CN101813519A - Stray light correction method of spectrograph - Google Patents

Abstract

The invention discloses a method and a device for correcting stray light of a spectrograph. A plurality of color filters capable of being cut in are arranged on a light path between a light signal entering slit and a color dispersion element of the spectrograph, the same light source to be measured is respectively measured when each color filter is cut in and when light filters are not cut in, stray light distributing factors are calculated by the measured spectrum, the stray light error of the light source to be measured or other light sources is corrected and measured by using the stray light distributing factors, and the color filters can also be combined with laser to further correct the stray light; or the color filters and the laser are combined to correct the stray light generated by light radiation outside the measuring waveband of the spectrograph, and the stray light in the measuring waveband of the spectrograph is corrected by using the laser; and the corresponding measurement and control software of the spectrograph comprises a stray light correction program capable of conveniently and rapidly realizing the correction of the stray light. The invention can realize the correction of the stray light in the measuring waveband of the spectrograph and the stray light caused by the light radiation outside the measuring waveband and has convenient operation and is easy to realize high-precision spectral measurement.

Description

Stray light correction method of spectrograph

[technical field]

The invention belongs to the spectroradiometric measurement field, be specifically related to the bearing calibration of stray light of spectrometer.

[background technology]

Spectrometer is widely used in color measuring in order to the spectral power distribution of measuring light radiation, and element is identified, fields such as chemical analysis.Because inevitably there are parasitic light in the scattering that dust or defective cause on the undesirable diffraction of grating, the optical element and the various reflections of instrument internal in the spectrometer.For the rapid spectrometer with detector array, parasitic light is meant that being radiated at certain specific wavelength puts other spectral components on the pairing picture dot, can bring comparatively considerable measuring error.Stray light level is to weigh one of spectrometer performance important techniques index.Adopt the design of careful precision can make parasitic light be reduced to reasonable levels to optical system, for example adopt hermetically-sealed construction, the inner blacking of spectrometer or before optical elements such as collimating mirror and grating, diaphragm etc. is set.But, need further step in order to reach higher precision.

Use stray light correction method also can reduce the error that parasitic light brings, and do not influence measuring speed generally speaking.At present, proofreading and correct stray light of spectrometer with tunable laser is a kind of more feasible method, promptly use the laser of spectrometer measurement tunable laser, calculate the parasitic light distribution factor of the optical radiation of corresponding wavelength at other wavelength place generation parasitic light, it is point spread function, use the spectrum of arbitrary light source to be measured that this point spread function and spectrometer survey, calculate the parasitic light power that each wavelength receives, measured spectra deducts this parasitic light power and obtains comparatively accurate light source light spectrum to be measured.Though this method can significantly reduce parasitic light, improve measuring accuracy, also there are some problems, at first the manufacturing of tunable laser and maintenance cost are high, and general spectrometer manufacturer even Measurement Laboratory are difficult to bear; Secondly this method can only be proofreaied and correct the parasitic light that is brought by the optical radiation in the spectrometer measurement wave band in institute's photometry spectrum, and can not proofread and correct the parasitic light that optical radiation each the wavelength place in the spectrometer measurement wave band outside the spectrometer measurement wave band produces, and in fact, the response wave length scope of the detector of spectrometer is generally wide than the measurement wave band of spectrometer, for example for a spectrometer of measuring visible light, the spectral response range of its detector parasitic light of ultraviolet-visible-infra-red range, particularly infrared part often can be brought than mistake to measurement.

[summary of the invention]

In order to overcome the above-mentioned defective that exists in the prior art, that the present invention aims to provide is easy to operate, can proofread and correct in the spectrometer measurement wave band fast and the method for the parasitic light that extraneous optical radiation brings, and obtains comparatively accurate spectral measurement value.

The present invention mainly realizes above-mentioned purpose by two kinds of main technical scheme.A kind of stray light correction method that is based on color filter, another kind is based on the stray light correction method of laser.

Be characterised in that between the entrance slit of spectrometer and dispersion element, to be provided with based on the stray light correction method of color filter and can cut one or more color filters of light path, and may further comprise the steps:

A) described color filter is cut into one by one on the light path between entrance slit and the dispersion element, measures the spectral power of light source to be measured;

B) when not cutting described color filter, measure the spectral power of same light source to be measured;

C) measurement result according to step a) and step b) calculates the parasitic light distribution factor or the flare correction factor;

This light source to be measured that records when d) not cutting above-mentioned color filter or the spectral power of other light source with parasitic light distribution factor or the correction of the flare correction factor.

Because in spectrometer inside, the optical radiation of a certain wavelength (comprise in the spectrometer measurement scope or scope outer) is incided the probability that produces the parasitic light electric signal in the detection light path of other each wavelength and is remained unchanged substantially, but size can change in proportion along with the light signal power of this wavelength light radiation, this proportionate relationship can be expressed as the parasitic light distribution factor of the optical radiation of this wavelength at other wavelength generation parasitic light, simultaneously also just because of the existence of this ratio, when having other light source of similar spectral power distribution at a certain light source to be measured of measurement or with this light source to be measured, ratio between the parasitic light power that receives in each wavelength place and the measured value at this place also remains unchanged, and this proportionate relationship also can be described as the parasitic light distribution factor.The difference of above-mentioned two parasitic light distribution factor notions is in the former proportionate relationship, and molecule is that spuious light wavelength and denominator are that the wavelength of optical radiation is inequality; And molecule is identical with wavelength in the denominator in the latter's the proportionate relationship.But above-mentioned parasitic light distribution factor can both be used for proofreading and correct the measured value of spectrometer.In arbitrary stage of the production or the application of spectrometer, obtain the parasitic light distribution factor of each wavelength in the spectrometer, just can carry out flare correction and obtain measured value comparatively accurately any measured value.Adopt the parasitic light distribution factor of color filter method measuring light spectrometer among the present invention and the measurement result of spectrometer is proofreaied and correct, to reduce the measuring error that parasitic light brings.

