CN115597711A - Spectrometer and light path design method thereof - Google Patents
Spectrometer and light path design method thereof Download PDFInfo
- Publication number
- CN115597711A CN115597711A CN202211616893.3A CN202211616893A CN115597711A CN 115597711 A CN115597711 A CN 115597711A CN 202211616893 A CN202211616893 A CN 202211616893A CN 115597711 A CN115597711 A CN 115597711A
- Authority
- CN
- China
- Prior art keywords
- light
- lens
- distortion
- splitting element
- prism
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims abstract description 29
- 238000013461 design Methods 0.000 title abstract description 14
- 239000006185 dispersion Substances 0.000 claims abstract description 61
- 230000003287 optical effect Effects 0.000 claims abstract description 47
- 230000003595 spectral effect Effects 0.000 claims abstract description 34
- 239000002131 composite material Substances 0.000 claims abstract description 9
- 230000005540 biological transmission Effects 0.000 claims abstract description 7
- 238000005452 bending Methods 0.000 claims description 106
- 239000000758 substrate Substances 0.000 claims description 9
- 238000011156 evaluation Methods 0.000 claims description 8
- 210000001747 pupil Anatomy 0.000 claims description 6
- 230000001419 dependent effect Effects 0.000 claims description 2
- 230000000149 penetrating effect Effects 0.000 claims description 2
- 210000000887 face Anatomy 0.000 claims 1
- 238000003384 imaging method Methods 0.000 abstract description 34
- 238000005259 measurement Methods 0.000 abstract description 28
- 230000004075 alteration Effects 0.000 abstract description 14
- 238000001514 detection method Methods 0.000 abstract description 10
- 238000001228 spectrum Methods 0.000 description 50
- 238000010586 diagram Methods 0.000 description 9
- 238000006073 displacement reaction Methods 0.000 description 9
- 238000012545 processing Methods 0.000 description 9
- 238000004611 spectroscopical analysis Methods 0.000 description 8
- 238000004422 calculation algorithm Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 238000005457 optimization Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000004458 analytical method Methods 0.000 description 3
- 238000012512 characterization method Methods 0.000 description 3
- 238000012938 design process Methods 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000012876 topography Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000012937 correction Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005286 illumination Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000011002 quantification Methods 0.000 description 2
- 206010010071 Coma Diseases 0.000 description 1
- 238000004026 adhesive bonding Methods 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 201000009310 astigmatism Diseases 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000007405 data analysis Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/02—Details
- G01J3/0205—Optical elements not provided otherwise, e.g. optical manifolds, diffusers, windows
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
- G01J3/28—Investigating the spectrum
Landscapes
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- General Physics & Mathematics (AREA)
- Spectrometry And Color Measurement (AREA)
Abstract
The application provides a spectrometer and a light path design method thereof, which relate to the technical field of optical detection and comprise a light source and a beam splitter prism arranged at the light emergent side of the light source, wherein a transmission light path of the beam splitter prism is provided with a dispersion objective lens, a light beam emitted by the light source is transmitted by the beam splitter prism and emits linear dispersion light through the dispersion objective lens, the linear dispersion light irradiates a detected object to form composite multi-wavelength reflected light, and the composite multi-wavelength reflected light penetrates through the dispersion objective lens and is reflected by the beam splitter prism; a curved slit device, a collimating mirror group, a light splitting element, a focusing mirror group and a camera are sequentially arranged on a reflection light path of the beam splitting prism, a plurality of light through holes are formed in the curved slit device, and the curved slit device protrudes towards one side of the beam splitting prism along the arrangement direction of the light through holes and is arc-shaped. The residual distortion aberration of the curved slit device and the light splitting element is well corrected, so that the curved slit device has smaller imaging spectral line curve, and the axial measurement precision is improved.
Description
Technical Field
The application relates to the technical field of optical detection, in particular to a spectrometer and a light path design method thereof.
Background
The surface appearance detection is usually carried out by adopting a line spectrum confocal system, the principle is that the distance is measured by utilizing wavelength information, a beam of linear wide-spectrum compound color emitted by a light source generates dispersion through a dispersion lens group, linear monochromatic light with different wavelengths is formed at a dispersion focal plane, and the focus of each wavelength corresponds to a distance value. The measuring light irradiates the surface of an object and is reflected back, only monochromatic light meeting confocal conditions can be sensed by a spectrometer through a small hole or a slit, and a distance value is obtained through conversion by calculating the wavelength of a detected focus.
The spectrum confocal measurement system belongs to the precision engineering range of precision manufacturing, ultra-precision manufacturing, fine processing and the like, and meanwhile, the light path composition of the spectrum confocal measurement system is complex, the processing and adjusting difficulty is high, the processing tolerance requirement is too high, the actual processing cannot meet or the adjusting method cannot control the tolerance, particularly, the residual distortion aberration is extremely large, and accordingly, the imaging spectrum is bent greatly. The imaging spectrum bending seriously affects the calibration of the relationship between the sensor pixel and the wavelength of the spectrum confocal measurement system, the calibration of the relationship between the wavelength and the displacement, the identification of a later algorithm image and the effective use area of a detector, so that the working waveband range of the dispersive objective lens is seriously reduced, namely the precision of axial measurement is reduced.
The imaging spectrometer for the spectral confocal measurement system in the prior art has the defects that the residual distortion aberration is very large, the imaging spectrum can not be corrected, the axial measurement precision of the spectral confocal measurement system is seriously influenced, and the collimating light path and the focusing light path can not deflect coaxially or at a small angle due to the overlarge deflection angle of the light path, so that the adjustment difficulty of the light path at the later stage is increased, and the residual distortion and other aberrations are increased due to the influence on the adjustment precision, so that the imaging spectrum is bent more.
Disclosure of Invention
The embodiment of the application aims to provide a spectrometer and a light path design method thereof, which can solve the problem that the imaging spectrum of the existing linear optical spectrum confocal system is seriously bent.
In one aspect of the embodiment of the application, a spectrometer is provided, which includes a light source and a beam splitter prism arranged on a light exit side of the light source, wherein a transmission light path of the beam splitter prism is provided with a dispersion objective lens, a light beam emitted from the light source is transmitted through the beam splitter prism and emits linear dispersion light through the dispersion objective lens, the linear dispersion light irradiates a measured object to form composite multi-wavelength reflected light, and the composite multi-wavelength reflected light penetrates through the dispersion objective lens and is reflected by the beam splitter prism; a curved slit device, a collimating mirror group, a light splitting element, a focusing mirror group and a camera are sequentially arranged on a reflection light path of the beam splitting prism, a plurality of light through holes are formed in the curved slit device, and the curved slit device protrudes towards one side of the beam splitting prism along the arrangement direction of the light through holes and is arc-shaped.
Optionally, the bending function y of the curved slit device and the distortion bending function y of the dispersive objective lens 2 Satisfy the relation: (100 | y-y) 2 ｜)/( ｜y 2 ｜)≤0.5%；
Distortion bending function y of light splitting element 1 Satisfies the following conditions: y is 1 =ax 3 +bx 2 +cx+d；
Distortion bending function y of dispersive objective lens 2 Satisfies the following conditions: y is 2 =a＇x 3 +b＇x 2 +c＇x+d＇；
Wherein x is the length of the light through hole, and a, b, c, d, a ', b', c ', d' are constants respectively.
Optionally, the focal length of the collimating lens group is equal to the focal length of the focusing lens group, and the collimating lens group and the focusing lens group are symmetrically arranged along the light splitting element.
Optionally, the light splitting element includes a first prism, a grating, and a second prism glued in sequence, and the first prism and the second prism are symmetrically disposed along the grating.
Optionally, a diaphragm is disposed on the light incident surface or the light emergent surface of the grating.
Optionally, a 0-level light trap is disposed on the light exit side of the light splitting element, and is configured to absorb 0-level dispersed light in the light beam emitted by the light splitting element.
Optionally, the 0-level optical trap is located below the 1-level dispersed light in the light beam emitted from the light splitting element, and has a gap with the focusing lens group.
