[background technology]
Spectrometer distributes in order to the spectral power distribution of measuring light, is widely used in fields such as color measuring, element evaluation, chemical analysis.Stray light level is an important parameter in the spectrometer, so-called parasitic light is meant that the optical radiation of wrong wavelength (non-respective signal optical wavelength) is radiated at the signal that is produced on the detector picture dot, this parameter is all extremely important for all application of spectrometer, and especially it is more outstanding to the influence of measurement result when following situation:
Sample is the line-spectra emission or has a large amount of radiationless distribute power zone that in tested wavelength coverage if parasitic light makes instrument produce non-zero response in empty spectral radiance distributed areas, measurement result just can be regarded as has increased white light;
Spectral radiant energy is along with wavelength variations when very fast, and the near field interference of stray light of wavelength can produce considerable influence to measurement result on every side;
Adopt the standard A light source that spectrometer is calibrated, the energy of standard A light source at the 780mm place is 25 times more than at the 380nm place, so in calibration, parasitic light will make instrument over-evaluate the response at 380nm place.
Usually parasitic light has following main source: the surrounding environment optical radiation; The reflected light that scattered light that the optical element defective is produced or non-optical element produce; Overlapping between different diffraction level time.The design of careful precision can make parasitic light be reduced to reasonable levels, for example adopts 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.The simplest improving one's methods is exactly to adopt band-pass filter to cut down spectral component, the method of double monochromator can reach higher precision in addition, and present color filter and double monochromator method are mainly used in the spectrometer of mechanical scanning type, as if how to be applied in the rapid spectrometer that adopts detector array very difficultly, this also makes one of parasitic light control index become a limitation of rapid spectrometer.
The method that reduces at present parasitic light in the rapid spectrometer that uses detector array is to use long pass filter on some picture dot at detector array, there is limitation in this kind method: at first, and the only generation of parasitic light when the receiving end of dispersed light uses optical filter can not effectively stop incident beam to be propagated in optical table; Secondly, though long pass filter has limited the high order diffraction light to a certain extent, but for spectral distribution such as the standard A light source is weak in the shortwave portion of energy like that, long wave is partly stronger, the parasitic light of long wave part can bring very big error to the measurement of short wavelength's part, thus influence calibration or measurement result.
[summary of the invention]
In order to overcome the above-mentioned defective that exists in the prior art, the utility model provides a kind of low stray light rapid spectrometer, relatively the spectral power distribution of traditional mechanical scan method measuring samples faster; And realize the purpose that same class sample is accurately measured fast.
In order to achieve the above object, the utility model adopts following technical scheme:
A kind of low stray light rapid spectrometer, comprise light signal collection device and optical table, optical table is a cavity, comprise entrance slit in the optical table, dispersion element, optical focusing system and detector array and photoelectric control and adjusting disposal system is characterized in that comprising that logical colour wheel of band and band lead to the rotating driving device of colour wheel, the through hole of uniform one group of band-pass filter and no any color filter on the same radius circumference of the logical colour wheel of band.The light signal collection device is sent to the light signal that collects the optical table inside of described low stray light rapid spectrometer by an entrance slit, the logical colour wheel of band is arranged between light signal collection device and the dispersion element, pass through rotating driving device, the logical colour wheel of band can rotate also in the light beam between corresponding band-pass filter or through hole incision light signal collection device and the dispersion element, further incide dispersion element through the incident beam behind through hole or the band-pass filter, described dispersion element is to described incident beam beam split, and by optical focusing system the picture of dispersion spectrum projected on the block array detector.
The band-pass filter of any amount between two to 20 is arranged in one group of above-mentioned band-pass filter, and the conducting wave band of above-mentioned band-pass filter overlaps from beginning to end, and covers whole wavelength coverage to be measured.
Comprise the blind hole of a complete lighttight fast gate action on the logical colour wheel of above-mentioned band, the position of the position of blind hole and above-mentioned band-pass filter or through hole is suitable, and the logical colour wheel of rotating band can be cut blind hole in the incident beam.When blind hole was worked, incident beam can not enter dispersion element, and detector is not worked.
Also comprise neutral light damping plate on the logical colour wheel of above-mentioned band, the position of the position of neutral light damping plate and above-mentioned band-pass filter or through hole is suitable, and the logical colour wheel of rotating band can be in the neutral light damping plate incision incident beam.Above-mentioned light damping plate also can be between logical colour wheel of band and dispersion element or in the light path between logical colour wheel of band and the entrance slit, light damping plate wheel disc and rotating driving device thereof are set, uniform some neutral light damping plates and a through hole on the same radius circumference of light damping plate wheel disc; Rotation light damping plate wheel disc can be corresponding neutral light damping plate or through hole incision light path.
When neutral light damping plate was worked, the light intensity of incident beam was weakened, and neutral light damping plate can be used for improving the measurement dynamic range of rapid spectrometer.The transmissivity of neutral light damping plate still has spectral selectivity.Use neutral light damping plate to calibrate to described low stray light rapid spectrometer.
In the above-mentioned low stray light rapid spectrometer, in the place ahead of described detector array the linear variable color filter is set, described linear variable color filter is logical or the short logical or band-pass filter of a group leader, is used for reducing the interference of parasitic light and high order diffraction light.
The rotating driving device of logical colour wheel of above-mentioned band and light damping plate wheel disc is a band reduction gear or not with stepper motor, servomotor or the direct current generator of reduction gear.
