit, and the product of the magnification of the second imaging lens group and the step accuracy of the first variable slit is less than the step accuracy of the second variable slit; and / or The product of the magnification of the third imaging lens group and the stroke of the first variable slit is less than the stroke of the third variable slit, and the product of the magnification of the third imaging lens group and the step accuracy of the first variable slit is less than the step accuracy of the third variable slit.

9. The spectral detection module according to claim 6, wherein The first reflecting surface is parallel to the arrangement directions of the two first slit plates; the normal lines of the two first reflecting surfaces respectively face opposite sides of the first optical axis.

10. A confocal microscope, characterized in that, Comprising: The spectral detection module according to any one of claims 1-9; and A confocal optical sectioning body, disposed on the incident surface of the dispersive element of the spectral detection module and configured to provide parallel light that is directed toward the incident surface and has a divergence angle less than or equal to 0.1°.

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