Multi-channel diffraction spectrum light splitting system based on volume holographic diffraction grating

Abstract

The multichannel diffraction spectrum beam splitting system comprises a wide-spectrum light source, a beam splitter connected with the wide-spectrum light source, at least one channel light path connected with the beam splitter and a computer connected with the channel light path, and the volume holographic diffraction grating serving as a dispersion element is arranged on the channel light path. The channel light path sequentially comprises a filter, a collimator objective, a grating, an imaging objective and a line-scan digital camera in the advancing direction of the light path, the filter is connected with the beam splitter, and the line-scan digital camera is connected with the computer. According to the method, a design scheme of integrating a collimating objective lens, a volume holographic diffraction grating and an imaging objective lens is utilized to construct a spectral dispersion light splitting model of which the spectral resolution is increased step by step, so that wide-spectrum fine dispersion light splitting covering visible-near infrared bands is realized. A volume holographic diffraction grating serving as a dispersion element is arranged on a channel light path, ghost lines can be effectively eliminated, the stray light level can be effectively reduced, and ultrahigh diffraction efficiency is provided.

Description

Technical Field

[0001] The present invention belongs to the field of optical imaging, and relates to a multi-channel diffraction spectral splitting system based on a volume holographic diffraction grating for wide-spectrum fine dispersion splitting covering the visible-near infrared band. Background Art

[0002] Common spectral splitting methods include dispersive, interferometric, filter-based, and binary element and filtering-based spectral splitting methods. Among them, dispersive spectral splitting methods mostly use prisms or blazed gratings for spectral splitting. Due to the uneven dispersion of a single material in the prism, the spectral resolution is non-linear. In the manufacturing process of blazed gratings, periodic errors or scribing mistakes may occur, so it is easy to generate ghost lines (i.e., optical artifacts caused by periodic errors) and high stray light phenomena. This may affect the clarity and accuracy of spectral images, and it is sensitive to wavelength and incident light angle, and the diffraction efficiency may change with the change of wavelength and incident angle, affecting the stability of spectral splitting. VPH gratings can achieve a very high line density, thus providing high resolution and high diffraction efficiency in a wide spectral range. In some cases, its diffraction efficiency can even reach more than 99%, far higher than that of traditional gratings. Its special structural design can effectively eliminate ghost lines and reduce the level of stray light, thereby providing a clearer and more accurate spectral image.

[0003] The wavelength bands targeted by traditional spectral splitting methods can generally be divided into ultraviolet, visible, or near infrared bands, and none of them can achieve spectral splitting for a relatively wide spectral band. However, in the present invention, a beam splitter is used to divide a wide-spectrum light source into three optical path channels, and different collimating objectives and imaging objectives are designed for different spectral ranges of each channel to eliminate chromatic aberration, realizing high-precision dispersion splitting with a wide spectral band and high throughput. Summary of the Invention

[0004] The problem to be solved by the present invention is to provide a multi-channel diffraction spectral splitting system based on a volume holographic diffraction grating, and use an integrated design scheme of a collimating objective, a volume holographic diffraction grating, and an imaging objective to construct a spectral dispersion splitting model with gradually increasing spectral resolution, realizing wide-spectrum fine dispersion splitting covering the visible-near infrared band.

[0005] To solve the above technical problems, the technical solution of the present invention is: a multi-channel diffraction spectral splitting system based on a volume holographic diffraction grating, and its innovation lies in: the multi-channel diffraction spectral splitting system based on a volume holographic diffraction grating includes a wide-spectrum light source, a beam splitter connected to the wide-spectrum light source, at least one channel optical path respectively connected to the beam splitter, and a computer connected to the channel optical path, and a volume holographic diffraction grating serving as a dispersion element is arranged on the channel optical path; The channel optical path sequentially includes a filter, a collimating objective lens, a grating, an imaging objective lens, and a linear array camera along the forward direction of the optical path. The filter is connected to the beam splitter, and the linear array camera is connected to the computer.

[0006] Preferably, the beam splitter is provided with an input end connected to the broadband light source and an output end connected to the channel optical path, and the number of output ends is the same as the number of channel optical paths.

