CN1963655A - Method for controlling frequency conversion in large dynamic range without blind area of rotary disk mechanical shutter - Google Patents
Method for controlling frequency conversion in large dynamic range without blind area of rotary disk mechanical shutter Download PDFInfo
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- CN1963655A CN1963655A CN 200610165087 CN200610165087A CN1963655A CN 1963655 A CN1963655 A CN 1963655A CN 200610165087 CN200610165087 CN 200610165087 CN 200610165087 A CN200610165087 A CN 200610165087A CN 1963655 A CN1963655 A CN 1963655A
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Abstract
This invention relates to rotation mechanic shot large dynamic range without blind area variable frequency control method according to shot work frequency to make the shot work in large range, which comprises the following steps: firstly computing mechanic shot to work normally in work frequency range according to disc mechanic shot space occupancy and different work distance; then computing normal work frequency middle value as certain detection distance for best work frequency; finally according to real conditions to limit and need several mechanic shot control pattern to select one.
Description
Technical field
The invention belongs to the optical engineering technical field, the application process that relates to a kind of rotary disk mechanical shutter of control bundle break-make, relate in particular to a kind of method for controlling frequency conversion in large dynamic range without blind area of rotary disk mechanical shutter, can under application scenarioss such as laser radar, obtain enough big range sensing dynamic range.
Background technology
In applications such as laser radar, laser ranging, space laser communication, need survey the target of a distance.Its working system all is to launch a laser pulse earlier, postpones to receive the light signal that returns from target with photodetector behind the certain hour, obtains effective information from heliogram.Usually several kilometers to several thousand kilometers of target range detectors to be measured, the pulse repetition rate that needs arrives the hundreds of hertz tens.In these application scenarios, usually adopt in the Laser emission receiving trap a vitals be the high-speed, high precision rotary disk mechanical shutter, be used for the break-make of control bundle.The primary structure of rotary disk mechanical shutter is a light tight disk that perforate or fluting are arranged.Light beam incides on the disk, runs into the hole or groove just passes through, otherwise just is turned off.Disk just rotated to realize turning on and off of certain repetition frequency.The advantage of rotating disc type mechanical shutter is to reach completely and turns on and off, and does not influence the picture element of transmitted beam, can adapt to all optical maser wavelength.
The patent of invention " high repetition frequency high precision rotary disk mechanical shutter device (number of patent application 03149542.7; applying date 2003.07.16; publicity CN1570569; publicity day 2005.01.26) " of application such as Li Xinyang discloses a kind of rotary disk mechanical shutter device that light signal is carried out the control of high repetition frequency high precision switch.A tight rotary disc frivolous, that plurality of opening is arranged is fixed on the spindle nose of motor by locknut and axle sleeve.By suitable choice structure parameter, precision is set the switching time that this rotary disk mechanical shutter device can reach the switch repetition frequency of KHz and microsecond level simultaneously.Fig. 1 is that the typical case of this invention uses: the structural representation of a quaterfoil rotary disk mechanical shutter.Method for controlling frequency conversion of the present invention is promptly at the work of this kind rotary disk mechanical shutter.
The patent of invention " a kind of rotary disk mechanical shutter synchronous time sequence control method and application thereof (number of patent application 03149543.5; applying date 2003.07.16; publicity CN1570570; publicity day 2005.01.26) " of application such as Li Xinyang, disclose a kind of rotary disk mechanical shutter synchronous time sequence control method, received the emission sequential of gating pulse laser instrument in the electro-optical system and the exposure time series of photodetector synchronously in the pulse laser emission.Under this rotary disk mechanical shutter control mode, the frequency of operation of mechanical shutter configures in advance, and frequency of operation is changeless in the course of the work.
The mechanical shutter of steady job frequency can be in certain detection range dynamic range operate as normal.But under some scene, the variable in distance of detection is very big.For example in the process that Space Object in Orbit is surveyed, detection range changes to the hundreds of kilometer from several thousand kilometers, and the dynamic range of detection range is very big.At this moment, general fixed frequency mechanical shutter certainly exists some measurements blind area, can not realize the continuous working of great dynamic range.
