CN105333952B

CN105333952B - A kind of spectral measurement CCD module improving detectivity

Info

Publication number: CN105333952B
Application number: CN201510761783.XA
Authority: CN
Inventors: 黄梅珍; 余镇岗; 宋彪; 邹烨; 汪洋; 黄锦荣; 王柯卉
Original assignee: Shanghai Dynamo-Electric Co Ltd Of Speed Enlightening; Shanghai Jiao Tong University
Current assignee: Shanghai Dynamo-Electric Co Ltd Of Speed Enlightening; Shanghai Jiao Tong University
Priority date: 2015-11-10
Filing date: 2015-11-10
Publication date: 2019-05-31
Anticipated expiration: 2035-11-10
Also published as: CN105333952A

Abstract

The invention provides a spectral measurement CCD module with improved detection sensitivity, comprising an optical calibration unit with aberration correction and energy convergence functions, the optical calibration unit is arranged before the CCD; the optical calibration unit is a conventional cylindrical mirror or The unconventional cylindrical mirror is used to adjust both the converging position along the spectral height direction which affects the sensitivity and the focusing position along the spectral width direction which affects the resolution to the position where the CCD pixel is located; the unconventional cylindrical lens The mirror is a gradient-thickness cylindrical mirror with a constant curvature and a gradual thickness, or a gradient-curvature cylindrical mirror with a constant thickness and a gradual curvature, or a double-cemented cylindrical mirror. The invention integrates an optical correction unit with the functions of correcting aberration and condensing energy, and significantly improves the sensitivity and resolution of the detection spectrum. Further, the temperature is stably controlled by the refrigeration unit to reduce noise and signal drift.

Description

A kind of spectral measurement CCD module improving detectivity

Technical field

The present invention relates to optical detections, analysis field, and in particular, to a kind of spectral measurement for improving detectivity CCD module.

Background technique

CCD, full name in English: Charge-coupled Device, Chinese name: charge coupled cell is properly termed as CCD Imaging sensor is also image controller.It functionally divides, including line array CCD and area array CCD two major classes.

Sensitivity, resolution ratio, signal-to-noise ratio and baseline stability etc. are the important technology performance indicators of spectral instrument, with CCD especially line array CCD is in the spectral measurement device or instrument of receiver, due to CCD pixel limited height, light spectrum image-forming face Upper substantial portion of light energy can not be received by CCD photosurface, to constrain spectrometer to the detection energy of low light signals Power, i.e. sensitivity is not high.

On the other hand, the operating temperature of CCD directly affects the stability of signal noise and baseline, and temperature is lower, and noise is got over Small, the size of output signal varies with temperature significantly, therefore, in the application of high-precision spectral measurement, it is necessary to make to CCD Cold and thermostatic control, so that spectral signal keeps stablizing.

Summary of the invention

For the defects in the prior art, the object of the present invention is to provide a kind of spectral measurements for improving detectivity CCD module significantly improves the sensitivity of detecting light spectrum using the optical correction unit with aberration correction and convergence energy function And resolution ratio.

In order to achieve the above object, the present invention provides a kind of spectral measurement CCD module for improving detectivity, including have Optical correction's unit of aberration correction and energy convergence function, optical correction's unit are arranged before CCD；

Optical correction's unit is conventional cylindrical mirror or unconventional cylindrical mirror, for will affect sensitivity along spectrum The converged position of short transverse and the focal position along spectral width direction for influencing resolution ratio are adjusted to where CCD pixel Position on；

The unconventional cylindrical mirror is the progressive thickness cylindrical mirror or thickness not variable curvature of the constant gradient thickness of curvature The gradual curvature cylindrical mirror of gradual change or double glued cylindrical mirrors.

Preferably, the gradual curvature cylindrical mirror, design method are as follows: according to spectrometer without this gradual curvature cylindrical mirror The focal position of the focusing of lower optical path is distributed, and finds out the distribution coordinate of its each wavelength focus point, spectral condenser is spheric reflection Mirror, directional light incidence rear focal point are located at apart from spherical reflector r=1/2R_BallAt cos α, wherein R_BallIt is the half of spherical reflector Diameter, α are the angles at parallel input light and concave mirror center between normal, can be approximately considered focus distribution on circular arc, Angle locating for different wave length is different, obtains the relation curve of wavelength Yu focal length position；

Taking cylindrical mirror is plano-convex lens, parallel with plano-convex lens plane positioned at one to reach each wavelength focus location track For the purpose of rectification effect, design the curvature of lens at each position, complete the cylindrical lens design of curvature gradual change, plano-convex lens are burnt Away from formula are as follows: f_λ=r_λ/ (n-1), f_λIt is related with focal position distribution, it is obtained by fitting, according to fitting result, designs column The distribution of face mirror radius r.