[0007] Preferably, the spectral range of the broadband light source is from 350 nm to 1100 nm.

[0008] Preferably, three channel optical paths are arranged in parallel between the beam splitter and the computer on the multi-channel diffraction spectral splitting system based on volume holographic diffraction gratings, including a first channel, a second channel, and a third channel. The beam splitter is respectively provided with a first output end, a second output end, and a third output end connected to the first channel, the second channel, and the third channel. The first channel, the second channel, and the third channel are respectively connected to the computer; volume holographic diffraction gratings serving as dispersion elements are arranged on the first channel, the second channel, and the third channel.

[0009] Preferably, the first channel sequentially includes a first filter, a first collimating objective lens, a first grating, a first imaging objective lens, and a first linear array camera along the forward direction of the optical path. The spectral range of the first channel is from 350 nm to 880 nm, the filtering range of the first filter is from 350 nm to 880 nm. The first collimating objective lens and the first imaging objective lens are both composed of four groups of lenses sequentially distributed along the forward direction of the optical path. The first grating is a volume holographic diffraction grating, and the spectral diffraction range of the first grating is from 350 nm to 880 nm.

[0010] Preferably, the included angle between the light source incident direction of the first grating and the end face of the first grating facing the light source is between 75° and 85°; The first collimating objective lens sequentially includes a first plano-convex lens, a first concave-convex lens, a second concave-convex lens, and a first convex lens along the forward direction of the optical path; The first imaging objective lens sequentially includes a second convex lens, a third concave-convex lens, a fourth concave-convex lens, and a third convex lens along the forward direction of the optical path.

[0011] Preferably, the second channel sequentially includes a second filter, a second collimating objective lens, a second grating, a second imaging objective lens, and a second linear array camera along the optical path advancing direction. The spectral range of the second channel is from 870 nm to 1050 nm. The filtering range of the second filter is from 870 nm to 1050 nm. The second collimating objective lens is composed of two groups of lenses sequentially distributed along the optical path advancing direction. The second imaging objective lens is composed of three groups of lenses sequentially distributed along the optical path advancing direction. The second grating is a volume holographic diffraction grating as a dispersion element. The spectral diffraction range of the second grating is from 870 nm to 1050 nm.

[0012] Preferably, the included angle between the light source incident direction of the second grating and the end face of the second grating facing the light source is between 65° and 80°; The second collimating objective lens sequentially includes a second plano-concave lens and a second plano-convex lens along the optical path advancing direction; The second imaging objective lens sequentially includes a fourth convex lens, a bi-concave lens, and a fifth convex lens along the optical path advancing direction.

[0013] Preferably, the third channel sequentially includes a third filter, a third collimating objective lens, a third grating, a third imaging objective lens, and a third linear array camera along the optical path advancing direction. The spectral range of the third channel is from 1040 nm to 1100 nm. The filtering range of the third filter is from 1040 nm to 1100 nm. Both the third collimating objective lens and the third imaging objective lens are composed of two groups of lenses sequentially distributed along the optical path advancing direction. The third grating is a volume holographic diffraction grating as a dispersion element. The spectral diffraction range of the third grating is from 1040 nm to 1100 nm.

[0014] Preferably, the included angle between the light source incident direction of the third grating and the end face of the third grating facing the light source is between 45° and 65°; The third collimating objective lens sequentially includes a third plano-concave lens and a third plano-convex lens along the optical path advancing direction; The third imaging objective lens sequentially includes a fourth plano-convex lens and a fourth plano-concave lens along the optical path advancing direction.

