CN102645278B - Radio frequency drive control method for hyper-spectral imager of acousto-optic tunable filter - Google Patents
Radio frequency drive control method for hyper-spectral imager of acousto-optic tunable filter Download PDFInfo
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- CN102645278B CN102645278B CN201210137748.7A CN201210137748A CN102645278B CN 102645278 B CN102645278 B CN 102645278B CN 201210137748 A CN201210137748 A CN 201210137748A CN 102645278 B CN102645278 B CN 102645278B
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Abstract
A radio frequency drive control method for a hyper-spectral imager of an acousto-optic tunable filter includes the following steps of firstly, setting a plurality of working wavebands of the hyper-spectral imager of the acousto-optic tunable filter according to the actual need; secondly, setting integral time of a detector under each of the working wavebands according to the actual need; thirdly, calculating stabilization time of sound waves in the acousto-optic tunable filter when the working wavebands of the hyper-spectral imager of the acousto-optic tunable filter are switched; fourthly, calculating intervals between two adjacent working wavebands from the end time point of the integral time of a front working waveband and the start time point of the integral time of a rear working waveband according to the integral time of the detector and the charge transfer and read time; fifthly, calculating and setting an opening and closing timing sequence of a radio frequency drive according to the integral time, the stabilization time of the sound waves and the integral time intervals between the two adjacent working wavebands; sixthly, setting the start time point of the integral time of the detector according to the stabilization time of the sound waves; and seventhly, finishing radio frequency drive control of the hyper-spectral imager of the acousto-optic tunable filter.
Description
Technical field
The present invention relates to a kind of acousto-optic tunable filter hyperspectral imager radio-frequency driven control method, for optimizing the electronics design of acousto-optic tunable filter hyperspectral imager, improve the overall performance of acousto-optic tunable filter hyperspectral imager.Belong to photoelectric instrument equipment technical field.
Background technology
Acousto-optic tunable filter (Acousto-optic Tunable Filter, AOTF) hyperspectral imager has the advantages such as completely automatically controlled, machinery-free parts, wave band switch flexibly, image taking speed is fast, in fields such as precision agriculture, industrial detection, military detection, has had widely and has applied.AOTF hyperspectral imager is mainly comprised of AOTF, radio-frequency driven, detector and optical mirror slip, wherein, AOTF is a kind of automatically controlled filtering device, comprise piezoelectric transducer, acousto-optic crsytal and sound absorber three parts, radio-frequency (RF) driving signal is converted to sound wave through piezoelectric transducer and enters acousto-optic crsytal, utilize the interaction of sound wave and light wave, monochromic beam diffraction from incident white light out, can be realized to filtering functions.By change, be added in the radio-frequency (RF) driving signal frequency on AOTF, just energy diffraction goes out the monochromatic light of different wave length.AOTF hyperspectral imager utilizes this monochrome diffraction light imaging exactly, by controlling radio-frequency (RF) driving signal frequency shift imaging wavelength, and detector adopts charge-coupled image sensor (Charge Coupled Device, CCD) conventionally, be sensitive chip, to obtain high-quality spectral image data.Because AOTF is that then detector gathers image under different wave length at diffraction different wave length in the same time not, so, under normal circumstances, radio-frequency driven one direct-open, along with the change of radio-frequency (RF) driving signal frequency, service band switches, and when frequency shift is wave band switching, trigger detector and start exposure, after certain integral time, detector electric charge shifts and electric charge reads, thereby realize obtaining of a wave band hypograph, then enter next wave band.Due to radio-frequency driven one direct-open, no matter how signal frequency changes, AOTF diffraction light always exists, to the AOTF of imaging applications, this can produce two problems, and the one, AOTF diffraction light irradiates in detector sensitive chip always, for some sensitive chip, in the process that shifts and read at electric charge, can not realize effective charge accumulation, this section of time internal radiation is invalid in the AOTF of sensitive chip diffraction light simultaneously, and this has caused the waste of radio-frequency (RF) driving signal energy; The 2nd, in sensitive chip charge transfer process, AOTF diffraction light is radiated on sensitive chip, and this can make image produce smear, reduces picture quality.