Above-mentioned color filter can be the combination with a kind of color filter or several color filters, promptly be long logical color filter, perhaps be short logical color filter, the logical color filter of perhaps existing length has band-pass filter again, the logical color filter of perhaps existing length has short logical color filter again, perhaps existing band-pass filter has short logical color filter again, and perhaps existing normal open color filter has band-pass filter and short logical color filter again.The logical color filter of described length has cutoff wavelength, and the band of light radiation transmitance that the wavelength ratio cut-off wave is grown up is higher, be called the conducting wave band, and the band of light radiation transmitance of wavelength ratio cut-off wave length is lower, is called by wave band; The logical color filter of described weak point also has cutoff wavelength, and is opposite with long logical color filter, and short logical color filter is the conducting wave band at the wave band of wavelength ratio cut-off wave length, and the long wave band of wavelength ratio cut-off wave is the conducting wave band; Described band-pass filter has cutoff wavelength equally, and two cutoff wavelengths are arranged generally, by the wave band between the wavelength higher transmittance of ratio is arranged two, be called the conducting wave band, and two lower by the wave band transmitance on wavelength both sides, be called by wave band, what deserves to be mentioned is, some band-pass filter can have the higher transmittance of ratio except specifying the logical wave band conducting of band in the long-wave band part.Various color filters, particularly long logical color filter can both buy on the market at an easy rate, so calculates the parasitic light distribution factor with color filter among the present invention and the enforcement ratio of technical scheme that measurement result is proofreaied and correct is easier to.Significant be, the conducting wave band of the color filter that is adopted among the present invention both can be positioned at the measurement wavelength band of spectrometer, also can be outside the measurement wavelength band of spectrometer, the color filter of conducting wave band beyond measurement range can be used for calculating and proofreading and correct the measuring error that the stray light emission outside the spectrometer measurement wavelength band brings.

There is several different methods can be used for calculating the parasitic light distribution factor and measurement result proofreaied and correct, hereinafter will further set forth:

A kind of technical scheme is, comprise one or more long logical color filters in the described color filter, the cutoff wavelength of each long logical color filter is divided into the experimental process wave band with the measurement wave band of spectrometer, lead to color filter and do not cut the spectral power of measuring same light source to be measured when length is led to color filter according to each length of incision, calculate the parasitic light distribute power in each cutoff wavelength sub-band before, and the spectrum power scale of this sub-band of measuring when not cutting long logical color filter compares, and obtains the parasitic light distribution factor in the sub-band before the cutoff wavelength; Spectral power measured value when not cutting long logical color filter deducts itself and the product of parasitic light distribution factor, obtains passing through the spectral power of parasitic light correction.

Particularly, comprise that the individual cutoff wavelength of n (n 〉=1) is λ in the above-mentioned color filter _i(i=1 ... n, λ ₁＜...＜λ _n) the logical color filter of length, the cutoff wavelength of each long logical color filter is divided into several wave bands with the measurement wave band of spectrometer, can be designated as λ _I-1≤ λ＜λ _i, the spectral power of the light source to be measured that records under the individual long logical color filter of i is designated as P _Lf ⁱThe spectral power of the light source to be measured that records when (λ), not cutting above-mentioned any color filter is designated as P _Lf ⁰(λ), according to P _Lf ⁱ(λ) and P _Lf ⁰(λ) calculate the parasitic light that each wavelength produces in each cutoff wavelength wave band of optical radiation before this cutoff wavelength afterwards, and and P _Lf ⁰(λ) value of the wave band before cutoff wavelength is compared, and obtains the parasitic light distribution factor K of each wavelength in the cutoff wavelength wave band before _Lf(λ), the flare correction factor is that unit value subtracts K _Lf(λ);

$K_{\mathrm{lf}}\left(\mathrm{\λ}\right)=\frac{(P_{\mathrm{lf}}^i\left(\mathrm{\λ}\right)-P_{\mathrm{lf}}^0\left(\mathrm{\λ}\right)\·{\mathrm{\τ}}_l^i\left(\mathrm{\λ}\right))/({\mathrm{\τ}}_{\mathrm{lf}}^i-{\mathrm{\τ}}_l^i\left(\mathrm{\λ}\right))}{P_{\mathrm{lf}}^0\left(\mathrm{\λ}\right)},({\mathrm{\λ}}_{i-1}\≤\mathrm{\λ}\≤{\mathrm{\λ}}_i,i=1~n)---\left(1\right)$

Flare correction factor K c _fComputing method (λ) are:

${\mathrm{Kc}}_{\mathrm{lf}}\left(\mathrm{\λ}\right)=1-\frac{(P_{\mathrm{lf}}^i\left(\mathrm{\λ}\right)-P_{\mathrm{lf}}^0\left(\mathrm{\λ}\right)\·{\mathrm{\τ}}_l^i\left(\mathrm{\λ}\right))/({\mathrm{\τ}}_{\mathrm{lf}}^i-{\mathrm{\τ}}_l^i\left(\mathrm{\λ}\right))}{P_{\mathrm{lf}}^0\left(\mathrm{\λ}\right)},({\mathrm{\λ}}_{i-1}\≤\mathrm{\λ}\≤{\mathrm{\λ}}_i,i=1~n)---\left(2\right)$

Wherein, λ ₀Can survey the minimum value of wave band for spectrometer; τ ⁱBe that i long logical color filter is at λ (λ) _I-1≤ λ＜λ _iThe transmitance that scope is interior, because this wave band is the wave band that ends of long logical color filter, transmissivity is very little, under undemanding situation, this value can be changed to 0; τ ⁱ _fBe the transmitance mean value at the conducting wave band of i long logical color filter, under undemanding situation, this value can be changed to 1; Spectrometer can be surveyed the maximal value λ of wave band _MaxExpression is if wherein the cutoff wavelength of any one long logical color filter is greater than λ _Max, then the parasitic light distribution factor only calculates λ _MaxTill; Above-mentioned P _Lf ⁱ(λ) be the measured value of the calibration result when not cutting above-mentioned any color filter.