[0015] The advantages of the present invention are as follows: By adopting the above system, which mainly consists of a broadband light source, a beam splitter, a first channel, a second channel, a third channel, and a computer, and using an integrated design scheme of a collimating objective lens, a volume holographic diffraction grating, and an imaging objective lens, a spectral dispersion spectroscopy model with gradually increasing spectral resolution is constructed to achieve fine spectral dispersion spectroscopy in a wide spectral band covering the visible-near infrared band. Compared with the prior art, this system uses a volume holographic diffraction grating as a dispersion element, and its ultra-high diffraction efficiency lays a foundation for providing clearer and more accurate spectral images. A three-channel spectral dispersion spectroscopy model with gradually increasing spectral resolution is constructed to achieve high-precision spectral spectroscopy in an ultra-wide spectral band. Brief Description of the Drawings

[0016] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0017] Figure 1 It is a schematic structural diagram of a multi-channel diffraction spectral splitting system based on a volume holographic diffraction grating in an embodiment of the present invention.

[0018] Figure 2 It is a schematic diagram of the optical path of the first channel in a multi-channel diffraction spectral splitting system based on a volume holographic diffraction grating in an embodiment of the present invention.

[0019] Figure 3 It is a schematic diagram of the optical path of the second channel in a multi-channel diffraction spectral splitting system based on a volume holographic diffraction grating in an embodiment of the present invention.

[0020] Figure 4 It is a schematic diagram of the optical path of the third channel in a multi-channel diffraction spectral splitting system based on a volume holographic diffraction grating in an embodiment of the present invention.

[0021] Figure 5 It is a schematic structural diagram of a beam splitter in a multi-channel diffraction spectral splitting system based on a volume holographic diffraction grating in an embodiment of the present invention.

[0022] In the figure: 1 - broad-spectrum light source, 2 - beam splitter, 200 - input end, 201 - first output end, 202 - second output end, 203 - third output end, 3 - first channel, 31 - first filter, 32 - first collimating objective lens, 321 - first plano-convex lens, 322 - first concave-convex lens, 323 - second concave-convex lens, 324 - first convex lens, 33 - first grating, 34 - first imaging objective lens, 341 - second convex lens, 342 - third concave-convex lens, 343 - fourth concave-convex lens, 344 - third convex lens, 35 - first linear array camera, 4 - second channel, 41 - second filter, 42 - second collimating objective lens, 421 - second plano-concave lens, 422 - second plano-convex lens, 43 - second grating, 44 - second imaging objective lens, 441 - fourth convex lens, 442 - double concave lens, 443 - fifth convex lens, 45 - second linear array camera, 5 - third channel, 51 - third filter, 52 - third collimating objective lens, 521 - third plano-concave lens, 522 - third plano-convex lens, 53 - third grating, 54 - third imaging objective lens, 541 - fourth plano-convex lens, 542 - fourth plano-concave lens, 55 - third linear array camera, 6 - computer. Specific Embodiments

[0023] In conjunction with Figure 1As shown in the figure, the multi-channel diffraction spectral splitting system based on a volume holographic diffraction grating of the present invention includes a broadband light source 1, a beam splitter 2 connected to the broadband light source 1, at least one channel optical path respectively connected to the beam splitter 2, and a computer 6 connected to the channel optical path. A volume holographic diffraction grating serving as a dispersion element is provided on the channel optical path. The channel optical path sequentially includes a filter, a collimating objective lens, a grating, an imaging objective lens, and a linear array camera along the forward direction of the optical path. The filter is connected to the beam splitter 2, and the linear array camera is connected to the computer 6. By adopting the above spectral splitting system, using the integrated design scheme of the collimating objective lens, the volume holographic diffraction grating, and the imaging objective lens, a spectral dispersion splitting model with gradually increasing spectral resolution is constructed to achieve fine dispersion splitting of a broadband spectrum covering the visible-near infrared band.

