CN2438107Y

CN2438107Y - Multiple grating monochromator by planar array CCD detector

Info

Publication number: CN2438107Y
Application number: CN 00209213
Authority: CN
Inventors: 张亿达
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-04-11
Filing date: 2000-04-11
Publication date: 2001-07-04
Anticipated expiration: 2010-04-11

Abstract

The utility model relates to a multiple grating monochromator which uses a planar array CCD detector and which belongs to the field of optical electronic devices. A new grating plane which is parallelly combined by a plurality of gratings covers the entire spectral region of a whole wavelength range of the CCD detector. The utility model can achieve high accuracy and fast scan of wavelength in the wavelength range from 200 to 1100 nm without any mechanical drive and gearshift. The principle of the multiple grating monochromator can also be applies to infrared spectrum regions. The multiple grating monochromator has the advantages of simple structural design, high scanning accuracy of wavelength, wide spectral range, stable performance, easy debugging operation and long service life, and can be used for various spectral analyses and measurements.

Description

A kind of multiple-grating monochrometer that adopts the planar array type ccd detector

The utility model belongs to optical electron device field, is a kind of multiple-grating monochrometer that adopts the planar array type ccd detector.

Optical grating construction is generally having and is carved with many equally spaced grooves on the optical substrate of certain size, photon drops on these strias, because the effect of diffraction, the amplitude and the phase place that will cause each light wave superpose, photon after the reflection just can be lined up in the space regularly by energy or wavelength, and its relational expression is:

Dsin θ _mD and θ in=m λ (1) formula _mThe photon of wavelength X that is the separation of grating and m level respectively is at spatial distributions angle (θ _mBe defined as reflecting the angle between photon direction and the grating normal).In the design of traditional raster monochromator, all fixedly incident of photon and exit slit invariant position, and adopt the θ angle of a physical construction body control grating to rotate, and wavelength is scanned, just can from exit slit, obtain needed monochromaticity photon.Adopt the grating monochromator of said structure, need to solve following two problems in actual use: 1. when monochromator during in the work of the wavelength zone of broad, for wavelength resolution that improves instrument and the signal to noise ratio (S/N ratio) quality that obtains the best, need constantly change grating according to the spectral wavelength district of being worked.2. by formula (1) as can be known, in certain position, θ angle, the diffraction light of the longer wavelength of m=1 and m=2 (or more high order) shorter wavelength can occur simultaneously.Therefore,, need to use one even several piece optical filter at least,, can satisfy the requirement of detected photon monochromaticity the high order diffraction light elimination of m=2 (or more high order) according to the wavelength applications scope of reality.

In present most of commodity monochromator structures, above-mentioned two control function (displacement grating and color filter) are all undertaken by mechanical transmission structure independently, this has just increased the design and the structural complexity of instrument, reduced reliability, bring many inconveniences to use on the other hand, when especially replacing grating, need the wavelength location of system is carried out again precise calibration and adjustment very time-consuming and trouble.For efficient and the precision that improves length scanning, the planar array type ccd detector has been widely used in can replacing the single-photon detector in the grating type monochromator, in the spectral range of broad wavelength is scanned fast.Owing to be subjected to the restriction of the optical grating construction that determined by formula (1),, carry out long covering of high-precision all-wave in the still difficult spectral range that is implemented in broad with a grating and scan even adopt the planar array type ccd detector.Therefore, in present most of commodity CCD grating monochromators, still need to adopt polylith grating and optical filter, can realize high-quality and high-precision length scanning.In above-mentioned commodity CCD grating monochromator design, that is:

Grating G _x→ CCD

Grating G _xFor one or more grating is formed, and,, realize scanning and measurement to wavelength by planar array type CCS detector by the control of mechanical transmission mechanisms such as step motor.Owing to still need to use the moving device in mechanical reception room, weakened the advantage that adopts the planar array type ccd detector to a certain extent.In addition, when the control grating rotates,, need to adopt special limit switch, monochromator is caused damage to prevent that mechanical shift is excessive at the two ends of mechanical shift extreme position length wavelength.This has also increased the complicacy of system design and structure.