The parasitic light distribution factor of each wave band that through type (1) or (2) are calculated merges, and obtains (λ ₀≤ λ≤λ _Max) the interior parasitic light distribution factor K of scope _Lf(λ), parasitic light modifying factor Kc _Lf(λ).Correction obtains (λ to measured value when not adding the logical color filter of above-mentioned length through parasitic light ₀≤ λ＜λ _Max) comparatively accurate P in the scope _Clf(λ):

P _ckf(λ)＝(1-K _lf(λ))P ⁰(λ) (3)

Perhaps P _Clf(λ)=Kc _Lf(λ) P ⁰(λ) (4)

In above-mentioned parasitic light distribution factor computing method, the measured value of the main long pass filter of utilization and the logical color filter that do not extend obtains the stray light of the optical radiation of long-wave band in wave band shorter position generation, and is more accurate to finding the solution of parasitic light distribution factor.The parasitic light distribution factor that this method is obtained not only can be revised the measured value of a measured light, and can revise same class have similar spectral characteristic sample measured value and do not need to recomputate the parasitic light distribution factor, therefore particularly suitable when continuous coverage one class sample.But still being limited to, this method measures same or same class sample flare correction measurement.

Second kind of technical scheme is to comprise one or more short logical color filter and/or band-pass filters in the described color filter, the cutoff wavelength of short logical color filter and/or band-pass filter is divided into the experimental process wave band with the measurement wave band of spectrometer, spectral power measured value in the conducting wave band of the spectral power measured value of the wave band before short logical each cutoff wavelength of color filter and/or band-pass filter is coupled together, obtain the spectral power of light source to be measured in whole measurement wave band.The spectral power of the light source to be measured that will record under short logical color filter of incision and/or band-pass filter obtains this wave band flare correction factor divided by the spectral power of not cutting the same light source to be measured that records when weak point leads to color filter or band-pass filter; Spectral power measured value when not cutting logical color filter of described weak point or band-pass filter multiply by the flare correction factor, obtains the spectral power through the parasitic light calibration.

Produce at short-wave band because the main parasitic light in the spectrometer is the optical radiation of long-wave band, therefore, use short logical color filter or band-pass filter effectively to have stoped parasitic light to enter the optical radiation filtering of long-wave band.Spectral power measured value at short logical color filter of incision or band-pass filter is based on the measurement result of using the standard sources calibration under these color filters.

In above-mentioned step d), the similar light source of under the condition that does not add above-mentioned color filter, measuring with described parasitic light distribution factor or the correction of the flare correction factor that has similar spectral power distribution with described light source to be measured.Use above-mentioned color filter piecemeal measure spectrum will certainly reduce measuring speed, the measuring speed of rapid spectrometer particularly, therefore compare in the measurement result of incision when not cutting color filter according to typical case's light source to be measured, obtain the flare correction factor, other and this typical case's light source to be measured has the light source of similar spectral distribution and can measure fast when not cutting above-mentioned color filter.And obtain comparatively accurate measurement result with this flare correction factor correction measured value.

Above-mentioned two kinds of technical schemes can be used simultaneously, and promptly parasitic light distribution factor and the correction calculation that obtains with the logical color filter of above-mentioned length, short logical color filter and band-pass filter can be used simultaneously.

In the bearing calibration of above-mentioned stray light of spectrometer, before the step a) of long logical color filter correction parasitic light or after described step d), can also use a wavelength or an above wavelength laser to proofread and correct parasitic light, the steps include:

A) under the condition of cutting or do not cut described color filter, measure a wavelength or an above wavelength laser respectively with spectrometer, obtain the parasitic light distribution power of laser, calculate the parasitic light distribution factor of the optical radiation of laser corresponding wavelength at other each wavelength generation parasitic light in spectrometer different wave length position;

B) spectral power and the above-mentioned parasitic light distribution factor of the arbitrary light source to be measured that records according to this spectrometer, integrating meter is calculated the received parasitic light power summation from other wavelength on each wavelength in institute's photometry spectral power, and institute's photometry spectral power deducts the spectral power that parasitic light power on each wavelength that calculates obtains comparatively accurate light source to be measured.

Method available expression with the laser-adjusting parasitic light is expressed, in the laser spectrum power with spectrometer measurement, remove the interior value of Wavelength of Laser λ ' that surveys of institute and bandwidth (IB) thereof, the spectral radiant power that records on other wavelength is that parasitic light introduces, wavelength X ' the parasitic light distribution factor K of optical radiation on other wavelength _l ^{λ '}(λ) available following formula calculates:

$K_l^{\mathrm{\λ}\text{'}}\left(\mathrm{\λ}\right)=\frac{P_l^{\mathrm{\λ}\text{'}}\left(\mathrm{\λ}\right)}{\underset{\mathrm{\λ}\text{'}\∈\mathrm{IB}}{\mathrm{\Σ}}{P}_l^{\mathrm{\λ}\text{'}}\left(\mathrm{\λ}\right)},\mathrm{\λ}\∉\mathrm{IB}---\left(5\right)$

In the following formula, P _l ^{λ '}(λ) for the wavelength of spectrometer measurement be the spectral power distribution of λ '.

Expression formula with parasitic light distribution factor correction measurement result is:

$P_{\mathrm{cl}}\left(\mathrm{\λ}\right)=P_l\left(\mathrm{\λ}\right)-\underset{\mathrm{\λ}\text{'}\≠\mathrm{\λ}}{\∫}{K}_l^{\mathrm{\λ}\text{'}}\left(\mathrm{\λ}\right)\·P_l(\mathrm{\λ}\text{'})\mathrm{d\λ}\text{'}---\left(6\right)$

In the following formula, P _l(λ) be the spectral power of any light source to be measured of process spectrometer measurement, P _Cl(λ) be the revised measured value of process.

The laser-adjusting method can be proofreaied and correct tested arbitrarily spectrum, certainly comprise and use the spectrum that records after the color filter, therefore can proofread and correct one by one to the color filter measured value and without the measured value of color filter with the laser-adjusting method, and then carry out color filter by corrected value and proofread and correct once more.

Proofread and correct with the distribution factor of laser measurement parasitic light and to the spectrometer measurement result in theory and can access very accurate measured value, yet, need a large amount of stable laser instruments so that the wavelength interval is enough little to realize accurately measuring in whole measurement wavelength coverage, this has significantly improved the measurement cost.And can only realize the parasitic light that optical radiation produces at other wavelength in the spectrometer measurement scope with laser instrument separately, and can't obtain optical radiation beyond the measurement range to the influence of measured value.Therefore the method that combines with color filter and the laser instrument correction parasitic light that combines is more satisfactory method.