[0024] An input end 200 connected to the broadband light source 1 and an output end connected to the channel optical path are provided on the beam splitter 2 of the present invention, and the number of output ends is the same as the number of channel optical paths. Three channel optical paths are provided side by side between the beam splitter 2 and the computer 6 on the multi-channel diffraction spectral splitting system based on a volume holographic diffraction grating, including a first channel 3, a second channel 4, and a third channel 5. First output end 201, second output end 202, and third output end 203 connected to the first channel 3, the second channel 4, and the third channel 5 are respectively provided on the beam splitter 2. The first channel 3, the second channel 4, and the third channel 5 are respectively connected to the computer 6; volume holographic diffraction gratings serving as dispersion elements are provided on the first channel 3, the second channel 4, and the third channel 5. The input end 200 is connected to the broadband light source 1 and serves as the total input of the system. The first output end 201 is connected to the first channel 3 and serves as the dispersion photon sub-system of the first band. The second output end 202 is connected to the second channel 4 and serves as the dispersion photon sub-system of the second band. The third output end 203 is connected to the third channel 5 and serves as the dispersion photon sub-system of the third band. The first channel 3, the second channel 4, and the third channel 5 are connected to the computer 6 to collect the spectral information detected by all sub-systems into the computer 6 to complete high-precision dispersion splitting of an ultra-wideband spectrum. The spectral range of the broadband light source 1 is 350 nm to 1100 nm, covering the visible and near-infrared bands. Compared with the prior art, the system uses a volume holographic diffraction grating as a dispersion element, and its ultra-high diffraction efficiency lays a foundation for providing clearer and more accurate spectral images, constructs a three-channel spectral dispersion splitting model with gradually increasing spectral resolution, and realizes high-precision spectral splitting of an ultra-wideband spectrum.

[0025] As Figure 2As shown in the figure, the first channel 3 sequentially includes a first filter 31, a first collimating objective lens 32, a first grating 33, a first imaging objective lens 34, and a first linear array camera 35 along the optical path advancing direction. The spectral range of the first channel 3 is from 350 nm to 880 nm. The filtering range of the first filter 31 is from 350 nm to 880 nm. Both the first collimating objective lens 32 and the first imaging objective lens 34 are composed of four groups of lenses sequentially distributed along the optical path advancing direction. The first grating 33 is a volume holographic diffraction grating, and the spectral diffraction range of the first grating 33 is from 350 nm to 880 nm. The included angle between the light source incident direction of the first grating 33 and the end face of the first grating 33 facing the light source is between 75° and 85°; the first collimating objective lens 32 sequentially includes a first plano-convex lens 321, a first concave-convex lens 322, a second concave-convex lens 323, and a first convex lens 324 along the optical path advancing direction; the first imaging objective lens 34 sequentially includes a second convex lens 341, a third concave-convex lens 342, a fourth concave-convex lens 343, and a third convex lens 344 along the optical path advancing direction. Since the spectral width of the first channel 3 is 530 nm and the spectral width is relatively wide, the aberration elimination using ordinary double-glued lenses is relatively large. Therefore, four-piece separated lenses are selected as the collimating and imaging objective lenses. The type of the first grating 33 is volume holographic diffraction and its optimal spectral diffraction is from 350 nm to 880 nm, ensuring the highest diffraction efficiency.

[0026] As Figure 3As shown in the figure, the second channel 4 successively includes a second filter 41, a second collimating objective lens 42, a second grating 43, a second imaging objective lens 44, and a second linear array camera 45 along the light path advancing direction. The spectral range of the second channel 4 is from 870 nm to 1050 nm. The filtering range of the second filter 41 is from 870 nm to 1050 nm. The second collimating objective lens 42 consists of two groups of lenses successively distributed along the light path advancing direction. The second imaging objective lens 44 consists of three groups of lenses successively distributed along the light path advancing direction. The second grating 43 is a volume holographic diffraction grating, and the spectral diffraction range of the second grating 43 is from 870 nm to 1050 nm. The included angle between the light source incident direction of the second grating 43 and the end face of the second grating 43 facing the light source is between 65° and 80°. The second collimating objective lens 42 successively includes a second plano-concave lens 421 and a second plano-convex lens 422 along the light path advancing direction. The second imaging objective lens 44 successively includes a fourth convex lens 441, a bi-concave lens 442, and a fifth convex lens 443 along the light path advancing direction. The spectral range of the above-mentioned second channel 4 is from 870 nm to 1050 nm, and the filtering range of the second filter 41 is from 870 nm to 1050 nm, ensuring that the light from 870 nm to 1050 nm passes through and making full use of the energy input by the light source. A doublet lens is used as the collimating lens, and a three-piece separated objective lens is used as the imaging lens to effectively control the chromatic aberration of the system. The type of the second grating 43 is volume holographic diffraction and its optimal spectral diffraction is from 870 nm to 1050 nm, and the grating line density of the second grating 43 can be the same as or different from that of the first grating 33.