Optionally, the focusing lens group comprises a first lens with positive focal power, a second lens with negative focal power, a third lens with positive focal power, a fourth lens with negative focal power, a fifth lens with negative focal power, a sixth lens with positive focal power, a seventh lens with positive focal power, an eighth lens with positive focal power, a ninth lens with positive focal power and a tenth lens with negative focal power;
the absolute value of the sum of the focal powers of the first lens and the second lens is less than or equal to 0.0058; the absolute value of the sum of the powers of the third lens and the fourth lens is less than or equal to 0.018; the absolute value of the sum of the focal powers of the fifth lens and the sixth lens is less than or equal to 0.0032; the absolute value of the sum of the focal powers of the seventh lens and the eighth lens is less than or equal to 0.0186; the absolute value of the sum of the optical powers of the ninth lens and the tenth lens is 0.0211 or less.
Optionally, the lens f-number of the focusing lens group is between 3.0 and 5.0, the telecentricity of the focusing lens group is less than 0.1 degrees, the focal length of the focusing lens group is between 60mm and 100mm, and the entrance pupil distance of the focusing lens group is more than 40mm.
Optionally, the curved slit apparatus includes a substrate, a plurality of light passing holes penetrating through the substrate; a high-reflection film is arranged on the substrate.
In another aspect of the embodiments of the present application, a method for designing an optical path of a spectrometer is provided, where the method is applied to the spectrometer, and includes: acquiring parameters of the light splitting element, and establishing a light splitting element model;
acquiring the parameters of an actual collimating lens group, acquiring the parameters of an actual focusing lens group, and obtaining the distortion bending function y of the light splitting element 1 ；
Establishing a dispersion objective lens model to obtain a distortion bending function y of the dispersion objective lens 2 ；
When (100 | y) 1 +y 2 ｜)/( ｜y 2 | is ≦ 0.5%, then y is determined 1 、y 2 As a function of the spectral line bending minimum of the spectrometer;
according to the bending function y of the bending slit device and the distortion bending function y of the dispersive objective lens 2 Satisfies (100 x | y-y) 2 ｜)/( ｜y 2 | is less than or equal to 0.5%, and the bending function y of the bending slit device is obtained 2 ；
When not satisfied (100 x | y) 1 +y 2 ｜)/( ｜y 2 | is less than or equal to 0.5%, the parameters of the light-splitting element, the parameters of the collimating lens group and the convergence are determined againThe parameters of the focal lens group, or the parameters of the dispersive objective lens are determined again.
Optionally, obtaining parameters of the spectroscopic element, and establishing the spectroscopic element model includes:
acquiring a transmission grating with the groove number of the grating in the range of 300lp/mm-600 lp/mm;
the method comprises the steps of obtaining a first prism of a light splitting element, wherein the inclination angle of the first prism is between 5 and 50 degrees, the refractive index of the first prism is between 1.0 and 1.8, the Abbe number of the first prism is between 17 and 90, and the thickness of the first prism is between 4 and 50 mm; wherein, the inclination angle is an included angle between the edge surface and the vertical surface; the setting parameters of the second prism of the light splitting element are the same as those of the first prism;
the light beam entering the light splitting element and the light beam emitted by the light splitting element are respectively 0 degree;
according to the requirements of 0 deg. incidence light-splitting element of light beam and 0 deg. emergence of light beam from light-splitting element and inclination angle beta of first prism 1 = angle of inclination of second prism beta 2 Obtaining dependent operands constrains the chief ray angle and makes beta 1 =β 2 And editing an evaluation function by taking the image quality and the distortion as evaluation indexes, optimizing and establishing an ideal light splitting element model and determining initial parameters of the light splitting element.
Optionally, obtaining parameters of an actual collimating lens group, obtaining parameters of an actual focusing lens group, and obtaining a distortion bending function y of the light splitting element 1 The method comprises the following steps:
acquiring a collimating lens group model and a focusing lens group model, enabling a light beam entering a light splitting element and a light beam emitted by the light splitting element to be 0 degrees respectively, and enabling the inclination angle of a first prism and the inclination angle of a second prism of the light splitting element to be equal;
when the image quality is optimal and the distortion value is minimal, the edge wavelength lambda is output 1 Edge wavelength lambda 2 And a central wavelength lambda 0 ；
From the edge wavelength lambda 1 Edge wavelength lambda 2 And a central wavelength lambda 0 Selecting a wavelength corresponding to the distortion value in the middle from the distortion data of the three wavelengths as a typical wavelength, and extracting the edge field distortion data of the grid distortion data corresponding to the typical wavelength;
performing polynomial fitting on coordinate data formed by the grid distortion data to obtain a distortion bending function y of the light splitting element 1 。
Optionally, a dispersive objective lens model is established to obtain a distortion bending function y of the dispersive objective lens 2 The method comprises the following steps:
making the parameters of the dispersive objective lens within a preset range;
when the image quality is optimal and the distortion value is minimal, the edge wavelength lambda is output 1 Edge wavelength lambda 2 And a central wavelength lambda 0 ；
From the edge wavelength lambda 1 Edge wavelength lambda 2 And a central wavelength lambda 0 Selecting a wavelength corresponding to a distortion value between the three wavelengths as a typical wavelength from the distortion data of the three wavelengths, and extracting edge field distortion data of grid distortion data corresponding to the typical wavelength;
performing polynomial fitting on coordinate data formed by the grid distortion data to obtain a distortion bending function y of the dispersive objective lens 2 。
According to the spectrometer and the light path design method thereof, the residual distortion aberration of the curved slit device and the light splitting element is well corrected, so that the curved slit device and the light splitting element have smaller imaging spectral line curvature, the calibration of the relationship between the sensor pixel and the wavelength and the calibration of the relationship between the wavelength and the displacement of a spectral confocal measurement system are very facilitated, and the recognition degree of a later-stage image algorithm is also improved; and the effective use area of the detector is increased due to smaller imaging spectral line bending, so that the working waveband range of the dispersion objective is enlarged, and the axial measurement precision is improved.
Drawings
To more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and that those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.
Fig. 1 is a schematic structural diagram of a spectrometer provided in this embodiment;
FIG. 2 is a schematic diagram of slit images with different wavelengths imaged on a target surface of a camera according to the present embodiment;
FIG. 3 is a schematic structural diagram of a curved slit device provided in this embodiment;
fig. 4 is a parameter schematic diagram of a PGP spectroscopic element provided in this embodiment;
FIG. 5 is an ideal model diagram of the PGP spectrometer provided in this embodiment;
FIG. 6 shows the ZEMAX edge wavelength λ provided by the present embodiment 1 A grid distortion map of (a);
FIG. 7 shows a ZEMAX center wavelength λ provided by the present embodiment 0 A grid distortion map of (a);
FIG. 8 shows the ZEMAX edge wavelength λ provided by the present embodiment 2 A grid distortion map of (a);
FIG. 9 is a characterization function y of the distortion curve at a typical wavelength of the PGP spectrum system provided in this embodiment 1 Drawing;
FIG. 10a is a schematic view of a collimator set and a focusing set of the present embodiment;
FIG. 10b is a second schematic view of the collimating lens assembly and the focusing lens assembly provided in this embodiment;
FIG. 11 is a grid distortion plot of typical wavelengths of the PGP spectroscopy system provided in this embodiment;
FIG. 12 is a distortion bending function y of typical wavelength of the PGP spectrum system provided by the present embodiment 1 Drawing;
FIG. 13 is an ideal spectrometer model diagram of the spectrometer based on grating spectroscopy only according to the present embodiment;
FIG. 14 is a graph of a line bending function of an ideal spectrometer based on grating spectroscopy only provided by the present embodiment;
FIG. 15 is a graph showing the bending function y of the typical wavelength distortion of the dispersive objective system provided in this embodiment 2 A drawing;
fig. 16 is a schematic diagram of a prior art imaging spectrometer for spectroscopic confocal measurements.