Summary of the invention
Technology of the present invention is dealt with problems and is: overcome the shortcoming of existing AOTF hyperspectral imager radio-frequency driven control mode, propose a kind of AOTF hyperspectral imager radio-frequency driven control method that reduces power consumption and suppress smear.
Technical solution of the present invention is: propose a kind of AOTF hyperspectral imager radio-frequency driven control method, realize the control of radio-frequency driven switch and be consistent with detector sequential, first, start time detector integrates time point has certain delay with respect to service band point switching time, after sound wave complete stability, carry out again imaging, then, when finish integral time, radio-frequency driven is closed, detector enters electric charge transfer and electric charge reads, through after a period of time, next wave band is opened and switched to radio-frequency driven, then repeat said process.In the whole course of work, having there is shut-in time section in radio-frequency driven, has reduced energy dissipation, and when electric charge shifts, radio-frequency driven is closed simultaneously, and dull thread irradiates in detector sensitive chip, has suppressed image streaking.
A kind of acousto-optic tunable filter hyperspectral imager of the present invention radio-frequency driven control method, its concrete steps are as follows:
Step 1: n service band λ of AOTF hyperspectral imager is set according to the actual requirements
1, λ
2..., λ
n;
Step 2: each service band λ is set according to the actual requirements
icorresponding detector integrates time t
i, wherein, i=1,2 ..., n;
Step 3: while calculating the switching of AOTF hyperspectral imager service band according to the propagation principle of sound wave in AOTF, Δ t stabilization time of sound wave;
Step 4: calculate the time interval Δ t' between the end time integral time point of i wave band and the start time integral time point of i+1 wave band according to type photodetector and mode of operation
i, wherein, i=1,2 ..., n;
Step 5: the t arranging according to step 2
i, step 3 calculate Δ t and step 4 calculate Δ t'
i, each service band λ is set
iunder, radio-frequency driven is first opened, and the opening time is spaced apart t
i+ Δ t, then close, the shut-in time is spaced apart Δ t'
i-Δ t, wherein, i=1,2 ..., n;
Step 6: the Δ t calculating according to step 3, arranges each service band λ
iunder, start time detector integrates time point postpones Δ t than radio-frequency driven output signal start time point, wherein, i=1,2 ..., n;
Step 7: complete the control of AOTF hyperspectral imager radio-frequency driven according to step 5 and step 6.
Wherein, the n described in step 1 service band λ
1, λ
2..., λ
ncan be set to uniformly-spaced continuous sweep form, or be set to any switch forms of unequal interval wave band, or be set to the form that segmentation uniformly-spaced scans.
Wherein, the detector integrates time t described in step 2
isetting should make AOTF hyperspectral imager consistent in the response of each wave band, even if η (λ
i) Q (λ
i) t
ifor constant, in formula, η (λ
i) be that AOTF is in wavelength X
ithe diffraction efficiency at place, Q (λ
i) be that detector is in wavelength X
ithe quantum efficiency at place, i=1,2 ..., n.
Wherein, the service band described in step 3 switch time sound wave stabilization time Δ t computing method as follows:
In formula, L
afor acousto-optic crsytal in AOTF is along the length of Acoustic Wave Propagation direction, V
afor the velocity of propagation of sound wave in AOTF acousto-optic crsytal.
Wherein, the time interval Δ t' between start time integral time of end time integral time of i wave band described in step 4 point and i+1 wave band point
i, in formula, i=1,2 ..., n, its computing method are as follows:
1. determine type photodetector, comprise interline transfer type CCD, frame transfer type CCD and full frame type CCD;
2. determine detector mode of operation, comprise serial mode and parallel schema, wherein, full frame type CCD only has serial mode;
3. according to type photodetector and mode of operation, calculate the time interval Δ t' between the end time integral time point of i wave band and the start time integral time point of i+1 wave band
i: for interline transfer type CCD and the frame transfer type CCD of serial mode, time interval Δ t'
ifor
Δt'
i=Δt
trans+Δt
read
In formula, Δ t
transfor detector charge transfer time, Δ t
readfor detector electric charge readout time, for interline transfer type CCD and the frame transfer type CCD of parallel schema, when be greater than readout time integral time, time interval Δ t'
ifor
Δt'
i=Δt
trans
For interline transfer type CCD and the frame transfer type CCD of parallel schema, when be less than readout time integral time, time interval Δ t'
ifor
Δt'
i=Δt
trans+Δt
read-t
i+1
In formula, t
i+1be the integral time of i+1 wave band, when i=n, t
i+1, for full frame type CCD, only there is serial mode in=-Δ t, time interval Δ t'
ifor
Δt'
i=Δt
trans_read
In formula, Δ t
trans_readfor full frame type CCD electric charge shifts and readout time.