The purpose of this utility model is to propose a kind of by the planar array type ccd detector, can realize scanning, simple in structure, service-strong multiple-grating monochrometer fast at full spectral region.

In order to reach above purpose, must be by the following technical solutions: the multiple-grating monochrometer of the utility model design be by polylith sub-gratings and planar array type ccd detector, control computer constitutes, wherein the polylith sub-gratings is combined into a new grating planar so that the equal portions form is parallel, and covering is corresponding to the whole spectral region of the 200-1100nm wavelength coverage of CCD detection, grating planar is perpendicular to the photon incident direction, each grating front end that first block of grating begins is placed a slice high-pass filter respectively, the leading edge consistent wavelength of the cutoff wavelength of each optical filter and corresponding grating is so that the high order diffraction light more than 2 times of elimination grating spectrum district correspondence; Corresponding with optical grating construction, the focal plane of ccd detector also is divided into corresponding a plurality of spectral region, each aliquot number of detector elements evenly is divided into several sub-districts again by the length scanning direction, make the detection unit of each sub-district corresponding with each detected wavelength location, each is surveyed the sub-district and is not disturbed mutually in measurement.System is by computer control.

The nothing machinery displacement multiple-grating monochrometer of the planar array type ccd detector of the utility model design has following excellent results:

Need not any mechanical driving device, just can in the 200-1100nm wavelength coverage, realize high precision and scanning fast that all-wave is long, thereby fill effect and the advantage of having brought into play ccd detector, make that the structure of CCD grating monochromator is very simple and reliable, length scanning precision height, spectral range is wide, stable performance, it is long, user-friendly to be easy to debugging and life-span.Appearance and application along with infrared planar array type detector, this method also can be applied to infrared spectral region at an easy rate, as long as the polylith echelette is combined by principle of the present utility model, realize the fast rapid-result length scanning of full infrared spectral region of no mechanical transmission and displacement.Each piece grating covers corresponding spectral region.Corresponding optical filter is set, the high order diffraction light of m 〉=2 that elimination is corresponding with the grating spectrum district before every block of grating.In the utility model, need to finish CCD and survey accurate location between unit and the wavelength in whole wavelength scanning range, this can measure high-resolution standard line-spectra by going, then by computer fitting, obtain the corresponding relation between each CCD detection unit and the scanning wavelength, just can realize the precise calibration of system, make that the scanning and the control accuracy of wavelength can be better than 0.5nm in full spectrum working range.(if 2000 * 2000 survey first ccd detector, and form compound grating with 5 sub-gratings by different θ angles, and in 200-1100nm spectral region scope, the length scanning precision can be better than 0.1nm).In the long-term use afterwards, monochromator all can be in the reliable duty, and the work of daily servicing can be reduced to minimum, thereby has improved work and scientific research efficient significantly.

Below in conjunction with the drawings and specific embodiments, further describe the utility model.

Fig. 1 is a structural representation of the present utility model;

Fig. 2 is a structure principle chart of the present utility model;

Fig. 3 is three blocks of parallel new gratings that are combined into of grating;

In the accompanying drawing, grating 1 is 1800 lines/mm, and grating 2 is 1200 lines/mm, and grating 3 is 600 lines/mm; Grating 4 is the grating of three grating 1,2,3 parallel compositions, and 5,6 is spherical reflector M ₁, M ₂7,8 are difference entrance slit S ₁With exit slit S ₂9 is light source, and 10 is the planar array type ccd detector, and 11 is the A/D data converter, and 12 is computing machine.