Preferably, described device further comprises: playing the heat dissipation box of sealing and heat spreading function, the upper end of the heat dissipation box has Optical transmission window, optical correction's unit are set to the optical transmission window, and surrounding is filled with heat-insulating material in the heat dissipation box.

It is highly preferred that the bottom of the heat dissipation box at pectination piece type structure to increase surface area, in favor of heat dissipation, heat dissipation box Interior center is sequentially placed semiconductor chilling plate, heat-conducting block, temperature sensor and CCD by bottom upwards, and the temperature sensor buries Enter inside heat-conducting block；There are outlet hole, the wiring of the semiconductor chilling plate, temperature sensor and CCD in the side of the heat dissipation box Drawn from the outlet hole.

It is highly preferred that the material selection aluminium alloy or copper of the heat dissipation box.

It is highly preferred that each contact surface passes through and leads between the semiconductor chilling plate, heat-conducting block, temperature sensor and CCD Hot silica gel intimate contact.

It is highly preferred that the material selection red copper or aluminium alloy of the heat-conducting block.

It is highly preferred that the temperature sensor selects thermistor.

In the present invention, on the one hand, according to spectral instrument principle, complex light enters monochromator through slit, is collimated by collimating mirror Become directional light, then by grating or prism dispersion, light is assembled by focus lamp after dispersion, and different wavelengths of light is ultimately imaged On the different pixel positions of CCD, since slit has certain altitude plus optical system there are aberration, corresponding band has Certain height, since pixel height is limited, can only often receive a portion light when receiving signal using line array CCD As a result spectrum energy causes the detectivity of spectrometer low, be unable to measure weaker spectral signal.Using general condenser Although detectivity can be improved in method, but spectral resolution will decline at the same time.The present invention, which uses, has aberration correction It can solve this with optical correction's unit (conventional cylindrical mirror or unconventional cylindrical mirror) of energy convergence function to ask Topic.

On the other hand, the refrigeration control temperature unit that the present invention further uses CCD and heat dissipation box to constitute, realizes stability contorting temperature Degree significantly improves the sensitivity and resolution ratio of detecting light spectrum to reduce noise and signal drift.

Compared with prior art, the present invention have it is following the utility model has the advantages that

The present invention can effectively improve the detectivity of spectrometer using optical correction's unit, while keep higher light Spectral resolution；

In the present invention, the heat dissipation box with heat spreading function, the semiconductor system being sequentially placed upwards in box by bottom are sealed by Cold, heat-conducting block, temperature sensor and CCD, and be fixed on optical correction's unit composition of heat dissipation box upper end optical transmission window It is compact to close CCD refrigeration structure, does not need vacuumize process, is just able to satisfy the uniform refrigeration demand of CCD, which can be effective Completely cut off moisture, not only can be reduced CCD and extraneous heat exchange, but also CCD can be reduced because of the surface CCD fogging, frosting caused by humidity Influence.

The present invention proposes a kind of by CCD and refrigeration control temperature unit, the optics school with aberration correction and energy convergence function The multi-functional CCD modularity and modular structure that positive unit combines, not only can enhanced spectrum detectivity, It is able to maintain higher spectral resolution again.

Detailed description of the invention

Upon reading the detailed description of non-limiting embodiments with reference to the following drawings, other feature of the invention, Objects and advantages will become more apparent upon:

Fig. 1 is one embodiment of the invention structural schematic diagram；

In figure: heat dissipation box 1, semiconductor chilling plate 2, heat-conducting block 3, temperature sensor 4, CCD 5, heat-insulating material 6, outlet hole 7, optical correction's unit 8；

Fig. 2 is one embodiment of the invention spectrum line in meridian and sagittal surface focal imaging figure；

Fig. 3 is one embodiment of the invention spectrum line in meridian and sagittal surface imaging position curve graph；

Fig. 4 is that one embodiment of the invention meridional focus and sagittal focus distance Curve and its primary and secondary matched curve are shown It is intended to；

Fig. 5 (a) is the r of one embodiment of the invention variable curvature cylindrical mirror_λCurve synoptic diagram；

Fig. 5 (b) is one embodiment of the invention variable curvature cylindrical mirror schematic diagram.