As shown in Figure 1, in order to guarantee that the light beam of certain diameter is realized break-make control, the blade that is in the light of mechanical shutter must have certain width.Like this, in the cycle, be in the light time respectively account for certain ratio between the logical light time at a shutter.Ratio on this time cycle can be with the ratio value representation of light-blocking region and the fan-shaped angle of transparent zone.If the fan-shaped angle of light-blocking region is φ 1, the fan-shaped angle of transparent zone is that the fan-shaped angle of 2, one shutter make and break periods of φ is (φ 1+ φ 2).As shown in Figure 1, the shutter transparent zone and the ratio in shutter cycle, promptly logical light dutycycle is:
η＝φ2/(φ1+φ2) (1)
Limited by the physical dimension of mechanical shutter, the logical light dutycycle that generally can realize is up to about 90%.
If the distance of the target range detector of laser radar is L, the light velocity is c, and pulse laser is transmitted into the time that turns back to detector on the target again from laser radar and is so:
t＝2L/c (2)
If the work repetition frequency of mechanical shutter is f, period of time T=1/f.Logical light dutycycle is η, and the time of being in the light in one-period so is (1-η) T.If the time of pulse laser return detector is just in time dropped on the zone of being in the light of mechanical shutter, this signal accent that just is blocked can not be received.The condition that this shutter blind area situation takes place is:
0＜(t-nT)＜(1-η) T, n=0 wherein, 1,2 ... integer (3)
The pass that can obtain effective detection range L and effective shutter frequency f and logical light dutycycle η from following formula is:
1/2 (n+1) c/f＞L＞1/2 (n+1-η) c/f, n=0 wherein, 1,2 ... integer (4)
Fig. 2 is when with laser radar a typical space target being observed, and target range is curve over time.If setting the frequency of operation of mechanical shutter is 500Hz, logical light dutycycle is 90%, can realize operate as normal to most of distances so, but in some distance, heliogram is blocked by blade, forms the shutter blind area, shown in the thickened portion among Fig. 2.Calculate according to following formula, the scope of blind area is: 900km-930km, 1200km-1230km, about 10 seconds of the duration of each shutter blind area.Very big difficulty will be brought to the lasting observation of target in this shutter blind area, if the logical light dutycycle of mechanical shutter is littler, perhaps frequency of operation is unreasonable, when the target that detection range is had great dynamic range change is carried out work, the shutter blind area to influence meeting more serious.
Fig. 3 is under 90% logical light dutycycle condition, the graph of a relation of the EFFECTIVE RANGE of mechanical shutter and shutter frequency.As seen from the figure, to each fixed frequency, must on some distance, there be shutter blind area (the breakpoint zone of ledgement is the shutter blind area among the figure).The position difference of the shutter blind area of different frequency.Along with the continuous variation shutter blind area of shutter frequency also in continuous variation.If the shutter frequency can change continuously along with detection range, might in a sizable detection range dynamic range, there be the shutter blind spots limit so.
Summary of the invention
Technology of the present invention is dealt with problems: overcome the deficiency that there is the blind area under to operating distance great dynamic range scene change in existing fixed frequency mechanical shutter, a kind of method for controlling frequency conversion of rotary disk mechanical shutter is provided, can under the scene of the big dynamic change of target range, realizes non-blind area work.
Technical solution of the present invention: the method for controlling frequency conversion in large dynamic range without blind area of rotary disk mechanical shutter, adopt the frequency conversion mode to work, the frequency of operation of mechanical shutter changes along with the variation of detection range, avoids the influence of mechanical shutter blind area to surveying, and performing step is:
(1) the logical light dutycycle η intrinsic according to rotary disk mechanical shutter, i.e. the transparent zone territory and the ratio in shutter cycle, and given detection range L are determined the scope that mechanical shutter can normal working frequency f, computing formula is:
1/2 (n+1) c/L＞f＞1/2 (n+1-η) c/L, n=0 wherein, 1,2 ... integer, c is the light velocity; (5)
As seen the frequency range that mechanical shutter can operate as normal is very wide, the control accuracy of mechanical shutter frequency is required very loose, realizes easily under the practical application condition;
(2) determine the optimum working frequency f of the mechanical shutter under certain detection range
Optimum, guarantee that operate as normal still takes place under certain disturbance change condition for frequency of operation at mechanical shutter, but optimal frequency be set at normal working frequency higher limit and lower limit in the formula 5 the intermediate frequency value of definite scope, computing formula is:
f
Optimum={ [1/2 (n+1) c/L]+[1/2 (n+1-η) c/L] }/2
=1/4 (2n+2-η) c/L, n=0 wherein, 1,2 ... integer, c is the light velocity (6)
According to formula (6) as can be known, along with detection range L becomes big continuously, the corresponding continuous reduction of optimum shutter frequency f; Otherwise L diminishes continuously along with detection range, the corresponding continuous rising of optimum shutter frequency f.So, can guarantee that rotary disk mechanical shutter can both non-blind area work to big distance range according to detection range real time altering shutter frequency of operation.