[0027] As Figure 4 shown in the figure, the third channel 5 successively includes a third filter 51, a third collimating objective lens 52, a third grating 53, a third imaging objective lens 54, and a third linear array camera 55 along the light path advancing direction. The spectral range of the third channel 5 is from 1040 nm to 1100 nm. The filtering range of the third filter 51 is from 1040 nm to 1100 nm. Both the third collimating objective lens 52 and the third imaging objective lens 54 consist of two groups of lenses successively distributed along the light path advancing direction. The third grating 53 is a volume holographic diffraction grating, and the spectral diffraction range of the third grating 53 is from 1040 nm to 1100 nm. The included angle between the light source incident direction of the third grating 53 and the end face of the third grating 53 facing the light source is between 45° and 65°. The third collimating objective lens 52 successively includes a third plano-concave lens 521 and a third plano-convex lens 522 along the light path advancing direction. The third imaging objective lens 54 successively includes a fourth plano-convex lens 541 and a fourth plano-concave lens 542 along the light path advancing direction. The type of the third grating 53 of the present invention is volume holographic diffraction and its optimal spectral diffraction is from 1040 nm to 1100 nm, ensuring that the light of the third channel 5 is fully dispersed, and the grating line density of the third grating 53 is the same as or different from that of the second grating 43.

[0028] The above-mentioned first linear array camera 35, second linear array camera 45, and third linear array camera 55 are all of the same model of linear array camera, avoiding the incompatibility between the camera and the computer 6 and the incompatibility in spectral information processing. The first grating 33, second grating 43, and third grating 53 are all volume holographic diffraction gratings, providing guarantee for clear and accurate spectral images.

[0029] Combined Figures 1 to 5 As shown, the system principle is as follows: The spectrum of the broadband light source 1 is divided into three paths by the beam splitter 2. The first channel 3 is connected to the first output end 201 of the beam splitter 2, where the light transmission band of the first channel 3 is from 350 nm to 880 nm. The second output end 202 of the beam splitter 2 is connected to the second channel 4, where the light transmission band of the second channel 4 is from 870 nm to 1050 nm. The third output end 203 of the beam splitter 2 is connected to the third channel 5, where the light transmission band of the third channel 5 is from 1040 nm to 1100 nm. The first channel 3, second channel 4, and third channel 5 are connected to the computer 6, decomposing the ultra-wide spectrum of the broadband light source 1 from 350 nm to 1100 nm into three dispersion channels, achieving high-precision detection of the ultra-wide spectrum from visible light to near-infrared. The first grating 33, second grating 43, and third grating 53 all adopt volume holographic diffraction gratings, which can effectively eliminate ghost lines and reduce the stray light level, providing ultra-high diffraction efficiency.

[0030] Although the embodiments of the present invention have been disclosed as above, they are not limited to only the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to specific details.

Claims

1. A multi-channel diffraction spectrum splitting system based on volume holographic diffraction grating, characterized in that: The multi-channel diffraction spectrum splitting system based on volume holographic diffraction grating comprises a wide-spectrum light source, a beam splitter connected to the wide-spectrum light source, at least one channel optical path respectively connected to the beam splitter, and a computer connected to the channel optical path, wherein the channel optical path is provided with a volume holographic diffraction grating as a dispersion element; The channel optical path includes a filter, a collimating objective lens, a grating, an imaging objective lens and a linear array camera in sequence along the optical path advancing direction; the filter is connected to the beam splitter, and the linear array camera is connected to the computer.

2. A multi-channel diffraction spectrum splitting system based on volume holographic diffraction grating as claimed in claim 1, characterized in that: The beam splitter is provided with an input end connected to the wide-spectrum light source and an output end connected to the channel light path, and the number of the output ends is the same as the number of the channel light paths.

3. The multi-channel diffraction spectrum splitting system based on volume holographic diffraction grating according to claim 1, characterized in that: The spectrum range of the broadband light source is from 350nm to 1100nm.