Wherein, the radio-frequency driven described in step 5 is at service band λ
iunder, first open t
i+ Δ t, then close Δ t'
i-Δ t, opens when then carrying out wave band switching again, enters next service band, and total duration of each wave band is t
i+ Δ t+ Δ t'
i-Δ t=t
i+ Δ t'
i, wherein, i=1,2 ..., n.
The present invention's advantage is compared with prior art:
(1) adopt the radio-frequency (RF) driving signal of switch, improved the capacity usage ratio of radio-frequency (RF) driving signal, be particularly useful for the large power consumption AOTF such as infrared and heavy caliber, and the low situation of AOTF diffraction light energy during fast imaging;
(2) in the time range shifting at detector electric charge, radio-frequency (RF) driving signal is closed, and dull thread irradiates in sensitive chip, has suppressed image streaking, has improved picture quality.
Accompanying drawing explanation
Fig. 1 is the workflow diagram of a kind of acousto-optic tunable filter hyperspectral imager of the present invention radio-frequency driven control method;
Fig. 2 is adjacent two the waveband integral time interval Δ t' that adopt the AOTF hyperspectral imager of serial mode frame transfer type CCD in the present invention
icalculating schematic diagram.
In figure, symbol description is as follows:
N: operating wave hop count;
λ
i(i=1,2 ..., n): service band;
T
i(i=1,2 ..., n): the detector integrates time under each service band;
Δ t: when service band switches, the stabilization time of sound wave;
Δ t'
i(i=1,2 ..., n): under adjacent two service bands, the interval of previous end time waveband integral time point and rear start time waveband integral time point;
Δ t
trans: detector charge transfer time;
Δ t
read: detector electric charge readout time.
Embodiment
For a kind of AOTF hyperspectral imager of the present invention radio-frequency driven control method is better described, AOTF hyperspectral imager selects serial mode frame transfer type CCD as detector, sees Fig. 1, the present invention includes following steps:
Step 1: 100 service bands of AOTF hyperspectral imager are set according to the actual requirements, and are set to uniformly-spaced continuous sweep form, i.e. λ
1, λ
2..., λ
100one-tenth is spacedly distributed;
Step 2: each service band λ is set according to the actual requirements
icorresponding detector integrates time t
i, in setting up procedure, in order to make AOTF hyperspectral imager consistent in each wave band response, need be according to AOTF in wavelength X
idiffraction efficiency (the λ at place
i) and detector in wavelength X
iquantum efficiency Q (the λ at place
i), calculate each wave band lower integral time t
irelativeness, make η (λ
i) Q (λ
i) t
ifor constant, then, according to the size of extraneous light intensity, signal to noise ratio (S/N ratio) and picking rate, require to arrange t
ioccurrence, in formula, i=1,2 ..., 100;
Step 3: while calculating the switching of AOTF hyperspectral imager service band according to the propagation principle of sound wave in AOTF, Δ t stabilization time of sound wave: when service band switches, radio-frequency (RF) driving signal frequency change, thereby sound wave frequency in acousto-optic crsytal is changed, when sound wave is transmitted to relative one side from acousto-optic crsytal one side, have certain hour, within this period, there is the sound wave after sound wave and the wave band switching before wave band switches, therefore, sound wave is now unsettled, only have and be transmitted to completely after relative one side when sound wave, sound wave is complete stability, so the travel-time of sound wave is Δ t stabilization time, ?