The present invention compared with prior art has following beneficial effect:
(1) frequency of operation of rotary disk mechanical shutter changes along with the variation of detection range, detection range blind area and the dynamic range restriction of effectively avoiding the fixed frequency mechanical shutter to bring, for application scenarios such as laser radars, can in very large range avoid the influence of mechanical shutter blind area after the work of employing variable frequency control mode, obtain enough big range sensing dynamic range.
(2) mechanical shutter conversion method of the present invention is very loose to the frequency setting accuracy requirement of mechanical shutter, realizes easily under the practical application condition.
Description of drawings
Fig. 1 is a quaterfoil rotary disk mechanical shutter structural representation, and the fan-shaped angle of light-blocking region is φ 1, and the fan-shaped angle of transparent zone is φ 2, the shutter transparent zone and the ratio in shutter cycle, and promptly logical light dutycycle is η=φ 2/ (φ 1+ φ 2);
Fig. 2 is during from ground observation, and the distance of a typical space track target is change curve in time.Tab area in the curve is under the 90% logical light dutycycle condition, the detection blind area that 500hz fixed frequency shutter produces;
Fig. 3 is under fast gate open light dutycycle 90% condition, the graph of a relation of the EFFECTIVE RANGE of mechanical shutter and shutter frequency, and wherein the breakpoint zone of ledgement is the shutter blind area.Different shutter frequencies has different shutter blind areas.Among the figure 1. 2. 3. 4. four curves be the variable frequency control scheme of four kinds of mechanical shutters that the extraterrestrial target track according to Fig. 2 can adopt;
Fig. 4 is the extraterrestrial target track according to Fig. 2, and under fast gate open light dutycycle 90% condition, the optimal frequency of four kinds of mechanical shutters that can adopt is with the change curve of orbit time.Among the figure 1. 2. 3. 4. four curves with Fig. 3 are corresponding, Integer n=1,2 in the corresponding formula 6 respectively, 3,4;
Fig. 5 is the extraterrestrial target track according to Fig. 2, and under fast gate open light dutycycle 90% condition, the optimal frequency of the mechanical shutter that can adopt and the upper and lower bound of effective frequency are with the change curve of orbit time.
Embodiment
In a laser radar system, need send pulse laser simultaneously and measure the laser signal that returns from target, obtain the information such as distance, light echo intensity of target.For the short range scattering that guarantees to send laser does not influence detection to the faint light of returning from target reflection, adopt rotary disk mechanical shutter that the sequential of emission laser and detectable signal is accurately controlled.The structure of rotary disk mechanical shutter as shown in Figure 1, four blades that are in the light that on circumference, evenly distribute, logical light dutycycle is 90%.
The distance that is illustrated in figure 2 as a typical space target is the forecast result of curve over time.According to the restrictive condition analyses such as motor speed of mechanical shutter, the maximum operation frequency of mechanical shutter is 600Hz.The frequency of operation of supposing mechanical shutter is fixed as 500Hz, can realize operate as normal to most of distances so, but in some distance, heliogram will be blocked by blade, forms the shutter blind area, shown in the thickened portion among Fig. 2.Because detection mission does not allow to interrupt, so can not adopt the fixed frequency control mode, need to adopt the method for controlling frequency conversion in large dynamic range without blind area of rotary disk mechanical shutter provided by the invention, the frequency of operation of rotary disk mechanical shutter is changed, detection range blind area and the dynamic range restriction of effectively avoiding the fixed frequency mechanical shutter to bring along with the variation of detection range.