For example short color filter or the band-pass filter of leading to of incision with the interference of stray light of the long-wave band beyond the obstruct spectrometer measurement wave band, measured the parasitic light distribution factor K of the optical radiation of each wavelength of calculating in other wavelength generation by technique scheme _l ^{λ '}(λ), and in order to proofread and correct the spectrum P of the light source to be measured under identical color filter condition, measure _Sbl(λ), obtain comparatively accurate spectral power P _Cl(λ).Further measure the spectrum P that when not adding above-mentioned any color filter, measures light source to be measured ₀(λ), and with P _Cl(λ) and P ₀(λ) the two is compared, and obtains the flare correction factor K _Lsbf(λ), this parasitic light distribution factor can be used for proofreading and correct and measure the spectral power that has other light source of similar spectral characteristic with light source to be measured when not cutting above-mentioned color filter.

Again for example, the P in formula (6) _lCan be to deduct value afterwards with the parasitic light power that the optical radiation that the spectrometer measurement wave band is outer of color filter modification method produces (λ), be example with long logical color filter, and available expression is expressed as:

$P_{\mathrm{cl}}\left(\mathrm{\λ}\right)=P_f^0\left(\mathrm{\λ}\right)-(P_f^l\left(\mathrm{\λ}\right)-P_f^0\left(\mathrm{\λ}\right)\·{\mathrm{\τ}}^l\left(\mathrm{\λ}\right))/({\mathrm{\τ}}_f^l-{\mathrm{\τ}}^l\left(\mathrm{\λ}\right))-\underset{\mathrm{\λ}\text{'}\≠\mathrm{\λ}}{\∫}{K}_l^{\mathrm{\λ}\text{'}}\left(\mathrm{\λ}\right)\·P_l(\mathrm{\λ}\text{'})\mathrm{d\λ}\text{'}---\left(7\right)$

In the formula, P ⁰ _f(λ) for not through the spectral power of any correction, spectrometer records when not extending logical color filter light source to be measured, P _f ^lMeasured value when (λ) leading to color filter for the adding cutoff wavelength length also bigger than the maximum detection wavelength of spectrometer, τ ^l(λ), under undemanding condition, can be changed to 0, τ for this long logical transmitance of color filter in the spectrometer measurement scope ^lBe the transmitance of its conducting wave band of this color filter, under undemanding condition, can be changed to 1.

When adopting scaling light source that spectrometer is calibrated, also should carry out the parasitic light calibration, calibrating method is as follows: obtain spectral response value M (λ) with the spectrometer measurement scaling light source; Use flare correction formula correction M (λ), the spectral response M that obtains proofreading and correct _C(λ), in trimming process, also can use the method M that iterates _C(λ) convergence; Utilize M _C(λ) spectrum sensitivity of calculating rapid spectrometer: $S\left(\mathrm{\λ}\right)=P_S\left(\mathrm{\λ}\right)/M_C\left(\mathrm{\λ}\right),$ Wherein, P _S(λ) be the spectral power distribution of known scaled light source.

Stray light correction method based on laser is characterised in that: one or more color filters that can cut light path are set between the entrance slit of spectrometer and dispersion element, comprise the color filter of conducting wave band beyond the spectrometer measurement wave band in the described color filter, may further comprise the steps:

A) in incision or do not cut and use laser outside the known band of a branch of or multi beam power of spectrometer measurement and wavelength under the condition of described color filter, the corresponding wavelength of the outer laser of described band is calculated the optical radiation parasitic light distribution factor that each wavelength place produces parasitic light in the measurement wave band of spectrometer of the outer laser corresponding wavelength of band outside the scope wave band of spectrometer;

B) color filter of described conducting wave band beyond the spectrometer measurement wave band is cut on the light path between light signal collection device and the dispersion element, measure the spectral power of light source to be measured, according to measurement result and described parasitic light distribution factor, calculate the spectral power of light source to be measured beyond the spectrometer measurement wave band;

C) spectral distribution beyond the spectrometer measurement wave band according to described parasitic light distribution factor and light source to be measured, calculate the parasitic light power that spectrometer measurement wave band optical radiation in addition each wavelength place in the spectrometer measurement wave band produces, the light source of measuring when not cutting described color filter same to be measured or the spectral power of similar light source deduct above-mentioned each wavelength parasitic light power, to proofread and correct the parasitic light error that the outer optical radiation of spectrometer measurement wave band brings to spectral measurement.

The technical program is primarily aimed at the correction of the parasitic light of the optical radiation generation beyond the spectrometer measurement wave band.Owing to can not directly obtain the spectral power of the outer optical radiation of spectrometer measurement wave band, bring difficulty for this part optical radiation of correction.In the technical program, the main color filter that uses conducting the spectrometer measurement wave band outside according to the counter spectral power of releasing the optical radiation outward of spectrometer measurement wave band of the parasitic light information that records, and is proofreaied and correct with the laser-adjusting method afford.

On the basis of the parasitic light error that the optical radiation outside the spectrometer measurement wave band brings, can also be before the above-mentioned step a) or after described step c), measure the parasitic light error that the optical radiation in the wave band brings with laser-adjusting: spectral power is proofreaied and correct the spectrum of using a wavelength of spectrometer measurement or an above wavelength band inner laser under the condition of cutting or do not cut described color filter, the corresponding wavelength of described band inner laser is calculated the optical radiation parasitic light distribution factor that each other wavelength place produces in the spectrometer measurement wave band of band inner laser corresponding wavelength in the measurement wave band of spectrometer; Spectrum with the arbitrary light source to be measured of described spectrometer measurement; Spectrum and described parasitic light distribution factor according to the light source to be measured that records, integrating meter is calculated the parasitic light power summation from other wavelength in the spectrometer measurement wave band that receives on each wavelength, and the spectral power of the light source to be measured of surveying deducts on above-mentioned each wavelength parasitic light power to proofread and correct the parasitic light error.Its calculation expression and formula (5) and formula (6) are similar.