Specific embodiment

The present invention is described in detail combined with specific embodiments below.Following embodiment will be helpful to the technology of this field Personnel further understand the present invention, but the invention is not limited in any way.It should be pointed out that the ordinary skill of this field For personnel, without departing from the inventive concept of the premise, various modifications and improvements can be made.These belong to the present invention Protection scope.

As shown in Figure 1, being a preferred embodiment of the invention, specifically, a kind of spectrum for improving detectivity is surveyed Measure CCD module, comprising: rise and seal and the heat dissipation box 1 of heat spreading function and heat-insulating material 6 and optical correction's unit 8, in which: institute There is optical transmission window in the upper end for stating heat dissipation box 1, and optical correction's unit 8 is set to the optical transmission window, and surrounding is filled in the heat dissipation box 8 There is heat-insulating material 6.

Optical correction's unit 8 is conventional cylindrical mirror or unconventional cylindrical mirror, for will affect sensitivity along light The converged position for composing short transverse and the focal position along spectral width direction for influencing resolution ratio are adjusted to CCD pixel institute Position on；The unconventional cylindrical mirror be the constant gradient thickness of curvature progressive thickness cylindrical mirror or thickness it is constant The gradual curvature cylindrical mirror of curvature gradual change or double glued cylindrical mirrors.

As a preferred embodiment, the bottom of heat dissipation box 1 at pectination piece type structure to increase surface area, in favor of dissipate Heat；Semiconductor chilling plate 2, heat-conducting block 3, temperature sensor 4 and the CCD5 that center is sequentially placed upwards by bottom in heat dissipation box 1, Each face passes through heat conductive silica gel intimate contact；Preferably, the temperature sensor 4 is embedded to inside heat-conducting block 3；The heat dissipation box 1 Side be provided with outlet hole 7, the wiring of the semiconductor chilling plate 2, temperature sensor 4 and CCD 5 is drawn from outlet hole 7； The upper end of the heat dissipation box 1 is provided with optical transmission window, and optical correction's unit 8 is fixed on the optical transmission window.

The present invention combines CCD with refrigeration control temperature unit, is able to achieve stability contorting temperature；Close CCD refrigeration structure It is compact, vacuumize process is not needed, the uniform refrigeration demand of CCD is just able to satisfy, which can effectively completely cut off moisture, can subtract Few CCD and extraneous heat exchange, and CCD can be reduced because of the surface CCD fogging caused by humidity, the influence of frosting.

In general, the aberration schematic diagram of meridian focus point and the sagittal focusing point of spectrum line imaging is as shown in Fig. 2, left in figure One side of something is the effect that meridian plane focuses, and the right is the effect that sagittal surface focuses, and meridian focuses on location A, generally a camber line, Sagittal surface is similar, focuses on B location.Since meridian focal plane and sagitta of arc focal plane separate, in addition the original of the limited height of ccd detector Cause, ccd detector can only receive very limited a part of light energy, cause spectral sensitivity low, resolution ratio is also low.

As a preferred embodiment, in order to improve the detectivity of spectrometer, and ensure spectrum high as far as possible point Resolution, optical correction's unit of the present invention can use cylindrical mirror or unconventional cylindrical mirror.The unconventional cylindrical mirror is curvature The progressive thickness cylindrical mirror thickness of the constant gradient thickness not gradual curvature cylindrical mirror of variable curvature gradual change or double Glued cylindrical mirror, it is therefore an objective to will affect the converged position along spectrum short transverse of sensitivity and influence resolution ratio along light The focal position in spectral width direction is adjusted on the position where CCD pixel.Specifically:

Scheme one places a convergence cylindrical mirror before CCD, and the spectral energy being distributed along short transverse more can Gather on CCD pixel, since the CCD receptor surface of spectrometer is usually linear array or face battle array, therefore son can be fitted with once linear Noon focal position is fitted to obtain spectral region resolution ratio totally preferable position by meridian focal position by once linear, according to This determines the angles and positions that CCD is put, and the placement angle of CCD is the angle that fitting a straight line slope provides, the position that CCD is put For fitting a straight line position.