Icon: 10-a slit; 11-a collimating mirror; 12-a grating; 13-a focusing mirror; 14-a sensor; 101-a light source; 102-a beam splitting prism; 103-a dispersive objective lens; 104-curved slit apparatus;104 a-clear aperture; 104' -ideal slit means; 105-a collimating lens group; 105' -an ideal collimating lens group; 106-a light splitting element; 106 a-prism; 106 b-grating; 107-a focusing mirror group; 107' -an ideal focusing mirror group; 108-a camera; a 109-0 order light trap; a-ideal object plane; a' -an ideal image plane; l1-a first lens; l2-a second lens; l3-a third lens; l4-fourth lens; l5-a fifth lens; l6-sixth lens; l7-seventh lens; l8-eighth lens; l9-ninth lens; l10-tenth lens; beta is a 1 、β 2 -an inclination angle; n is a radical of an alkyl radical 1 、n 2 -a refractive index; d1, d 2-thickness; x-length; t-interval.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.
In the description of the present application, it should be noted that the terms "inside", "outside", and the like indicate orientations or positional relationships based on orientations or positional relationships shown in the drawings or orientations or positional relationships that the product of the application is usually placed in when used, and are used only for convenience of description and simplification of the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and operate, and thus, should not be construed as limiting the present application. Furthermore, the terms "first," "second," and the like are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.
It should also be noted that, unless expressly stated or limited otherwise, the terms "disposed" and "connected" are to be construed broadly, e.g., as meaning fixedly connected, detachably connected, or integrally connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in this application will be understood to be a specific case for those of ordinary skill in the art.
The surface topography detection is an important component of precision machining technology, and with the development of machining process level, the requirements on the range, precision and speed of the topography detection are higher and higher. The line spectrum confocal method is a detection method which is more advantageous in speed in the existing non-contact surface topography detection method. The line spectrum confocal measuring device is a measuring device for measuring the surface profile, displacement, three-dimensional appearance or thickness of an object by using broadband light dispersion and using an optical non-contact method. The measuring light irradiates the surface of an object and is reflected back, only monochromatic light meeting confocal conditions can be sensed by a spectrometer through a small hole or a slit, and a distance value is obtained through conversion by calculating the wavelength of a sensed focus.
The spectral confocal method is a non-contact micro-displacement measurement method based on wavelength displacement modulation, generally, calibration is needed to be carried out on the relationship between the sensor pixel and the wavelength of a spectral confocal measurement system after processing and assembling, and the relationship between the wavelength and the displacement, so the spectral confocal measurement system belongs to the precision engineering range of precision manufacturing, ultra-precision manufacturing, fine processing and the like, meanwhile, the composition of the optical path of the spectral confocal measurement system is relatively complex, the spectral confocal measurement system is mainly divided into a linear illumination module, a dispersion objective module and a spectrometer module, and all the modules are tightly matched; particularly, the illumination end is in a conjugate relationship with the dispersive focal plane of the dispersive objective lens, and is also in a conjugate relationship with the entrance slit, the entrance slit is subjected to dispersive imaging on the sensor, the requirement on coaxiality of an optical path is higher, meanwhile, the field of view of a linear optical spectrum confocal system is generally larger, the influence of off-axis aberration coma, astigmatism, field curvature and distortion is larger, the dispersive objective lens needs to be designed with a higher na (numerical aperture) in order to ensure higher transverse resolution, and a larger field of view is needed for higher scanning speed. The imaging spectrum is bent, the calibration of the relationship between the sensor pixel and the wavelength of the spectrum confocal measurement system is seriously influenced, the calibration of the relationship between the wavelength and the displacement and the identification of the algorithm image in the later period are seriously influenced, and the effective use area of a detector is reduced, so that the working waveband range of a dispersion objective lens is seriously reduced, and the precision of axial measurement is reduced.
The design of a typical line light spectrum confocal detection spectrometer refers to a spectrometer light path disclosed in the Chinese patent application publication (application number CN202110732241.5, publication number CN 113448050A), and the technical scheme of the prior art for an imaging spectrometer of a spectrum confocal measurement system mainly adopts an unbent slit and a collimating mirror to collimate light signals passing through the slit into parallel light beams, then the parallel light beams are split by a grating to form a dispersion spectrum, and a focusing mirror is arranged in the direction coaxial with a principal ray of a central wavelength of a +1 level or a-1 level of the spectrum and is used for focusing the spectrum signals of the +1 level or the-1 level of the spectrum on an imaging sensor to realize the imaging of the spectrum. As shown in fig. 16, including slit 10, collimating mirror 11, grating 12, focusing mirror 13 and sensor 14 that set gradually, this kind of technical scheme residual distortion aberration is often very big for this kind of structure, leads to the crooked unable correction of imaging spectrum, seriously influences the confocal measurement system's of spectrum axial measurement precision, and too big collimating optical path of light path deflection angle and the unable coaxial or the small-angle deflection of focusing optical path to increased the installation and adjustment degree of difficulty of later stage light path, the precision of influence installation and adjustment leads to the aberration increase such as residual distortion thereby to lead to bigger imaging spectrum to be crooked.
In view of this, the embodiments of the present application provide a spectrometer and a method for designing an optical path thereof, which can solve the problem of severe bending of an imaging spectrum of a linear optical spectrum confocal system, in order to solve the problem of severe bending of the imaging spectrum of the linear optical spectrum confocal system.
Specifically, referring to fig. 1, an embodiment of the present application provides a spectrometer, including: the light source 101 and the beam splitter prism 102 arranged on the light-emitting side of the light source 101, the dispersion objective 103 is arranged on the transmission light path of the beam splitter prism 102, the light beam emitted by the light source 101 is transmitted through the beam splitter prism 102 and emits linear dispersion light through the dispersion objective 103, the linear dispersion light irradiates a measured object to form composite multi-wavelength reflected light, and the composite multi-wavelength reflected light penetrates through the dispersion objective 103 and is reflected by the beam splitter prism 102;
a curved slit device 104, a collimating mirror group 105, a light splitting element 106, a focusing mirror group 107 and a camera 108 are sequentially arranged on a reflection light path of the beam splitting prism 102, a plurality of light through holes 104a are formed in the curved slit device 104, the arrangement of the light through holes 104a is in an arc shape, the curved direction of the arc is consistent with the distortion curved direction of the dispersion objective lens 103, and the curved slit device 104 protrudes towards one side of the beam splitting prism 102 along the arrangement direction of the light through holes 104a and is in an arc shape.
The light source 101 emits light beams towards the beam splitter prism 102, the light beams are transmitted by the beam splitter prism 102 and then emitted to the dispersion objective 103, so that the dispersion objective 103 emits linear dispersion light, the linear dispersion light generated by the dispersion objective 103 irradiates a measured object, the generated composite multi-wavelength reflected light is reflected by the dispersion objective 103 and the beam splitter prism 102 and focused at the curved slit device 104, focal planes of the linear dispersion light with different wavelengths correspond to different heights of the measured object, because the different focal planes and the light through hole 104a of the curved slit device 104 form a conjugate relation, monochromatic light meeting the conjugate relation can pass through the light through hole 104a of the curved slit device 104, monochromatic light not meeting the conjugate relation can be completely or partially blocked by the light through hole 104a of the curved slit device 104, all monochromatic light passing through the light through hole 104a is collimated into parallel light beams by the collimating mirror group 105, the beam splitter element 106 through which the parallel light beams pass, the beam splitter element 106 splits all incident monochromatic light of the parallel light and arranges the monochromatic light into spectra according to a certain sequence, and the focusing light spectrum 107 focuses the 1-level dispersion spectrum on the camera 108 to form slit image with different wavelengths.