In formula, L
afor acousto-optic crsytal in AOTF is along the length of Acoustic Wave Propagation direction, V
afor the velocity of propagation of sound wave in AOTF acousto-optic crsytal;
Step 4: calculate the time interval Δ t' between the end time integral time point of i wave band and the start time integral time point of i+1 wave band according to type photodetector and mode of operation
i: AOTF hyperspectral imager adopts serial mode frame transfer type CCD as detector, its work schedule as shown in Figure 2, its bend part is the time period that occurs image streaking, within this period, the irradiation of light can cause image streaking, according to detector electric charge, shifts and can calculate Δ t' readout time
ifor
Δt'
i=Δt
trans+Δt
read
In formula, Δ t
transfor detector charge transfer time, Δ t
readfor detector electric charge readout time, wherein, i=1,2 ..., 100;
Step 5: the t arranging according to step 2
i, step 3 calculate Δ t and step 4 calculate Δ t'
i, each service band λ is set
iunder, radio-frequency driven is first opened, and the opening time is spaced apart t
i+ Δ t, then close, the shut-in time is spaced apart Δ t'
i-Δ t, opens when then carrying out wave band switching again, enters next service band, and total duration of each wave band is t
i+ Δ t+ Δ t'
i-Δ t=t
i+ Δ t'
i, in formula, i=1,2 ..., 100;
Step 6: the Δ t calculating according to step 3, arranges each service band λ
iunder, start time detector integrates time point postpones Δ t than radio-frequency driven output signal start time point, through t
iwith Δ t'
iafter, complete obtaining of a wave band hypograph, then enter section integral time of next wave band hypograph, in formula, i=1,2 ..., 100;
Step 7: complete the control of AOTF hyperspectral imager radio-frequency driven according to step 5 and step 6.
Claims (8)
1. an acousto-optic tunable filter hyperspectral imager radio-frequency driven control method, is characterized in that: the method concrete steps are as follows:
Step 1: n service band λ of AOTF hyperspectral imager is set according to the actual requirements
1, λ
2..., λ
n;
Step 2: each service band λ is set according to the actual requirements
icorresponding detector integrates time t
i, wherein, i=1,2 ..., n;
Step 3: while calculating the switching of AOTF hyperspectral imager service band according to the propagation principle of sound wave in AOTF, Δ t stabilization time of sound wave;
Step 4: calculate the time interval Δ t ' between the end time integral time point of i wave band and the start time integral time point of i+1 wave band according to type photodetector and mode of operation
i, wherein, i=1,2 ..., n;
Step 5: the t arranging according to step 2
i, step 3 calculate Δ t and step 4 calculate Δ t '
i, each service band λ is set
iunder, radio-frequency driven is first opened, and the opening time is spaced apart t
i+ Δ t, then close, the shut-in time is spaced apart Δ t '
i-Δ t, wherein, i=1,2 ..., n;
Step 6: the Δ t calculating according to step 3, arranges each service band λ
iunder, start time detector integrates time point postpones Δ t than radio-frequency driven output signal start time point, wherein, i=1,2 ..., n;
Step 7: complete the control of AOTF hyperspectral imager radio-frequency driven according to step 5 and step 6.
2. a kind of acousto-optic tunable filter hyperspectral imager radio-frequency driven control method according to claim 1, is characterized in that: the n described in step 1 service band λ
1, λ
2..., λ
nbe set to uniformly-spaced continuous sweep form.
3. a kind of acousto-optic tunable filter hyperspectral imager radio-frequency driven control method according to claim 1, is characterized in that: the n described in step 1 service band λ
1, λ
2..., λ
nbe set to any switch forms of unequal interval wave band.
4. a kind of acousto-optic tunable filter hyperspectral imager radio-frequency driven control method according to claim 1, is characterized in that: the n described in step 1 service band λ
1, λ
2..., λ
nbe set to the form that segmentation uniformly-spaced scans.
5. a kind of acousto-optic tunable filter hyperspectral imager radio-frequency driven control method according to claim 1, is characterized in that: the detector integrates time t described in step 2
isetting should make AOTF hyperspectral imager consistent in the response of each wave band, even if η (λ
i) Q (λ
i) t
ifor constant, in formula, η (λ
i) be that AOTF is in wavelength X
ithe diffraction efficiency at place, Q (λ
i) be that detector is in wavelength X
ithe quantum efficiency at place, i=1,2 ..., n.