Embodiment, as shown in drawings, stop position in traditional planar array type CCD grating monochromator is cancelled original opto-mechanical drive mechanism.With the corresponding 200-1100nm wavelength coverage of the detector of planar array type CCD in, adopt three sub-gratings 1,2,3 to cover whole spectral region, be respectively:

Grating 1.200-400nm, 1800 lines/mm grating, blaze wavelength is 250nm;

Grating 2.300-600nm, 1200 lines/mm grating, blaze wavelength is 450nm;

Grating 3.600-1200nm, 600 lines/mm grating, blaze wavelength is 750nm; With photon plane of incidence vertical direction, these three blocks of gratings are combined so that trisection is parallel, form a new grating planar, the grating chi that promptly is combined at last is a cun L * L, every block of grating is of a size of (L/3) * L.Each places a slice high-pass filter respectively at the front end of grating 2 and grating 3, is respectively 300nm and 600nm with the cutoff wavelength of the corresponding optical filter of grating, can be with m=2 or more high order diffraction light elimination.According to formula (1), the distance between centers of tracks d of above-mentioned three blocks of gratings is 1: 1.5: 3, and in above-mentioned spectral range, the operation wavelength district of three blocks of gratings is all corresponding to identical θ subtended angle, promptly all in about 21-46 degree scope.Therefore, when photon incides on the grating 4, the diffraction light of its upper, middle and lower trisection will cover different spectral region simultaneously.Then by an optical system, whole diffraction light focussing planes that will have an identical θ subtended angle also trisection are divided into three spectral region in upper, middle and lower, cover 200-400nm, 300-600nm, 200-1100nm wavelength zone respectively.For example adopt 1000 * 1000 to survey unit and shine Si base CCD planar array type detector 10, the spectral region scope is 200-1100nm, and each is surveyed unit and is of a size of 24 * 24 μ m.With photon plane of incidence vertical direction, ccd detector 10 is divided into trisection, that is: each aliquot number of detector elements is 333 * 1000, and is divided into 1000 sub-districts again by the length scanning direction, each sub-district is 333 and surveys unit, and is corresponding with the position of each detected wavelength.Each area of surveying the sub-district is 24 μ m * 0.8cm, does not disturb mutually in measurement.Like this, just can be under the condition of no any mechanical driving device and limit switch, high precision and fast wave long scan that this instrument can be implemented in the 200-1100nm spectral range are measured.

The piece number of the sub-gratings of parallel combination can determine that to spectral range and length scanning precision needs the piece number is many more according to different user in the utility model, and its precision is high more; General available 3-6 piece sub-gratings.And the position of parallel sub grating can exchange.

Claims

1. multiple-grating monochrometer, constitute by polylith grating and planar array type ccd detector, control computer, it is characterized in that the polylith grating is combined into a new grating planar so that the five equilibrium form is parallel, and covering whole spectral region corresponding to the wavelength coverage of ccd detector, grating planar is perpendicular to incident direction; Each piece grating front end is placed the high-pass filter of the high order diffraction light more than 2 times that a slice can elimination grating spectrum district correspondence respectively after first block of grating, the leading edge consistent wavelength of the cutoff wavelength of each optical filter and corresponding grating; Corresponding with optical grating construction, the focal plane of ccd detector also is divided into a plurality of spectral region, each aliquot number of detector elements evenly is divided into several sub-districts again by the length scanning direction, and it is corresponding with each detected wavelength location that each surveys sub-district detection unit, and system is by computer control.

2. multiple-grating monochrometer according to claim 1, the grating piece number that it is characterized in that forming new grating planar is the 3-6 piece.

3. multiple-grating monochrometer according to claim 2 is characterized in that: in the corresponding 200-1100nm wavelength coverage of planar array type ccd detector, adopt three blocks of gratings to cover a rectifier spectral region, be specially:

Grating (1) .200-400nm, 1800 lines/mm grating, blaze wavelength is 250nm;

Grating (2) .300-600nm, 1200 lines/mm grating, blaze wavelength is 450nm;

Grating (3) .600-1200nm, 600 lines/mm grating, blaze wavelength is 750nm;

Front end in grating (2) and (3) is respectively placed a slice high-pass filter respectively, and its cutoff wavelength is respectively 300nm and 600nm;

Corresponding with optical grating construction, the focal plane of ccd detector also is divided into three spectral region in upper, middle and lower that can cover 200-400nm, 300-600nm, 600-1200nm wavelength zone respectively.