When adopting scaling light source that spectrometer is calibrated, also should carry out the parasitic light calibration, calibrating method is as follows: obtain spectral response value M (λ) with the spectrometer measurement scaling light source; Use flare correction formula correction M (λ), the spectral response M that obtains proofreading and correct _C(λ), in trimming process, also can use the method M that iterates _C(λ) convergence; Utilize M _C(λ) spectrum sensitivity of calculating rapid spectrometer: $S\left(\mathrm{\λ}\right)=P_S\left(\mathrm{\λ}\right)/M_C\left(\mathrm{\λ}\right),$ Wherein, P _S(λ) be the spectral power distribution of known scaled light source.

Above-mentioned scaling light source can be with a kind of light source with being used to measure the standard sources of calculating the parasitic light distribution factor.Above-mentioned standard sources is the standard A light source, and deuterium lamp or other have the light source that continuous spectrum distributes in the wavelength coverage of rapid spectrometer.

For realize above-mentioned based on color filter stray light correction method and/or based on the stray light correction method of laser, the present invention adopts following device technique scheme: a kind of spectrometer, comprise the light signal collection device, entrance slit, dispersion element, probe unit and TT﹠C software, it is characterized in that: the color filter that can cut is set on the light path between described light signal collection device and the dispersion element, comprise the flare correction program in the described TT﹠C software, comprise the parasitic light code in the described flare correction program, be used to obtain the parasitic light distribution factor and/or the flare correction factor, and correction codes, be used to use the measured value of parasitic light distribution factor and/or flare correction factor pair spectrometer to carry out flare correction.

The flare correction program is set in the TT﹠C software of spectrometer, described flare correction program is according to above-mentioned writing based on the stray light correction method of color filter and/or based on the stray light correction method of laser, can make things convenient for the manufacturer and the user of spectrometer to carry out flare correction quickly and accurately, be that spectral measurement is more convenient.Above-mentioned TT﹠C software is embedded in the spectrometer or is upper computer software.

Colour wheel is set, the through hole of uniform one group of color filter and no any color filter on the same radius circumference of colour wheel between above-mentioned entrance slit and the dispersion element; Described colour wheel links to each other with rotating driving device, and this rotating driving device can be in the incident beam between the color filter on the colour wheel or through hole incision light signal collection device and the dispersion element.

The long pass filter physical dimension of above-mentioned each is identical, and the present position is identical in the time of in the incision light path.

Above-mentioned photodetector is a detector array, and promptly described spectrometer is a rapid spectrometer, incides simultaneously on each picture dot of detector array from the dispersed light of optical focusing system.

Above-mentioned photodetector also can be a single channel detector, is provided with exit slit between single channel detector and optical focusing system, the mechanical scanning type spectrometer that promptly described spectrometer is made up of monochromator and photodetector.

The wavelength coverage of above-mentioned spectrometer is that ultraviolet arrives infrared arbitrary wavelength band.

The cutoff wavelength of above-mentioned long pass filter is all in the measurement range of described spectrometer.

The invention has the beneficial effects as follows the parasitic light distribution factor of calculating spectrometer by one group of optical filter meter, and measurement result proofreaied and correct, obtain comparatively accurate measured value, utilize color filter can realize the parasitic light that the optical radiation that exceeds the spectrometer measurement wave band brings is proofreaied and correct, and realize that cost is lower, easy to operate; Also can combine further correction parasitic light with laser, band-pass filter with the logical color filter of duration, improve measuring accuracy.

[description of drawings]

Fig. 1 is for realizing a kind of spectrometer synoptic diagram of the present invention.

Fig. 2 is the synoptic diagram of the logical colour wheel of length in Fig. 1 spectrometer.

Fig. 3 is the light transmittance curve of the group leader's pass filter among Fig. 2.

[embodiment]

Embodiment 1:

Be illustrated in figure 1 as the structure that realizes a kind of spectrometer of the present invention, comprise light signal collection device 1 and optical table 2, comprise entrance slit 3 in the optical table 2, dispersion element 4, detector array 5 and microprocessor 9, between light signal collection device and dispersion element, be provided with colour wheel 7, the through hole 6-4 of uniform one group of color filter 6 and no any color filter on the same radius circumference of colour wheel; Described colour wheel 7 links to each other with rotating driving device 8, can be position in the incident beam between the color filter on the colour wheel 76 or through hole 6-4 incision entrance slit 3 and the dispersion element 4.Microprocessor 9 is electrically connected with host computer 10, the TT﹠C software that cooperates with spectrometer is installed in the host computer 10, TT﹠C software not only can realize conventional controlling of sampling and data processing to spectrometer, also comprised the flare correction program, comprise the parasitic light code that obtains the parasitic light distribution factor and/or the flare correction factor in the described flare correction program, with the correction codes that measured value with parasitic light distribution factor and/or flare correction factor pair spectrometer carries out flare correction, utilize the flare correction program to carry out flare correction to the spectrometer measurement result easily.Different according to the difference of color filter in the spectrometer and the laser that is adopted, the flare correction program is also different.

The measurement range of described spectrometer is 380-800nm, adopts five long logical color filter 6-1 in the spectrometer altogether, its cutoff wavelength (λ ₁... λ ₅) be evenly distributed in the 380-800nm wave band, the light transmittance curve of the logical color filter of described length is as shown in Figure 3.

Measured light comprises at least two samples with similar spectrum.

When measuring the spectrum of certain measured light, adopt following method:

A) rotate colour wheel, 5 cutoff wavelengths are respectively λ _i(i=1,2 ... 5, λ ₁＜λ ₂＜...＜λ ₅) long pass filter be arranged on one by one on the light signal collection device and the light path between the dispersion element of rapid spectrometer, and measure measured light, the spectral power distribution that records under i long logical color filter is P _f ⁱ(λ), measure the spectrum P that under through hole, measures this light source to be measured simultaneously _f ⁰(λ);

B) by the P that records _f ⁱ(λ) and P _f ⁰(λ) calculate parasitic light distribution factor K _f(λ),

$K_f\left(\mathrm{\λ}\right)=\frac{(P_f^i\left(\mathrm{\λ}\right)-P_f^0\left(\mathrm{\λ}\right)\·{\mathrm{\τ}}^i\left(\mathrm{\λ}\right))/({1-\mathrm{\τ}}^i-\left(\mathrm{\λ}\right))}{P_f^0\left(\mathrm{\λ}\right)},({\mathrm{\λ}}_{i-1}\≤\mathrm{\λ}\≤{\mathrm{\λ}}_i,i=1~5)$