It is focused and sagittal focusing position by optical simulation software it can be concluded that not increasing meridian when assembling cylindrical mirror before CCD Range difference curved line relation is set, as shown in Figure 3.The positional distance difference is compensated by the cylindrical mirror being added, and sagittal focusing position is adjusted To meridian focal position.Since the CCD receptor surface of spectrometer is usually linear array or face battle array, therefore can be fitted with once linear Meridian focal position, as shown in figure 4, by meridian focal position by once linear be fitted to obtain spectral region resolution ratio it is overall compared with Good position.

Scheme two, when having higher require to resolution ratio, the light of different wave length refractive index in same Propagation It is different, so the focus focused after cylindrical mirror is in approximately the same plane, and unconventional special optical is used to calibrate mirror Piece (unconventional cylindrical mirror), is able to achieve optically focused to increase sensitivity, while keeping good spectral resolution.

For example, the basic ideas for enhancing sensitivity in full spectral limit using variable curvature cylindrical mirror are will to focus on sagittal surface The upper light distribution for influencing longitudinal sensitivity adjusts to come on the focal position for gathering meridian plane with cylindrical mirror as far as possible, reduces to dividing It is influenced caused by resolution.

In one embodiment, the gradual curvature cylindrical mirror of thickness proposed by the present invention not variable curvature gradual change, design method with Process is as follows:

It is distributed according to the focal position of spectrometer focusing of optical path under without this optical correction's eyeglass, it is poly- to find out its each wavelength The distribution coordinate of focus, generally, spectral condenser are spherical reflector, and directional light incidence rear focal point is located at anti-apart from spherical surface Penetrate mirror r=1/2R_BallAt cos α, wherein R_BallFor the radius of spherical reflector, α is at parallel input light and concave mirror center Angle between normal can be approximately considered focus distribution on circular arc, and angle locating for different wave length is different, obtains wavelength and coke The relation curve of point distance and position.

For citing it is easy for the sake of, taking cylindrical mirror is plano-convex lens, with reach each wavelength focus location track positioned at one with Rectification effect for the purpose of plano-convex lens plane is parallel designs the curvature of lens at each position, and the column for completing curvature gradual change is saturating Mirror design.Plano-convex lens focal length formula are as follows: f_λ=r_λ/ (n-1), f_λIt is related with focal position distribution, it can be fitted and obtain, according to Fitting result designs the distribution of cylindrical mirror radius r.

Specifically, the design process of variable curvature cylindrical mirror radius r is as follows:

Assuming that a face of cylindrical mirror is plane, i.e. r=∞, by CCD apart from cylindrical mirror position L_InIt is required that spectrum line uses The central wavelength of spectral region can ignore the influence of thickness change focusing, by soft according to thin lens condition design in this way Part board design goes out the curvature r of cylindrical mirror at this time_InAnd thickness d_InAnd f_In.

The radius r of variable curvature cylindrical mirror is designed by the curve of conic fitting in Fig. 4 again.Specifically, by Fig. 4 two The meridian sagitta of arc focal position difference Δ Y of secondary curve matching² _λCurve when putting due to the cylindrical mirror, there is the tilt angle requirement of β, It is therefore desirable to by alternate position spike Δ Y at this time² _λIt is coordinately transformed, the Δ Y under conic fitting is rotated clockwise according to β² _λ Curve changes into Δ Y² _λ' relation curve, then there is the focal length expression of each wavelength of full spectral limit:

f_λ=f_In-(ΔY² _λ’-ΔY² _In)≈f_In-ΔY² _λ’+ΔY² _In；

By focal distance of thin convex lens formula: f_λ=r_λ/ (n-1) can calculate the curvature value at each wavelength X position, r_λAs become The radius value of curvature lens.

The r of variable curvature design lens in the present embodiment_λShown in curve such as Fig. 5 (a), the lens schematic diagram such as 5 (b) obtained It is shown.

Further, the present invention by CCD and refrigeration control temperature unit, the optics school with aberration correction and energy convergence function Positive unit organically combines, in addition to energy stability contorting temperature, moreover it is possible to which enhanced spectrum detectivity keeps higher spectrally resolved Rate.

Specific embodiments of the present invention are described above.It is to be appreciated that the invention is not limited to above-mentioned Particular implementation, those skilled in the art can make various deformations or amendments within the scope of the claims, this not shadow Ring substantive content of the invention.