Above-mentioned dispersion element is grating or prism, and described grating is the concave diffraction grating of plane diffraction grating or the correction of band flat field, and according to the difference of the groove generation type on the grating, described grating is holographic grating and ruling grating.The concave diffraction grating of band flat field correction can serve as optical focusing system, realizes two kinds of functions of beam split and optical focus simultaneously.
Above-mentioned detector array is a charge-coupled image sensor, photodiode array, CMOS linear imaging detector, InGaAs array image-forming detector.
Comprise optical mirror on the light path in the optical table of above-mentioned low stray light rapid spectrometer between entrance slit and the dispersion element, incident beam is reflected to dispersion element through optical mirror.
Also can comprise collimator apparatus in the optical table of above-mentioned low stray light rapid spectrometer, collimator apparatus is on the light path between entrance slit and the dispersion element, the incident beam of dispersing is converted into parallel beam through collimator apparatus, is inciding on the grating by beam split.
Can comprise the detector plated film in the optical table of above-mentioned low stray light rapid spectrometer, in order to strengthen the sensitivity of detector array at ultraviolet or other wave band.
The logical color filter of length that can comprise be used to disappear secondary or three grades of light in the optical table of above-mentioned low stray light rapid spectrometer.
Above-mentioned microprocessor can be realized the control of instrument and the output of Signal Processing and measurement result separately, also can be electrically connected with computer, and carry out exchanges data with it, finishes corresponding function by computer.
The measurement range of this low stray light rapid spectrometer is the visible light wave range of 380nm~780nm, or ultraviolet-visible-near-infrared band.
Compared with prior art, advantage of the present utility model has been to overcome the limitation of rapid spectrometer aspect parasitic light.Method by the band-pass filter group effectively reduces interference of stray light; The sample that same class is had similar spectral power distribution, can be by accurate measurement and two kinds of methods of the fast survey of full spectrum are measured a typical sample respectively piecemeal, obtain the parasitic light modifying factor, as long as other similar samples are fast survey of once full spectrum, result with software just can be composed accurate measurement entirely to the measurement result correction measures fast and accurately.
[embodiment]
As shown in Figure 1, low stray light rapid spectrometer of the present invention, comprise light signal collection device 1 and optical table 2, light signal collection device 1 is sent to spectrometer inside to the light signal that collects by an entrance slit 3, a logical colour wheel 6 of band is set in described spectrometer inside, the logical colour wheel 6 of band as shown in Figure 2, on the logical colour wheel 6 of band one group of band-pass filter 6-1 is arranged, a through hole 6-2, a blind hole 6-3 and a neutral light damping plate 6-4, under the drive of drive motor 9, the logical colour wheel 6 of described band rotates, corresponding band-pass filter 6-1, through hole 6-2, blind hole 6-3 or neutral light damping plate 6-4 go in the incident beam to be measured, during blind hole 6-3 work, incident beam can not arrive dispersion element 4, detector array 5 is not worked, incident beam is through through hole 6-2, color filter 6-1 or neutral light damping plate 6-4 laggard step into and are mapped to dispersion element 4, described dispersion element 4 is described incident beam chromatic dispersion, and by optical focusing system 7 picture of dispersion spectrum is projected on the block array detector 5, be provided with the linear variable color filter 8 that the logical color filter of a group leader is formed before the detector array 5.Described low stray light rapid spectrometer inside also comprises a microprocessor and a peripheral circuit that utilizes prior art and design and produce, and is used to control duty and the rotation of the logical colour wheel 6 of band and the detectable signal of adjusting, conversion and transmission array of spectrometer.Described low stray light rapid spectrometer also comprises supporting with it software, is used for handling and the analysis to measure result.Dispersion element 4 described in the legend is concave diffraction gratings of band flat field correction, this concave diffraction grating compatibility the function of optical focusing system 7, directly the monochromatic light of different wave length is projected on the picture dot of detector array 5, the rotating driving device of the logical colour wheel of described band is a stepper motor, described detector array 5 is charge coupled device ccds, the monochromatic opto-electronic conversion of the corresponding different wave length of the CCD pixel of diverse location in same rapid spectrometer, described microprocessor links to each other with computer, and data communication interface is the usb data communication port.
Among the described one group of band-pass filter 6-1 of present embodiment five band-pass filter 6-1 are arranged, the conducting wave band of band-pass filter 6-1 overlaps from beginning to end, and covers whole wavelength coverage to be measured.Incident beam is through behind some band-pass filter 6-1, and the light beam that becomes corresponding narrow spectral coverage incides diffraction grating 4 beam split; Incident beam remains unchanged through through hole 6-2 spectral radiant power; And incident beam reduces through spectral radiant power behind the neutral light damping plate 6-4 is whole, but the transmissivity of neutral light damping plate still has spectral selectivity.
Use this low stray light spectrometer can be to sample measurement under three kinds of situations, i.e. accurate measurement single sample piecemeal, full spectrum is fast surveys the sample that single sample and quick accurate measurement one class of full spectrum have similar spectral power distribution distribution.Calibration to described spectrometer also comprises two kinds: the standard A light source is calibrated piecemeal through the logical color chips 6-1 of band, the standard A light source is calibrated in full spectral coverage scope, and the calibration in the full spectral coverage scope includes irradiating light beam through through hole 6-2 and two kinds of situations of neutral light damping plate 6-4.