λ wherein ₀=380nm, τ ⁱ(λ) be the transmittance of i long pass filter;

C) use K _f(λ) revise the spectral power P of this measured light _f ⁰(λ),

$P_{\mathrm{cf}}\left(\mathrm{\λ}\right)=(1-K_f\left(\mathrm{\λ}\right))P_f^0\left(\mathrm{\λ}\right)$

D) under through hole, measure other samples that have similar spectrum with described measured light, obtain spectral measurement value P _Tt ⁰(λ), with the measured value P of parasitic light correction formula to the similar sample under the through hole _Tt ⁰(λ) carry out flare correction, obtain revised spectral value P _Ctt(λ):

$P_{\mathrm{ctt}}\left(\mathrm{\λ}\right)=(1-K_f\left(\mathrm{\λ}\right))P_{\mathrm{tt}}^0\left(\mathrm{\λ}\right)$

Embodiment 2:

Adopt ultraviolet spectrometer (UVS), the measurement wave band of spectrometer is 200nm～400nm.The logical color filter of the length that cutoff wavelength is 250nm can be set between the slit and grating of spectrometer by switching.During with the ultraviolet spectrum of this spectrometer measurement light source to be measured, can adopt following steps:

A) when not adding unimpeded color filter, measure the ultraviolet spectrum power P _f ⁰(λ), recording spectral power distribution when long logical color filter is set is P _f ^u(λ);

B) by the P that records _f ^u(λ) and P _f ⁰(λ) calculate parasitic light distribution factor K _f(λ),

$K_f\left(\mathrm{\λ}\right)=\frac{(P_f^u\left(\mathrm{\λ}\right)-P_f^0\left(\mathrm{\λ}\right)\·{\mathrm{\τ}}^u\left(\mathrm{\λ}\right))/(1-{\mathrm{\τ}}^u\left(\mathrm{\λ}\right))}{P_f^0\left(\mathrm{\λ}\right)},(200\mathrm{nm}\≤\mathrm{\λ}\≤400\mathrm{nm})$

τ wherein ^u(λ) for the transmittance of long pass filter;

C) use K _f(λ) revise the spectral power P of this measured light _f ⁰(λ),

$P_{\mathrm{cf}}\left(\mathrm{\λ}\right)=(1-K_f\left(\mathrm{\λ}\right))P_f^0\left(\mathrm{\λ}\right),(200\mathrm{nm}\≤\mathrm{\λ}\≤400\mathrm{nm})$

D) under through hole, measure other samples that have similar spectrum with described measured light, obtain spectral measurement value P _Tt ⁰(λ), with the measured value P of parasitic light correction formula to the similar sample under the through hole _Tt ⁰(λ) carry out flare correction, obtain revised spectral value P _Ctt(λ):

$P_{\mathrm{ctt}}\left(\mathrm{\λ}\right)=(1-K_f\left(\mathrm{\λ}\right))P_{\mathrm{tt}}^0\left(\mathrm{\λ}\right)$

Embodiment 3:

The spectrometer of structural similarity among employing and the embodiment 1.The measurement range of spectrometer is that the ultraviolet of 200nm～800nm is between the visible range.During with the ultraviolet spectrum of this spectrometer measurement light source to be measured, can adopt following steps:

A) measure the 5 bundle laser of Wavelength distribution between 400nm～800nm respectively with spectrometer, obtain the spectral power distribution of each Shu Jiguang;

B) calculate the first parasitic light distribution factor of the optical radiation of laser corresponding wavelength according to following formula in other wavelength generation:

$K_l^{\mathrm{\λ}\text{'}}\left(\mathrm{\λ}\right)=\frac{P_l^{\mathrm{\λ}\text{'}}\left(\mathrm{\λ}\right)}{\underset{\mathrm{\λ}\text{'}\∈\mathrm{IB}}{\mathrm{\Σ}}{P}_l^{\mathrm{\λ}\text{'}}\left(\mathrm{\λ}\right)},\mathrm{\λ}\∉\mathrm{IB}$

In the following formula, P _l ^{λ '}(λ) for the wavelength of spectrometer measurement is the spectral power distribution of the laser of λ ', IB is its bandwidth;

C), derive the first parasitic light distribution factor that the optical radiation every the wavelength of 5nm produces at other wavelength by linear interpolation according to the 5 bundle laser parasitic light distribution factors of calculating;

D) being expressed as with the measurement result of the first parasitic light distribution factor correction spectrometer measurement any light source:

$P_{\mathrm{cl}}\left(\mathrm{\λ}\right)=P_l\left(\mathrm{\λ}\right)-\underset{\mathrm{\λ}\text{'}\≠\mathrm{\λ}}{\mathrm{\Σ}}{K}_l^{\mathrm{\λ}\text{'}}\left(\mathrm{\λ}\right)\·P_l(\mathrm{\λ}\text{'})$

E) rotate colour wheel, 5 cutoff wavelengths are respectively λ _i(i=1,2 ... 5,300nm＜λ ₁＜λ ₂＜...＜λ ₅＜800nm) long pass filter is arranged on the light signal collection device and the light path between the dispersion element of rapid spectrometer one by one, and measures measured light, and the spectral power distribution that records under i long logical color filter is P _f ⁱ(λ), measure the spectrum P that under through hole, measures this light source to be measured simultaneously _f ⁰(λ);

F) with the formula correction P in the step d) _f ⁱ(λ) and P _f ⁰(λ), obtain P respectively _Lf ⁱ(λ) and P _Lf ⁰(λ);

G) according to P _Lf ⁱ(λ) and P _Lf ⁰(λ) calculate the long second parasitic light distribution factor of leading under the color filter:

$K_{\mathrm{lf}}\left(\mathrm{\λ}\right)=\frac{(P_{\mathrm{lf}}^i\left(\mathrm{\λ}\right)-P_{\mathrm{lf}}^0\left(\mathrm{\λ}\right)\·{\mathrm{\τ}}^i\left(\mathrm{\λ}\right))/(1-{\mathrm{\τ}}^i\left(\mathrm{\λ}\right))}{P_{\mathrm{lf}}^0\left(\mathrm{\λ}\right)},({\mathrm{\λ}}_{i-1}\≤\mathrm{\λ}\≤{\mathrm{\λ}}_i,i=1~5)$

λ wherein ₀=200nm, τ ⁱ(λ) be the transmittance of i long pass filter;

H) use K _Lf(λ) revise the spectral power P of this measured light _Lf ⁰(λ),

P _clf(λ)＝(1-K _lf(λ))P _lf ⁰(λ)

I) under through hole, measure other samples that have similar spectrum with described measured light, obtain spectral measurement value P _Tt ⁰(λ), this is worth P with the first parasitic light distribution factor correction _Ltt ⁰(λ), proofread and correct P with the second parasitic light distribution factor again _Ltt ⁰(λ), obtain comparatively accurate spectral value P _Cltt(λ).