4. The multi-channel diffraction spectrum splitting system based on volume holographic diffraction grating according to claim 1, characterized in that: The multi-channel diffraction spectrum splitting system based on volume holographic diffraction grating is provided with three channel optical paths arranged in parallel between the beam splitter and the computer, including a first channel, a second channel and a third channel. The beam splitter is respectively provided with a first output end, a second output end and a third output end connected to the first channel, the second channel and the third channel. The first channel, the second channel and the third channel are respectively connected to the computer; the first channel, the second channel and the third channel are all provided with volume holographic diffraction gratings as dispersion elements.

5. A multi-channel diffraction spectrum splitting system based on volume holographic diffraction grating as claimed in claim 4, characterized in that: The first channel includes a first filter, a first collimating objective lens, a first grating, a first imaging objective lens and a first linear array camera in sequence along the direction of advance of the light path; the spectral range of the first channel is 350nm to 880nm, the filtering range of the first filter is 350nm to 880nm, the first collimating objective lens and the first imaging objective lens are both composed of four groups of lenses distributed in sequence along the direction of advance of the light path; the first grating is a volume holographic diffraction grating, and the spectral diffraction range of the first grating is 350nm to 880nm.

6. A multi-channel diffraction spectrum splitting system based on volume holographic diffraction grating as claimed in claim 5, characterized in that: The angle between the incident direction of the light source of the first grating and the end face of the first grating facing the light source is 75°-85°; The first collimating objective lens includes a first plano-convex lens, a first concave-convex lens, a second concave-convex lens, and a first convex lens in sequence along the advancing direction of the optical path; The first imaging objective lens includes a second convex lens, a third concave-convex lens, a fourth concave-convex lens, and a third convex lens in sequence along the direction of light path.

7. A multi-channel diffraction spectrum splitting system based on volume holographic diffraction grating as claimed in claim 4, characterized in that: The second channel includes a second filter, a second collimating objective lens, a second grating, a second imaging objective lens and a second linear array camera in sequence along the direction of the optical path. The spectral range of the second channel is 870nm to 1050nm. The filtering range of the second filter is 870nm to 1050nm. The second collimating objective lens is composed of two groups of lenses distributed in sequence along the direction of the optical path. The second imaging objective lens is composed of three groups of lenses distributed in sequence along the direction of the optical path. The second grating is a volume holographic diffraction grating, and the spectral diffraction range of the second grating is 870nm to 1050nm.

8. The multi-channel diffraction spectrum splitting system based on volume holographic diffraction grating according to claim 7, characterized in that: The angle between the incident direction of the light source of the second grating and the end face of the second grating facing the light source is 65°-80°; The second collimating objective lens includes a second plano-concave lens and a second plano-convex lens in sequence along the advancing direction of the optical path; The second imaging objective lens includes a fourth convex lens, a biconcave lens, and a fifth convex lens in sequence along the direction of the optical path.

9. The multi-channel diffraction spectrum splitting system based on volume holographic diffraction grating according to claim 4, characterized in that: The third channel includes a third filter, a third collimating objective lens, a third grating, a third imaging objective lens and a third linear array camera in sequence along the direction of advance of the optical path; the spectral range of the third channel is 1040nm to 1100nm; the filtering range of the third filter is 1040nm to 1100nm; the third collimating objective lens and the third imaging objective lens are both composed of two groups of lenses distributed in sequence along the direction of advance of the optical path; the third grating is a volume holographic diffraction grating; and the spectral diffraction range of the third grating is 1040nm to 1100nm.

10. The multi-channel diffraction spectrum splitting system based on volume holographic diffraction grating according to claim 9, characterized in that: The angle between the incident direction of the light source of the third grating and the end face of the third grating facing the light source is 45°-65°; The third collimating objective lens includes a third plano-concave lens and a third plano-convex lens in sequence along the advancing direction of the optical path; The third imaging objective lens includes a fourth plano-convex lens and a fourth plano-concave lens in sequence along the advancing direction of the optical path.

Images