As shown in fig. 2, due to different wavelengths of light (e.g., λ) 1 、λ 2 、λ 3 In particular, λ 1 Is shorter than lambda 2 And λ 2 Is shorter than lambda 3 Wavelength of) is dispersed and dispersed by the grating 106b, the outgoing angle is different, and thus the image focused on the target surface of the camera 108 with the resolution of 2560 × 1080 pixels is sequentially focused at a certain wavelength in the direction from 0 pixel to 1080 pixels of the short axis of the target surface of the camera 108Sequencing; if the light beams are arranged in the order from short wave to long wave, the slit images are the light beams corresponding to different wavelengths, which are filled in the curved slit device 104 and imaged on the target surface of the camera 108 by the spectrometer.
In the present application, as shown in fig. 3, the curved slit device 104 is arc-shaped, and n rectangular light passing holes 104a with a size of 5um × 5um are arranged in a linear distribution array with an equal interval t of 10 um; the curved slit device 104 includes a substrate through which a plurality of light passing holes 104a pass; a high-reflection film is arranged on the substrate. For example, the substrate material of the curved slit device 104 is a glass material with high transmittance in the visible light band, the rectangular light-passing regions with the size of the light-passing holes 104a being 5um × 5um are all plated with a high reflection film in the visible light band (400 nm to 700 nm), the size of the light-passing holes 104a is not limited to 5um × 5um and can be adjusted according to the signal intensity and resolution requirements, and the interval t of the light-passing holes 104a is not limited to 10um and can be adjusted according to the sampling rate of the line field of view, which is not limited to the above.
The light splitting element 106 is a PGP structure formed by gluing a prism 106a, a grating 106b and a prism 106a (the first prism and the second prism are symmetrical and can be regarded as the same prism 106 a), so that the deflection of a smaller optical path and smaller spectral bending are realized. The grating 106b includes a diffraction grating, a holographic grating, or a dispersion prism.
The bending of the curved slit device 104 can be comprehensively considered and determined by the distortion of the dispersive objective lens 103 and the distortion of the grating 106b, the line bending of the prism 106a and the field curvature distortion of the collimating mirror group 105 and the focusing mirror group 107, as well as the nonlinear dispersion of the light splitting element 106, wherein in consideration of the relationship that the slit (light through hole 104 a) and the dispersive surface of the dispersive objective lens 103 in the system are conjugate imaging, in order to allow effective optical signals satisfying the conjugate relationship to be detected by the sensor through the slit as much as possible, a large number of effective optical signals are prevented from being blocked by the incorrectly bent slit, thereby combining the distortion value of the dispersive objective lens 103, comprehensively considering the bending value of the curved slit device 104, and more accurately and more favorably measuring the signal-to-noise ratio of the system.
The different dispersion angles of different luminous points of the slit cause the spectral line of the imaging after the light is split by the prism 106a or the grating 106b to be bent, and the direction of the spectral line bending of the prism 106a and the direction of the spectral line bending of the grating 106b are opposite to each other according to the spectral line bending formula of the prism 106a and the spectral line bending formula of the grating 106b, so that the prism 106a and the grating 106b are combined to be used for compensating and correcting the spectral line bending in the design process according to the principle. Meanwhile, according to the rule of geometric imaging object image opposite sides, when the bending direction of the bending slit device 104 is opposite to the spectral line bending direction of the spectrometer system, mutual cancellation can be achieved, and therefore according to the principle, the spectrometer is designed based on the bending slit device 104 and the PGP (prism 106 a-grating 106 b-prism 106 a) light splitting element 106, and distortion of the dispersive objective lens 103 is considered, so that smaller spectral line bending is achieved.
According to the spectrometer provided by the embodiment of the application, the residual distortion aberration of the curved slit device 104 and the light splitting element 106 is well corrected, so that the curved slit device has smaller imaging spectral line curve, the calibration of the relationship between the sensor pixel and the wavelength of a spectral confocal measurement system and the calibration of the relationship between the wavelength and the displacement are very facilitated, and the identification degree of a later-stage image algorithm is improved; in particular, the effective use area of the detector is increased due to smaller imaging spectral line bending, so that the working waveband range of the dispersion objective 103 is increased, and the accuracy of axial measurement is improved.
Further, the bending direction of the curved slit device 104 is consistent with the bending direction of the grid distortion of the dispersive objective lens 103, and is opposite to the bending direction of the grid distortion of the system of the spectrometer (the spectrometer consisting of the ideal object plane a, the collimating lens group 105, the PGP beam splitting element 106, the focusing lens group 107 and the ideal image plane a'); particularly, considering that the distortion difference corresponding to the nonlinear dispersion wavelength is relatively large, the bending of the curved slit device 104 should comprehensively consider the middle value of the edge wavelength distortion and the center wavelength distortion in the wavelength band range, i.e. select the wavelength corresponding to the middle distortion value as the typical wavelength, mainly refer to the typical wavelength distortion value, so the bending function y of the curved slit device 104 and the distortion bending function y of the dispersive objective lens 103 2 Satisfy the relation: (100 | y-y) 2 ｜)/( ｜y 2 ｜)≤0.5%；
Distortion bending function y of the light splitting element 106 1 Satisfies the following conditions: y is 1 =ax 3 +bx 2 +cx+d；
Distortion bending function y of dispersive objective 103 2 Satisfies the following conditions: y is 2 =a＇x 3 +b＇x 2 +c＇x+d＇；
Where x is the length of the light-passing hole 104a, and a, b, c, d, a ', b', c ', d' are constants respectively.
When the above relationship is satisfied, the bending function y of the curved slit device 104 and the distortion bending function y of the typical wavelength of the PGP spectrum system 1 Cancel each other out to achieve a smaller line bend.
The focal length of the collimator group 105 is equal to that of the focusing group 107, and the collimator group 105 and the focusing group 107 are symmetrically disposed along the light splitting element 106.
When the focal length of the collimating mirror group 105 is equal to that of the focusing mirror group 107, the collimating mirror group 105 and the focusing mirror group 107 are the same lens, the lens is a single telecentric collimating or focusing lens, and the collimating mirror and the focusing mirror group 107 are combined into a double telecentric imaging system and are axially symmetrically distributed about the grating 106 b; similarly, the two prisms 106a are symmetrically arranged along the grating 106b, and the system diaphragm is placed on the surface of the grating 106b, specifically on the light incident surface or the light emitting surface of the grating 106b, and has a better effect when being positioned on the light emitting surface; therefore, the spectrometer of the present application has the significant characteristics of telecentric object space and image space, symmetric distribution, curved slit device 104, PGP beam splitting element 106, 0-level optical trap 109, and the like. The focal length f2 of the focusing lens group 107 or the focal length f1 of the collimating lens group 105 and the effective clear aperture phi 1 of the diaphragm satisfy: the ratio of f 1/phi 1 is more than or equal to 3 and less than or equal to 5, or the ratio of f 2/phi 1 is more than or equal to 3 and less than or equal to 5.
Further, a 0-order light trap 109 is provided on the light exit side of the spectroscopic element 106 for absorbing 0-order dispersed light in the light beam emitted through the spectroscopic element 106. The 0-level optical trap 109 collects all 0-level optical signals, so that the collection of effective spectrum information signals is prevented from being influenced, and the signal-to-noise ratio is favorably improved.
The 0-order light trap 109 is located below the 1-order dispersed light in the light beam emitted from the spectroscopic element 106 with a gap from the focusing mirror group 107. The 0-level optical trap 109 is placed below the light-emitting direction of the 1-level light by relying on the longer entrance pupil distance of the focusing lens group 107, does not interfere with the effective aperture of the 1-level light beam and the structure of the focusing lens group 107, is coaxial with the 0-level light optical axis as far as possible, has a large aperture, and collects all the 0-level light as far as possible.