6. a kind of acousto-optic tunable filter hyperspectral imager radio-frequency driven control method according to claim 1, is characterized in that: when service band described in step 3 switches sound wave stabilization time Δ t computing method as follows:
In formula, L
afor acousto-optic crsytal in AOTF is along the length of Acoustic Wave Propagation direction, V
afor the velocity of propagation of sound wave in AOTF acousto-optic crsytal.
7. a kind of acousto-optic tunable filter hyperspectral imager radio-frequency driven control method according to claim 1, is characterized in that: the time interval Δ t ' between the start time integral time point of the end time integral time point of i wave band described in step 4 and i+1 wave band
i, in formula, i=1,2 ..., n, its computing method are as follows:
1. determine type photodetector, comprise interline transfer type CCD, frame transfer type CCD and full frame type CCD;
2. determine detector mode of operation, comprise serial mode and parallel schema, wherein, full frame type CCD only has serial mode;
3. according to type photodetector and mode of operation, calculate the time interval Δ t ' between the end time integral time point of i wave band and the start time integral time point of i+1 wave band
i: for interline transfer type CCD and the frame transfer type CCD of serial mode, time interval Δ t '
ifor
Δt′
i=Δt
trans+Δt
read
In formula, Δ t
transfor detector charge transfer time, Δ t
readfor detector electric charge readout time, for interline transfer type CCD and the frame transfer type CCD of parallel schema, when be greater than readout time integral time, time interval Δ t '
ifor
Δt′
i=Δt
trans
For interline transfer type CCD and the frame transfer type CCD of parallel schema, when be less than readout time integral time, time interval Δ t '
ifor
Δt′
i=Δt
trans+Δt
read-t
i+1
In formula, t
i+1be the integral time of i+1 wave band, when i=n, t
i+1, for full frame type CCD, only there is serial mode in=-Δ t, time interval Δ t '
ifor
Δt′
i=Δt
trans_read
In formula, Δ t
trans_readfor full frame type CCD electric charge shifts and readout time.
8. a kind of acousto-optic tunable filter hyperspectral imager radio-frequency driven control method according to claim 1, is characterized in that: the radio-frequency driven described in step 5 is at service band λ
iunder, first open t
i+ Δ t, then close Δ t '
i-Δ t, opens when then carrying out wave band switching again, enters next service band, and total duration of each wave band is t
i+ Δ t+ Δ t '
i-Δ t=t
i+ Δ t '
i, wherein, i=1,2 ..., n.
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| CN103728019B (en) * | 2013-12-19 | 2015-10-21 | 南京邮电大学 | A kind of spectral measurement device based on acoustooptic modulation and spectral measurement method |
| CN105136295B (en) * | 2015-09-17 | 2017-03-29 | 中北大学 | The uneven solution of spectrum and device in a kind of same width figure of AOTF |
| LU93098B1 (en) * | 2016-06-03 | 2018-01-22 | Leica Microsystems | Method for adjusting the intensity of a light beam in an optical arrangement and associated optical arrangement |
| CN107024283A (en) * | 2017-05-04 | 2017-08-08 | 金华职业技术学院 | A kind of method for measuring black matrix thermodynamic temperature |
| CN107462329B (en) * | 2017-07-28 | 2019-02-22 | 合肥美亚光电技术股份有限公司 | Multispectral camera, multispectral imaging device and control method |
| CN107478218B (en) * | 2017-08-29 | 2019-08-09 | 上海航天控制技术研究所 | A kind of star sensor can be changed turnover rate image acquisition and processing unit and method |
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| US5120961A (en) * | 1990-03-16 | 1992-06-09 | Infrared Fiber Systems, Inc. | High sensitivity acousto-optic tunable filter spectrometer |
| JP4565779B2 (en) * | 2001-08-14 | 2010-10-20 | 富士通株式会社 | Acousto-optic tunable filter |
| CN101131349B (en) * | 2006-08-24 | 2010-04-21 | 河南工业大学 | Non-dispersive whole-static method for non-fluorescent object spectral measurement |
| CN101561388A (en) * | 2008-04-18 | 2009-10-21 | 中国科学院上海技术物理研究所 | Acousto-optic tunable filter imaging spectrometer |
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