Embodiment 4:

The spectrometer of structural similarity among employing and the embodiment 1.The measurement range of spectrometer is 400nm～800nm, a cutoff wavelength is set at the logical color filter of the length of 800nm on the colour wheel 1 of spectrometer, and the spectral response range of spectrometer detector is 200nm～1100nm.Have 20 bundle laser simultaneously, wherein 15 bundles are the band inner laser, and Wavelength distribution is in the wavelength band of 400nm～800nm, and 5 bundles are the outer laser of band, and Wavelength distribution is in the wavelength band of 800nm～1100nm.During with the ultraviolet spectrum of this spectrometer measurement light source to be measured, can adopt following steps:

A) with the logical color filter incision of described length light path, measure the 5 bundle laser of Wavelength distribution between 800nm～1100nm respectively with spectrometer, obtain the spectral power distribution of the outer laser of each band;

B) calculate parasitic light distribution factor outside the band that produces on optical radiation each wavelength between 400nm～800nm of the outer laser corresponding wavelength of band according to following formula:

${\mathrm{<figure-callout\; id="1"\; label="K\; w"\; filenames="HSA00000012216600011.png"\; state="\{\{state\}\}">K</figure-callout>}}_w^1\left(\mathrm{\&lambda;}\right)=\frac{P_{\mathrm{wl}}^{\mathrm{\&lambda;}\text{'}}\left(\mathrm{\&lambda;}\right)}{\underset{\mathrm{\&lambda;}\text{'}\&Element;\mathrm{IB}}{\mathrm{\&Sigma;}}{P}_{\mathrm{wl}}^{\mathrm{\&lambda;}\text{'}}\left(\mathrm{\&lambda;}\right)},\mathrm{\&lambda;}\&NotElement;\mathrm{IB}$

In the following formula, P _Wl ^{λ '}(λ) for the wavelength of spectrometer measurement is the spectral power distribution of the laser of λ ', IB is its bandwidth;

C) the outer parasitic light distribution factor of band of calculating according to 5 bundle laser is derived optical radiation parasitic light distribution factor outside the band that other wavelength produces of 800nm～1100nm interval every the wavelength of 5nm by linear interpolation;

D) do not cut the logical color filter of above-mentioned length, measure the 15 band inner lasers of Wavelength distribution between 400nm～800nm respectively, obtain the spectral power distribution of each band inner laser with spectrometer;

E) calculate parasitic light distribution factor in the band that produces on optical radiation each wavelength between 400nm～800nm of band inner laser corresponding wavelength according to following formula:

$K_{\mathrm{nl}}^{\mathrm{\&lambda;}\text{'}}\left(\mathrm{\&lambda;}\right)=\frac{P_{\mathrm{nl}}^{\mathrm{\&lambda;}\text{'}}\left(\mathrm{\&lambda;}\right)}{\underset{\mathrm{\&lambda;}\text{'}\&Element;\mathrm{IB}}{\mathrm{\&Sigma;}}{P}_{\mathrm{nl}}^{\mathrm{\&lambda;}\text{'}}\left(\mathrm{\&lambda;}\right)},\mathrm{\&lambda;}\&NotElement;\mathrm{IB}$

In the following formula, P _Nl ^{λ '}(λ) for the wavelength of spectrometer measurement is the spectral power distribution of the laser of λ ', IB is its bandwidth;

F) parasitic light distribution factor in the band that calculates according to 15 band inner lasers is derived optical radiation parasitic light distribution factor in the band that other wavelength produces of 400nm～800nm interval every the wavelength of 5nm by linear interpolation;

G) with the logical color filter incision of described length light path, with between the 400nm～800nm of spectrometer measurement light source to be measured at spectral power distribution P _Lf(λ);

H) according to P _Lf(λ), derive the spectral power distribution P of this light source to be measured in 800nm～1100nm interval with the outer parasitic light distribution factor of band _Lf' (λ);

I) when not cutting long logical color filter, measure light source to be measured between 400nm～800nm at spectral power distribution P ₀(λ);

J) being expressed as with the measurement result of being with outer parasitic light distribution factor correction spectrometer measurement any light source:

$P_{\mathrm{cwl}}\left(\mathrm{\&lambda;}\right)=P_0\left(\mathrm{\&lambda;}\right)-\underset{\mathrm{\&lambda;}\text{'}\&NotEqual;\mathrm{\&lambda;}}{\mathrm{\&Sigma;}}{K}_{\mathrm{wl}}^{\mathrm{\&lambda;}\text{'}}\left(\mathrm{\&lambda;}\right)\&CenterDot;{P_{\mathrm{lf}}}^{\&prime;}(\mathrm{\&lambda;}\text{'})$

K) with the further measurement result of parasitic light distribution factor in the band, be expressed as:

$P_{\mathrm{cl}}\left(\mathrm{\&lambda;}\right)=P_{\mathrm{cwl}}\left(\mathrm{\&lambda;}\right)-\underset{\mathrm{\&lambda;}\text{'}\&NotEqual;\mathrm{\&lambda;}}{\mathrm{\&Sigma;}}{K}_{\mathrm{nl}}^{\mathrm{\&lambda;}\text{'}}\left(\mathrm{\&lambda;}\right)\&CenterDot;P_{\mathrm{cwl}}(\mathrm{\&lambda;}\text{'})$

P _Cl(λ) be the spectral value of more accurate light source to be measured.