As for the focusing lens group 107, in one embodiment of the present application, as shown in fig. 10a, the focusing lens group 107 includes a first lens L1 with positive power, a second lens L2 with negative power, a third lens L3 with positive power, a fourth lens L4 with negative power, a fifth lens L5 with negative power, a sixth lens L6 with positive power, a seventh lens L7 with positive power, an eighth lens L8 with positive power, a ninth lens L9 with positive power, and a tenth lens L10 with negative power;
the absolute value of the sum of the focal powers of the first lens L1 and the second lens L2 is less than or equal to 0.0058; the absolute value of the sum of the focal powers of the third lens L3 and the fourth lens L4 is less than or equal to 0.018; the absolute value of the sum of the focal powers of the fifth lens L5 and the sixth lens L6 is less than or equal to 0.0032; the absolute value of the sum of the powers of the seventh lens L7 and the eighth lens L8 is 0.0186 or less; the absolute value of the sum of the powers of the ninth lens L9 and the tenth lens L10 is 0.0211 or less. The level 0 optical trap 109 is set as shown in fig. 10 b.
Furthermore, the f-number of the lens of the focusing lens group 107 is between 3.0 and 5.0, the telecentricity of the focusing lens group 107 is less than 0.1 °, the focal length f of the focusing lens group 107 is between 60mm and 100mm, the entrance pupil distance of the focusing lens group 107 is more than 40mm, and the collimating lens group 105 and the focusing lens group 107 are the same lens.
Wherein, the f-number of the lens and the focal length f of the focusing lens group 107 satisfy: lens f-number = focal length f/diameter d of diaphragm; the telecentricity and the entrance pupil distance are independent parameters, the telecentricity enables the system to have smaller magnification error, and the longer entrance pupil distance enables the system to have a wider structural space.
On the other hand, the embodiment of the present application further discloses a method for designing an optical path of a spectrometer, which is applied to the spectrometer, and the method includes:
and S100, acquiring parameters of the light splitting element 106 and establishing a light splitting element 106 model.
Specifically, an ideal PGP spectrometer model is established in ZEAMX, and PGP parameters are preliminarily optimized.
Specifically, according to the resolution requirement of the line light spectrum confocal sensor system, the type of the grating 106b matched with the corresponding spectrum resolution is determined, and particularly, a transmission grating with the line number of the grating 106b in the range of 300lp/mm-600lp/mm is selected.
The prism 106a is initially configured with a configuration parameter set to a tilt angle β 1 Angle of inclination beta 2 Refractive index n 2 Abbe number vd, and thickness, as shown in the parameter diagram of prism 106a in FIG. 4, wherein the angle of inclination β 1 Angle of inclination beta 2 Are all arranged between 5 degrees and 50 degrees, and the refractive index n of the prism 106a 2 Is set between 1.0 and 1.8, n 1 Is the refractive index n of air 1 (ii) a The Abbe number vd is set between 17 and 90, and the thickness d1 and the thickness d2 of the prism 106a are both set between 4mm and 50 mm. Setting a parameter inclination angle beta of a prism 106a on ZEMAX optical simulation software 1 Angle of inclination beta 2 Refractive index n 2 Abbe number vd, and thickness, and each parameter satisfies the corresponding range requirement. Meanwhile, a PGP model is built on ZEMAX optical simulation software by initial parameters of the initial PGP light splitting element 106.
The beam splitting element 106 is incident and the beam is emitted at 0 DEG by the beam splitting element 106 according to the condition that the beam is incident at 0 DEG and the inclination angle beta of the first prism 1 = angle of inclination of second prism beta 2 Set up relevant operands on ZEMAX optical simulation software to constrain chief ray angle and make beta 1 =β 2 The image quality and distortion are used as evaluation indexes to edit an evaluation function, optimize and establish an ideal spectroscopic element 106 model and determine initial parameters of the spectroscopic element 106, as shown in fig. 5.
S110, acquiring the parameters of the actual collimating lens group 105 and the parameters of the actual focusing lens group 107 to obtain the distortion bending function y of the light splitting element 106 1 。
On the basis of an ideal PGP spectrometer model established by ZEMAX, an actually used collimating lens group 105 and a focusing lens group 107 are added to replace the ideal collimating lens group 105 'and the ideal focusing lens group 107' in the model, and then optimization design is carried out to obtain a bending function y of typical wavelength distortion of a PGP spectrum system 1 。
Specifically, on the basis of the above ideal PGP spectrometer model, models of the collimator lens group 105 and the focusing lens group 107 are sequentially introduced, and then relevant operands are set on the ZEMAX optical simulation software, the chief ray angle is constrained, and β is caused to be included 1 =β 2 Since the image quality and distortion are used as evaluation indexes, the refractive index n of the prism 106a is set 2 Thickness and angle of inclination beta 1 Angle of inclination beta 2 Parameters, such as curvature, thickness, air interval, materials and the like of the collimating mirror group 105 and the focusing mirror group 107 are used as variables, an evaluation function is edited, and all variable parameters are optimally designed;
when the optimization is carried out until the image quality is optimal and the distortion value is minimum, namely the bending is minimum (RMS wave aberration is taken as the standard for judging the image quality in the ZEMAX model so as to achieve the minimum RMS wave aberration value and the minimum distortion value, and the two values can be obtained by ZEMAX software), the ZEMAX edge wavelength lambda is output 1 Edge wavelength λ 2 And a central wavelength lambda 0 The grid distortion diagrams of (1) are shown in FIGS. 6 to 8, starting from the edge wavelength λ 1 Edge wavelength lambda 2 And a central wavelength lambda 0 In the distortion data of the three wavelengths, the wavelength corresponding to the distortion value in the middle is selected as the typical wavelength, and the typical wavelength is the center wavelength λ corresponding to the distortion middle value 0 A mesh distortion of 580nm as a distortion value of a typical wavelength;
considering the maximum distortion of the distortion characterization of the marginal field of view, extracting the distortion data of the marginal field of view, then carrying out polynomial fitting on coordinate data formed by the grid distortion data by using a data processing tool, and finally obtaining a distortion bending function y for characterizing the typical wavelength of the PGP (wavelength-generated Power Point) spectrum system 1 Characterization function of (a): y is 1 =ax 3 +bx 2 + cx + d (as shown in fig. 9).
S120, establishing a dispersion objective lens 103 model to obtain a distortion bending function y of the dispersion objective lens 103 2 。
Establishing a dispersive objective lens 103 model in ZEMAX, and then optimally designing to obtain a distortion bending function y of a typical wavelength of the dispersive objective lens 103 system 2 。
Similarly, the parameters of the dispersion objective 103 are set within a preset range;
when the image quality is optimal and the distortion value is minimal, the edge wavelength lambda is output 1 Edge wavelength lambda 2 And a central wavelength lambda 0 (ii) a The ZEMAX model takes RMS wave aberration as a standard for judging image quality so as to achieve the minimum RMS wave aberration value and the minimum distortion value, and the two values can be obtained by ZEMAX software. Edge wavelength lambda 1 Edge wavelength lambda 2 And a central wavelength lambda 0 Are respectively optimized by ZEMAX software, when the edge wavelength lambda is 1 When the conditions of optimal image quality and minimum distortion value are met, the corresponding edge wavelength lambda is output 1 The data of (a); when the edge wavelength lambda 2 When the conditions of optimal image quality and minimum distortion value are met, the corresponding edge wavelength lambda is output 2 The data of (a); when the center wavelength lambda 0 When the conditions of optimal image quality and minimum distortion value are satisfied, the corresponding central wavelength lambda is output 0 The data of (1).
From the edge wavelength lambda 1 Edge wavelength lambda 2 And a central wavelength lambda 0 Selecting the wavelength corresponding to the distortion value in the middle as a typical wavelength from the distortion data of the three wavelengths, and extracting the edge field distortion data of the grid distortion data corresponding to the typical wavelength;
performing polynomial fitting on the coordinate data to obtain a distortion bending function y of the dispersive objective lens 103 2 (ii) a The coordinate data is mesh distortion data corresponding to the wavelength, and as shown in fig. 6, 7, and 8, the mesh distortion data is actually composed of an X coordinate and a Y coordinate, where the X coordinate is a unit of a field of view mm, and the Y coordinate is a unit of an image height mm.
S130 | y (100 |) 1 +y 2 ｜)/( ｜y 2 | is ≦ 0.5%, then y is determined 1 、y 2 As a function of the minimum spectral line bending of the spectrometer.