Claims

1. a spectral measurement CCD module improving detection sensitivity, is characterized in that, comprises the optical calibration unit with aberration correction and energy convergence function, and described optical calibration unit is arranged before CCD;

The optical calibration unit is an unconventional cylindrical mirror, which is used to adjust both the converging position along the spectral height direction that affects the sensitivity and the focusing position along the spectral width direction that affects the resolution to the position where the CCD pixel is located;

The spectral measurement CCD module further comprises: a heat dissipation box for sealing and heat dissipation, the upper end of the heat dissipation box is provided with a light-transmitting window, the optical calibration unit is arranged in the light-transmitting window, and the heat-dissipating box is filled with heat insulating material around it; The bottom of the heat dissipation box is formed into a comb-shaped sheet structure to increase the surface area and facilitate heat dissipation. The center of the heat dissipation box is placed in order from the bottom to the top. Inside; the side of the heat dissipation box has a wire outlet hole, and the wiring of the semiconductor refrigeration chip, the temperature sensor and the CCD are all drawn out from the wire outlet hole;

The unconventional cylindrical mirror is a gradient curvature cylindrical mirror with a constant thickness and a gradual curvature;

The design method of the gradient curvature cylindrical mirror is as follows:

According to the focus position distribution of the optical path of the spectrometer without the gradient curvature cylindrical mirror, the distribution coordinates of the focus point of each wavelength are obtained. The spectral condenser is a spherical reflector, and the focus point is located at a distance from the spherical reflector after the parallel light is incident r= 1/2R _sphere cosα, where R _sphere is the radius of the spherical mirror, α is the angle between the incident light and the normal at the center of the concave mirror, and the angles at different wavelengths are different, and the wavelength and focal distance are obtained. position relationship curve;

Taking the cylindrical lens as a plano-convex lens, in order to achieve the correcting effect that the locus of each wavelength focusing position is located in a parallel with the plane of the plano-convex lens, the curvature of the lens at each position is designed, and the cylindrical lens design with curvature gradient is completed. The formula for the focal length of the plano-convex lens is: f _λ =r _λ /(n-1), f _λ is related to the focus position distribution, obtained by fitting, and according to the fitting result, the distribution of the radius r of the cylindrical lens is designed;

For the gradient curvature cylindrical mirror, the radius r is designed as follows:

Assuming that one surface of the cylindrical mirror is a plane, that is, r = ∞, it is required by the CCD distance from the cylindrical mirror position L _, the spectral line adopts the center wavelength of the spectral range, and is designed according to the thin lens condition, so that the influence of the thickness change on the focal length can be ignored. , the curvature r _{, the} thickness d _{and the} focal length f _of the cylindrical lens at this time are designed through software simulation;

Then use the curve fitted by the quadratic curve to design the radius r of the variable curvature cylindrical mirror. The meridional sagittal focus position difference △Y ² _λ curve fitted by the quadratic curve is used. When the cylindrical mirror is placed, there is a β According to the requirements of the tilt angle, the position difference △Y ² _λ at this time needs to be transformed into coordinates, and the △Y ² _λ curve fitted by the quadratic curve is rotated clockwise according to β, and converted into a △Y ² _λ ' relationship curve, then there is a full range of The focal length f _λ expression for each wavelength in the spectral range:

f _λ = f- ₍ △Y ² _λ '-△Y ² ₎ _≈f- △Y ² _λ '+△Y ² _;

From the thin lens focal length formula: f _λ =r _λ /(n-1), calculate the curvature radius value at each wavelength λ position, r _λ is the radius value of the variable curvature lens, and △Y ² _is the spectral line using the spectrum The meridional sagittal focus difference at the center wavelength of the range.

2 . The spectral measurement CCD module with improved detection sensitivity according to claim 1 , wherein the material of the heat dissipation box is selected from aluminum alloy or copper. 3 .

3 . The spectral measurement CCD module for improving detection sensitivity according to claim 1 , wherein each contact surface between the semiconductor refrigeration sheet, the heat-conducting block, the temperature sensor and the CCD is intimately contacted by thermally conductive silica gel. 4 .

4 . The spectral measurement CCD module with improved detection sensitivity according to claim 1 , wherein the material of the heat conducting block is selected from red copper or aluminum alloy. 5 .

5 . The spectral measurement CCD module for improving detection sensitivity according to claim 1 , wherein the temperature sensor is a thermistor. 6 .