Claims (9)

1. stray light correction method of spectrograph is characterized in that being provided with between the light signal collection device of spectrometer and dispersion element (4) and can cut one or more color filters (6) of light path, and may further comprise the steps:

A) when not cutting described color filter (6), measure the spectral power of light source to be measured;

B) color filter (6) is cut on the light path between entrance slit and the dispersion element, measures the spectral power of same light source to be measured;

C) measurement result according to step a) and step b) calculates the parasitic light distribution factor or the flare correction factor;

This light source to be measured that records when d) not cutting above-mentioned color filter (6) or the spectral power of other light source with parasitic light distribution factor or the correction of the flare correction factor.

2. stray light correction method of spectrograph according to claim 1, it is characterized in that: comprise one or more long logical color filters (6-1) in the described color filter (6), the cutoff wavelength of each long logical color filter (6-1) is divided into the experimental process wave band with the measurement wave band of spectrometer, lead to color filter (6-1) and do not cut the spectral power of measuring same light source to be measured when length is led to color filter (6-1) according to each length of incision, calculate the parasitic light distribute power in each cutoff wavelength sub-band before, and the spectrum power scale of this sub-band of measuring when not cutting long logical color filter (6-1) compares, and obtains the parasitic light distribution factor in the sub-band before the cutoff wavelength; Spectral power measured value in the time of will not cutting long logical color filter (6-1) deducts itself and the product of parasitic light distribution factor, obtains passing through the spectral power of parasitic light correction.

3. stray light correction method of spectrograph according to claim 1 and 2, it is characterized in that: comprise one or more short logical color filter (6-2) and/or band-pass filters (6-3) in the described color filter (6), the spectral power of the light source to be measured that will record under short logical color filter of incision and/or band-pass filter obtains this wave band flare correction factor divided by the spectral power of not cutting the same light source to be measured that records when weak point leads to color filter or band-pass filter; Spectral power measured value when not cutting logical color filter (6-2) of described weak point or band-pass filter (6-3) multiply by the flare correction factor, obtains the spectral power through the parasitic light calibration.

4. stray light correction method of spectrograph according to claim 1, it is characterized in that: in step d), the similar light source of under the condition that does not add above-mentioned color filter, measuring with described parasitic light distribution factor or the correction of the flare correction factor that has similar spectral power distribution with described light source to be measured.

5. stray light correction method of spectrograph according to claim 1 and 2 is characterized in that: before the described step a) or after described step d), use a wavelength or an above wavelength laser to proofread and correct parasitic light, the steps include:

A) under the condition of cutting or do not cut described color filter (6), measure a described wavelength or an above wavelength laser respectively with spectrometer, obtain the parasitic light distribution power of laser, calculate the parasitic light distribution factor of the optical radiation of laser corresponding wavelength at other each wavelength generation parasitic light in spectrometer different wave length position;

B) spectral power and the above-mentioned parasitic light distribution factor of the arbitrary light source to be measured that records according to this spectrometer, integrating meter is calculated the parasitic light power that receives on each wavelength, and the parasitic light power that institute's photometry spectral power deducts on each wavelength obtains through parasitic light calibration spectral power.

6. stray light correction method of spectrograph according to claim 1 and 2, it is characterized in that: when adopting scaling light source that spectrometer is calibrated, elder generation's measurements and calculations go out corresponding parasitic light distribution factor, and be used for proofreading and correct the spectral response value of spectrometer to scaling light source, the spectral response that obtains proofreading and correct, the spectrum sensitivity of the spectral response calibration spectrometer that utilization is proofreaied and correct.

7. stray light correction method of spectrograph, it is characterized in that between the light signal collection device (1) of spectrometer and dispersion element (4), being provided with one or more color filters (6) that to cut light path, comprise the color filter of conducting wave band beyond the measurement wave band of spectrometer in the described color filter (6), and may further comprise the steps:

A) in incision or do not cut and use laser outside the known band of a branch of or multi beam power of spectrometer measurement and wavelength under the condition of described color filter (6), the corresponding wavelength of the outer laser of described band is outside the measurement wave band of spectrometer, obtain with the parasitic light distribution power of outer laser, calculate the optical radiation parasitic light distribution factor that each wavelength place produces parasitic light in the spectrometer measurement wave band of the outer laser corresponding wavelength of band in spectrometer different wave length position;

The spectral power of light source to be measured beyond the spectrometer measurement wave band calculated in the spectral power and the described parasitic light distribution factor of the light source to be measured that records during b) according to the color filter (6) of the described conducting wave band of incision beyond the spectrometer measurement wave band;

C) calculate the parasitic light power that the optical radiation of light source to be measured outside the spectrometer measurement wave band each wavelength place in the spectrometer measurement wave band produces according to described parasitic light distribution factor and light source to be measured at the spectral power beyond the spectrometer measurement wave band, the light source to be measured that records when not cutting described color filter (6) or the spectral power of similar light source deduct the parasitic light power of above-mentioned each wavelength, proofread and correct the parasitic light error that the outer optical radiation of spectrometer measurement wave band brings.

8. stray light correction method of spectrograph according to claim 7, it is characterized in that: before the described step a) or after described step c), make the spectrum of under the condition of cutting or do not cut described color filter (6), using a wavelength of spectrometer measurement or an above wavelength band inner laser, obtain the parasitic light distribution power of described band inner laser, calculate the parasitic light distribution factor of the optical radiation of band inner laser corresponding wavelength at other wavelength place generation parasitic light in spectrometer different wave length position; Spectrum with the arbitrary light source to be measured of described spectrometer measurement; According to the spectrum and the described parasitic light distribution factor of the light source to be measured that records, integrating meter is calculated the parasitic light power that receives on each wavelength, and the spectral power of the light source to be measured of surveying deducts on above-mentioned each wavelength parasitic light power to proofread and correct the parasitic light error.

9. according to claim 7 or 8 described stray light correction method of spectrograph, it is characterized in that: when adopting scaling light source that spectrometer is calibrated, elder generation's measurements and calculations go out corresponding parasitic light distribution factor, and be used for proofreading and correct the spectral response value of spectrometer to scaling light source, the spectral response that obtains proofreading and correct, the spectrum sensitivity of the spectral response calibration spectrometer that utilization is proofreaied and correct.

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