Verifying the distortion bending function y of the typical wavelength of a dispersive objective 103 system 2 Distortion bending function y of typical wavelength of PGP spectral system 1 If (100 | y) 1 +y 2 ｜)/( ｜y 2 | is less than or equal to 0.5%, then y is determined 1 And y 2 Is the optimum combination, i.e. under this combinationThe line bending is minimal and therefore the bending function y ≈ y of the lower curved slit device 104 can be determined 2 。
Considering that the image of the slit is imaged on the camera 108, the bending function y of the curved slit device 104 and the distortion bending function y of the typical wavelength of the PGP spectrum system can be known from the rule of geometric optics imaging object image on different sides 1 When the sizes are equal and the directions are opposite, the functions of mutual cancellation can be achieved, so that distortion is reduced, spectral line bending is reduced, meanwhile, the focal lengths of the collimating lens group 105 and the focusing lens group 107 of the PGP spectrometer system are the same, and the diaphragm position is placed on the surface of the grating 106b, so that the PGP spectrometer system is a symmetrical imaging system, the magnification of the system is one time, and the bending function y of the curved slit device 104 and the distortion bending function y of the typical wavelength of the PGP spectrometer system are facilitated to be achieved 1 The effects of the mutual counteraction.
S140, according to the bending function y of the bending slit device 104 and the distortion bending function y of the dispersive objective lens 103 2 Satisfies (100 x | y-y) 2 ｜)/( ｜y 2 | is less than or equal to 0.5%, and the bending function y of the bending slit device 104 is obtained 2 。
Bending function y of the curved slit device 104 and the bending function y of the typical wavelength distortion of the dispersive objective 103 system 2 The conditions are required to be satisfied: (100 | y-y) 2 ｜)/( ｜y 2 | is less than or equal to 0.5%, i.e. y ≈ y 2 。
So that the bending function y of the curved slit device 104 and the bending function y of the typical wavelength distortion of the dispersive objective 103 system 2 The conditions are required to be satisfied: (100 | y-y) 2 ｜)/( ｜y 2 | is less than or equal to 0.5%, i.e. y ≈ y 2 . Considering that the slit and the focal plane corresponding to each monochromatic light on the dispersion surface of the dispersion objective 103 are in a conjugate relationship, the dispersion objective 103 is a linear field of view with the long side of the field of view being the same as the long side of the slit and the short side of the field of view being the same as the short side of the slit at the position corresponding to each monochromatic wavelength focal plane on the dispersion surface, the linear field of view and the slit in the dispersion direction of the dispersion objective 103 are in a conjugate imaging relationship, and (b) must be satisfied in order to allow effective optical signals satisfying the confocal condition to pass through the slit and be detected by the sensor as much as possible and to prevent a large amount of effective optical signals from being blocked by the slit in the incorrect bending direction100*｜y-y 2 ｜)/( ｜y 2 | is less than or equal to 0.5%, it is avoided as much as possible that a large number of effective optical signals are blocked at the edge of the light-transmitting hole 104a, which results in a decrease in the signal-to-noise ratio and causes uneven energy distribution at the edge and center of the spectral line, which affects the accuracy of the spectral confocal measurement.
S150. If not (100 | y) 1 +y 2 ｜)/( ｜y 2 | is less than or equal to 0.5%, the parameters of the beam splitting element 106, of the collimator set 105, of the focusing set 107, or of the dispersive objective 103 are re-determined.
Unsatisfied (100 | y) 1 +y 2 ｜)/( ｜y 2 | is less than or equal to 0.5%, returning to optimize the curvature, thickness, air spacing and material of the collimating and focusing lens assemblies 105 and 107, and the tilt angle β of the PGP beam splitting element 106 1 Angle of inclination beta 2 Refractive index n 2 Abbe number vd, thickness, etc. to meet the conditions, or to return to optimizing the curvature, thickness, air gap, material, etc. of the dispersive objective 103 to meet the conditions.
For example, the mesh distortion of the typical wavelength of the PGP spectroscopy system obtained by the above method is shown in fig. 11, and the edge data is further extracted and polynomial fitting is performed by using a data processing tool, so as to obtain the distortion bending function y of the typical wavelength of the PGP spectroscopy system 1 :y 1 =8*10 -16 x 3 -0.0003x 2 +0.0055x-6.4094; the system as shown in fig. 12 is designed to have a slit length x of 18mm, and the formula inputs x =18mm and x =9mm, respectively, and the slit edge height A1=6.4076mm and the slit center height A2=6.3842mm, respectively, and the line bend 23.4um can be obtained. The spectral line bending generated by the PGP spectrometer designed based on the design method is 23.4um, and the index of the spectral line bending is far better than that of a spectrometer based on light splitting of the grating 106 b.
Fig. 13 shows an ideal spectrometer model based on only grating 106b spectroscopy, including an ideal collimating mirror set 105 'and an ideal focusing mirror set 107', and fig. 14 shows a line bending function of an ideal spectrometer based on only grating spectroscopy, and substituting the same 18mm slit length x into the calculation, the line bending of the spectrometer based on only grating spectroscopy is about 81um.
Correspondingly designed bending function y of typical wavelength distortion of dispersive objective 103 system 2 As shown in FIG. 15, y 2 =-7*10 -16 x 3 +0.0003x 2 -0.0055x +6.4415. The system design slit length x is 18mm, and the formula inputs x =18mm and x =9mm respectively can obtain the edge height B1 ≈ 6.4397mm, the center height B2 ≈ 6.4163mm and the spectral line bending 23um.
Bending function y of typical wavelength distortion of verified dispersion objective 103 system 2 Need to satisfy (100 | y) 1 +y 2 ｜)/( ｜y 2 | is ≦ 0.5%, y in this case can be determined 1 And y 2 Is the optimum combination at which the spectral curve is minimal, considering y ≈ y 2 So the bending function y of the curved slit instrument 104 is ≈ y 2 ;
I.e. y ≈ -7 × 10 -16 x 3 +0.0003x 2 -0.0055x +6.4415, and satisfies (100 | y-y) 2 ｜)/( ｜y 2 | is less than or equal to 0.5%.
The curved slit instrument 104 may be curved by a curved function y ≈ -7 × 10 -16 x 3 +0.0003x 2 -0.0055x +6.4415 for custom processing.
It can be proven that the parameters of the PGP spectrometer, and the parameters of the curved slit device 104, are designed according to the above method steps to be very accurate and reliable; meanwhile, parameters are set by optical design software ZEMAX according to steps in the design process, optimization is carried out, analysis results of the ZEMAX are obtained finally, data results are very visual, quantification is achieved, and the steps are simple.
In summary, the present application provides the curved slit device 104 and the PGP splitting element 106, where the curvature of the curved slit device 104 is obtained by comprehensively considering the distortion of the dispersive objective lens 103, the distortion of the collimating lens group 105, the distortion of the focusing lens group 107, and the distortion of the PGP splitting element 106; the residual distortion aberration of the spectrometer system based on the curved slit device 104 and the PGP light splitting element 106 is well corrected, and particularly, the spectrometer system has smaller imaging line curvature, thereby being very beneficial to calibrating the relationship between the sensor pixel and the wavelength of a spectrum confocal measurement system and calibrating the relationship between the wavelength and the displacement, and improving the identification degree of a later-stage image algorithm; in particular, the smaller imaging line curvature increases the effective usable area of the detector, thereby increasing the operating band range of the dispersive objective 103, i.e. increasing the accuracy of the axial measurement.
In addition, a design method and steps of the spectrometer based on the curved slit device 104 and the PGP light splitting element 106 are optimized, parameters are set according to the steps in the design process by means of optical design software ZEMAX, then optimization is carried out, an analysis result of the ZEMAX is finally obtained, and a corrected imaging spectrum curvature value is finally obtained by combining data processing software; the method comprises the steps of decoupling optimization design, imaging spectrum bending analysis result imaging, imaging spectrum bending correction value quantification, and is simple and convenient to use and reliable in data analysis result by means of design of optical design software ZEMAX. Meanwhile, the spectrometer technology based on the curved slit device 104 and the PGP light splitting element 106 and the dispersion confocal technology are combined to design a spectrometer for line optical spectrum confocal detection, the spectrometer is used for a use scene of dispersion confocal, and meanwhile, the curved slit device 104 is obtained by comprehensively considering distortion of the dispersion objective lens 103, distortion of the collimator lens group 105, distortion of the focusing lens group 107 and distortion of the PGP light splitting element 106 together, under the application scene of the line optical spectrum confocal measurement system, the distortion influence of the dispersion objective lens 103 is considered, effective optical signals meeting a conjugate relation can be detected by a sensor through the curved slit device 104 more, so that a large number of effective optical signals are prevented from being blocked by an incorrectly curved slit, and therefore, the slit bending value comprehensively determined by combining the distortion of the dispersion objective lens 103, the distortion of the collimator lens group 105, the distortion of the focusing lens group 107 and the distortion of the PGP light splitting element 106 is more accurate, the signal to noise ratio is more beneficial to improvement, and the measurement accuracy of the line optical spectrum confocal measurement system is improved.
Furthermore, a 0-level light trap 109 is added, so that the influence of stray light on the identification of effective signals caused by the fact that 0-level light with stronger light energy irradiates the focusing mirror group 107 is avoided, and the signal-to-noise ratio of spectrum detection is improved.
The above description is only an example of the present application and is not intended to limit the scope of the present application, and various modifications and changes may be made to the present application by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (14)
1. A spectrometer, comprising: the light source and the beam splitter prism are arranged on the light emergent side of the light source, a dispersion objective lens is arranged on a transmission light path of the beam splitter prism, a light beam emitted by the light source is transmitted through the beam splitter prism and emits linear dispersion light through the dispersion objective lens, the linear dispersion light irradiates a measured object to form composite multi-wavelength reflected light, and the composite multi-wavelength reflected light penetrates through the dispersion objective lens and is reflected by the beam splitter prism;
the light splitting device is characterized in that a bending slit device, a collimating mirror group, a light splitting element, a focusing mirror group and a camera are sequentially arranged on a reflection light path of the light splitting prism, a plurality of light through holes are formed in the bending slit device, and the bending slit device faces one side of the light splitting prism in the arrangement direction of the light through holes and is in an arc shape.
2. The spectrometer of claim 1, wherein the bending function y of the curved slit device and the distortion bending function y of the dispersive objective lens 2 Satisfy the relation:
(100*｜y-y 2 ｜)/( ｜y 2 ｜)≤0.5%；
distortion bending function y of the light splitting element 1 Satisfies the following conditions: y is 1 =ax 3 +bx 2 +cx+d；
Distortion bending function y of the dispersive objective lens 2 Satisfies the following conditions: y is 2 =a＇x 3 +b＇x 2 +c＇x+d＇；
Wherein, x is the length of the light through hole, and a, b, c, d, a ', b', c ', d' are constants respectively.
3. The spectrometer of claim 1, wherein the focal length of the set of collimating lenses and the focal length of the set of focusing lenses are equal, and the set of collimating lenses and the set of focusing lenses are symmetrically disposed along the beam splitting element.
4. A spectrometer as claimed in any of claims 1 to 3 wherein the splitting element comprises a first prism, a grating and a second prism glued together in sequence, the first and second prisms being symmetrically arranged along the grating.
5. The spectrometer of claim 4, wherein a diaphragm is disposed on the light incident surface or the light emergent surface of the grating.
6. The spectrometer of any one of claims 1-3, wherein the light exit side of the light splitting element is provided with a 0 th order light trap for absorbing 0 th order dispersed light in the light beam exiting the light splitting element.
7. The spectrometer of claim 6, wherein the 0 th order light trap is positioned below the direction of the 1 st order dispersed light in the beam of light exiting the beam splitting element with a gap between the focusing mirror set.
8. The spectrometer according to any one of claims 1 to 3, wherein the focusing lens group comprises a first lens with positive optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with negative optical power, a fifth lens with negative optical power, a sixth lens with positive optical power, a seventh lens with positive optical power, an eighth lens with positive optical power, a ninth lens with positive optical power, and a tenth lens with negative optical power;
the absolute value of the sum of the focal powers of the first lens and the second lens is less than or equal to 0.0058; an absolute value of a sum of powers of the third lens and the fourth lens is 0.018 or less; the absolute value of the sum of the focal powers of the fifth lens and the sixth lens is less than or equal to 0.0032; the absolute value of the sum of the focal powers of the seventh lens and the eighth lens is less than or equal to 0.0186; an absolute value of a sum of powers of the ninth lens and the tenth lens is equal to or less than 0.0211.
9. The spectrometer of claim 8, wherein the f-number of the lens of the focusing lens group is between 3.0 and 5.0, the telecentricity of the focusing lens group is less than 0.1 °, the focal length of the focusing lens group is between 60mm and 100mm, and the entrance pupil distance of the focusing lens group is greater than 40mm.
10. The spectrometer of any of claims 1-3, wherein the curved slit apparatus comprises a substrate, a plurality of the light passing holes penetrating the substrate; the substrate is provided with a high-reflection film.
11. A method for designing an optical path of a spectrometer, applied to the spectrometer of any one of claims 1 to 10, comprising:
acquiring parameters of a light splitting element, and establishing a light splitting element model;
obtaining the actual parameters of the collimating lens group, obtaining the actual parameters of the focusing lens group, and obtaining the distortion bending function y of the light splitting element 1 ；
Establishing a dispersion objective lens model to obtain a distortion bending function y of the dispersion objective lens 2 ；
When (100 | y) 1 +y 2 ｜)/( ｜y 2 | is ≦ 0.5%, then y is determined 1 、y 2 As a function of the spectral line bending of the spectrometer being minimal;
according to the bending function y of the bending slit device and the distortion bending function y of the dispersive objective lens 2 Satisfies (100 x | y-y) 2 ｜)/( ｜y 2 | is less than or equal to 0.5%, and the bending function y of the bending slit device is obtained and is approximately equal to y 2 ；
When not satisfied (100 | y) 1 +y 2 ｜)/( ｜y 2 | is less than or equal to 0.5%, re-determining the parameters of the beam splitting element, the collimator set, the focusing set, or the dispersive objectParameters of the mirror.
12. The method of claim 11, wherein the obtaining parameters of the spectroscopic element and modeling the spectroscopic element comprises:
acquiring a transmission grating with the groove number of the grating in the range of 300lp/mm-600 lp/mm;
obtaining the first prism of the light splitting element, wherein the inclination angle is between 5 and 50 degrees, the refractive index is between 1.0 and 1.8, the Abbe number is between 17 and 90, and the thickness is between 4 and 50 mm; wherein the inclination angle is an included angle between the edge surface and the vertical surface; the setting parameters of the second prism of the light splitting element are the same as the setting parameters of the first prism;
the light beam entering the light splitting element and the light beam emitted by the light splitting element are respectively 0 degree;
according to the requirements of 0 deg. incidence of said light beam into said light-splitting element and 0 deg. emergence of said light beam from said light-splitting element and inclination angle beta of said first prism 1 = angle of inclination β of said second prism 2 Obtaining dependent operands constrains the chief ray angle and makes beta 1 =β 2 And editing an evaluation function by taking the image quality and the distortion as evaluation indexes, optimizing and establishing an ideal light splitting element model and determining initial parameters of the light splitting element.
13. The method as claimed in claim 11, wherein the obtaining of the parameters of the actual collimating lens set and the obtaining of the parameters of the actual focusing lens set are performed to obtain the distortion bending function y of the beam splitting element 1 The method comprises the following steps:
acquiring the collimating lens group model and the focusing lens group model, and enabling the light beam entering the light splitting element and the light beam emitted by the light splitting element to be 0 degrees respectively, so that the inclination angle of the first prism of the light splitting element is equal to that of the second prism;
when the image quality is optimal and the distortion value is minimal, the edge wavelength lambda is output 1 Edge wavelength lambda 2 And center waveLong lambda 0 ；
From the edge wavelength λ 1 The edge wavelength λ 2 And said central wavelength λ 0 Selecting a wavelength corresponding to a distortion value in the middle from the distortion data of the three wavelengths as a typical wavelength, and extracting edge field distortion data of grid distortion data corresponding to the typical wavelength;
performing polynomial fitting on coordinate data formed by the grid distortion data to obtain a distortion bending function y of the light splitting element 1 。
14. The method of claim 11, wherein the objective lens model is established to obtain a distortion bending function y of the objective lens 2 The method comprises the following steps:
making the parameters of the dispersive objective lens within a preset range;
when the image quality is optimal and the distortion value is minimal, the edge wavelength lambda is output 1 Edge wavelength lambda 2 And a central wavelength lambda 0 ；
From the edge wavelength λ 1 The edge wavelength λ 2 And said central wavelength λ 0 Selecting a wavelength corresponding to a distortion value in the middle from the distortion data of the three wavelengths as a typical wavelength, and extracting edge field distortion data of grid distortion data corresponding to the typical wavelength;
performing polynomial fitting on coordinate data formed by the grid distortion data to obtain a distortion bending function y of the dispersive objective lens 2 。
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211616893.3A CN115597711B (en) | 2022-12-16 | 2022-12-16 | Spectrometer and light path design method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211616893.3A CN115597711B (en) | 2022-12-16 | 2022-12-16 | Spectrometer and light path design method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN115597711A true CN115597711A (en) | 2023-01-13 |
| CN115597711B CN115597711B (en) | 2023-03-28 |
Family
ID=84854023
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202211616893.3A Active CN115597711B (en) | 2022-12-16 | 2022-12-16 | Spectrometer and light path design method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115597711B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115876447A (en) * | 2023-02-17 | 2023-03-31 | 聚时科技(深圳)有限公司 | Single-wavelength optical device detection device |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TW201205114A (en) * | 2010-07-23 | 2012-02-01 | Univ Nat Taipei Technology | Linear chromatic confocal microscope system |
| CN104034419A (en) * | 2014-05-05 | 2014-09-10 | 中国科学院长春光学精密机械与物理研究所 | Imaging spectrometer system capable of correcting bending of spectral line and correction method thereof |
| CN105190262A (en) * | 2013-02-19 | 2015-12-23 | 新加坡国立大学 | Diagnostic instrument and method |
| WO2018130693A1 (en) * | 2017-01-15 | 2018-07-19 | Baden-Württemberg Stiftung Ggmbh | Measurement system and method for combined capture of the surface topography and hyperspectral imaging |
| CN108709641A (en) * | 2018-06-19 | 2018-10-26 | 中国科学院上海技术物理研究所 | A kind of imaging spectrometer distortion compensation structure |
| CN111486953A (en) * | 2020-06-02 | 2020-08-04 | 南京引创光电科技有限公司 | Optical measuring system |
| CN112945382A (en) * | 2021-02-03 | 2021-06-11 | 中国科学院长春光学精密机械与物理研究所 | PGP imaging spectrometer for correcting spectral line bending and design method thereof |
| CN113447119A (en) * | 2021-06-29 | 2021-09-28 | 熵智科技(深圳)有限公司 | Line spectrum confocal sensor |
| CN115077697A (en) * | 2022-08-22 | 2022-09-20 | 无锡维度机器视觉产业技术研究院有限公司 | High-luminous-flux miniature optical fiber spectrometer |
-
2022
- 2022-12-16 CN CN202211616893.3A patent/CN115597711B/en active Active
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TW201205114A (en) * | 2010-07-23 | 2012-02-01 | Univ Nat Taipei Technology | Linear chromatic confocal microscope system |
| CN105190262A (en) * | 2013-02-19 | 2015-12-23 | 新加坡国立大学 | Diagnostic instrument and method |
| CN104034419A (en) * | 2014-05-05 | 2014-09-10 | 中国科学院长春光学精密机械与物理研究所 | Imaging spectrometer system capable of correcting bending of spectral line and correction method thereof |
| WO2018130693A1 (en) * | 2017-01-15 | 2018-07-19 | Baden-Württemberg Stiftung Ggmbh | Measurement system and method for combined capture of the surface topography and hyperspectral imaging |
| CN108709641A (en) * | 2018-06-19 | 2018-10-26 | 中国科学院上海技术物理研究所 | A kind of imaging spectrometer distortion compensation structure |
| CN111486953A (en) * | 2020-06-02 | 2020-08-04 | 南京引创光电科技有限公司 | Optical measuring system |
| CN112945382A (en) * | 2021-02-03 | 2021-06-11 | 中国科学院长春光学精密机械与物理研究所 | PGP imaging spectrometer for correcting spectral line bending and design method thereof |
| CN113447119A (en) * | 2021-06-29 | 2021-09-28 | 熵智科技(深圳)有限公司 | Line spectrum confocal sensor |
| CN115077697A (en) * | 2022-08-22 | 2022-09-20 | 无锡维度机器视觉产业技术研究院有限公司 | High-luminous-flux miniature optical fiber spectrometer |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115876447A (en) * | 2023-02-17 | 2023-03-31 | 聚时科技(深圳)有限公司 | Single-wavelength optical device detection device |
Also Published As
| Publication number | Publication date |
|---|---|
| CN115597711B (en) | 2023-03-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7315371B2 (en) | Multi-channel spectrum analyzer | |
| EP2051050B1 (en) | Spectrometer with cylindrical lens for astigmatism correction and demagnification | |
| US8212997B1 (en) | Chromatic confocal point sensor optical pen with extended measuring range | |
| US10234331B2 (en) | Monolithic spectrometer | |
| US20060114459A1 (en) | Optical fiber type spectroscope and spectroscope system equipped therewith | |
| JP2008256679A (en) | Chromatic confocal sensor | |
| CN111879239B (en) | Spectrum confocal measuring device and measuring method | |
| JP7410969B2 (en) | Spectral confocal measurement device and measurement method | |
| US20140347660A1 (en) | Metrological apparatus | |
| CN115597711B (en) | Spectrometer and light path design method thereof | |
| CN113447119B (en) | Line spectrum confocal sensor | |
| US20020024669A1 (en) | Spectral ellipsometer having a refractive illuminating optical system | |
| CN116202664B (en) | Wafer film stress detection system and method | |
| JP2016540243A (en) | Equipment for non-contact optical distance measurement | |
| CN115597499B (en) | Line light spectrum confocal measuring device | |
| JP2008032991A (en) | Reference lens for interferometer | |
| US7445390B2 (en) | Method and system for optically coupling components | |
| Krasilnikova et al. | Spatially resolved spectroscopy for non-uniform thin film coatings: comparison of two dedicated set-ups | |
| US10837832B2 (en) | Spectrometer and method for measuring the spectral characteristics thereof | |
| US20140233029A1 (en) | Spectrometer | |
| CN113448050B (en) | Spectrometer light path structure | |
| CN215375902U (en) | Spectrum appearance | |
| CN110567379A (en) | Spectrum confocal displacement sensor based on chirped fiber bragg grating | |
| WO2023185199A1 (en) | Spectral confocal measurement device | |
| WO2022149290A1 (en) | Displacement sensor |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| TR01 | Transfer of patent right | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20231110 Address after: Room 801, No. 1126 Shenbin South Road, Minhang District, Shanghai, 201107 Patentee after: MATRIXTIME ROBOTICS (SHANGHAI) Co.,Ltd. Address before: 518000 No. 4, Floor 4, Huashen Building, 1038 Aiguo Road, Xinyi Community, Huangbei Street, Luohu District, Shenzhen, Guangdong Province Patentee before: Jushi Technology (Shenzhen) Co.,Ltd. |