The specific implementation step is:
(1) according to the logical light dutycycle η of rotary disk mechanical shutter, and under the given detection range L condition, determines the scope of the frequency f that mechanical shutter can operate as normal.Computing formula is:
1/2 (n+1) c/L＞f＞1/2 (n+1-η) c/L, n=0 wherein, 1,2 ... integer
(2) determine the optimum working frequency f of the mechanical shutter under the different detection ranges
OptimumBut optimal frequency is set at the intermediate frequency value of normal working frequency scope, guarantees that operate as normal still takes place under certain disturbance change condition for frequency of operation at mechanical shutter, and computing formula is:
f
Optimum=1/4 (2n+2-η) c/L, n=0 wherein, 1,2 ... integer
Fig. 4 is respectively when n=1,2,3, the optimum working frequency of mechanical shutter 4 time.Along with detection range is near by change far away, optimum shutter frequency is uprised by low; Along with detection range is far away by nearly change, optimum shutter frequency is by high step-down;
(3) selected according to actual needs a kind of mechanical shutter frequency conversion programme of work.If according to the restrictive condition analyses such as motor speed of mechanical shutter, the maximum operation frequency of mechanical shutter is 600Hz, so as can be known from Fig. 4 the 1st, 2 two kind of scheme meet the demands, and the 3rd, the frequency of 4 two kind of scheme is too high exceeds requirement.According to the task needs, the frequency of detection is fast more, the measurement data amount is the bigger the better, and determines that so finally the 2nd kind of mechanical shutter variable frequency control scheme among Fig. 4 meets the demands.
Fig. 5 is the change curve of the upper and lower bound of optimal frequency that mechanical shutter can operate as normal and effective frequency with orbit time.As seen adopt mechanical shutter conversion method of the present invention, it is accurate especially that the frequency setting of mechanical shutter is not required, can fluctuate in tens hertz bigger scope, and this is easy to realize with technological means such as frequency of phase locking controls under the practical application condition.
Claims (2)
1, the method for controlling frequency conversion in large dynamic range without blind area of rotary disk mechanical shutter is characterized in that the variation real time altering shutter frequency of operation according to detection range, and step is as follows:
(1) the logical light dutycycle η intrinsic according to rotary disk mechanical shutter, i.e. the transparent zone territory and the ratio in shutter cycle, and given detection range L are determined the scope that mechanical shutter can normal working frequency f, computing formula is:
1/2 (n+1) c/L＞f＞1/2 (n+1-η) c/L, n=0 wherein, 1,2 ... integer, c is the light velocity;
(2) determine when detection range L changes mechanical shutter optimum working frequency f
OptimumChanging Pattern, promptly when the detection range L of target changes, make mechanical shutter optimum working frequency f
OptimumVariation and detection range L be varied to inverse ratio, so according to detection range real time altering shutter frequency of operation, can guarantee that rotary disk mechanical shutter can both non-blind area work to big distance range.
2, the method for controlling frequency conversion in large dynamic range without blind area of 1 described rotary disk mechanical shutter as requested, it is characterized in that: described mechanical shutter optimum working frequency be set at normal working frequency higher limit and lower limit the intermediate frequency value of definite scope, computing formula is:
f
Optimum=1/4 (2n+2-η) c/L, n=0 wherein, 1,2 ... integer, c is the light velocity.
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| CNB2006101650873A CN100510929C (en) | 2006-12-13 | 2006-12-13 | Method for controlling frequency conversion in large dynamic range without blind area of rotary disk mechanical shutter |
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| CNB2006101650873A CN100510929C (en) | 2006-12-13 | 2006-12-13 | Method for controlling frequency conversion in large dynamic range without blind area of rotary disk mechanical shutter |
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| CN1963655A true CN1963655A (en) | 2007-05-16 |
| CN100510929C CN100510929C (en) | 2009-07-08 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102749786A (en) * | 2012-07-10 | 2012-10-24 | 中国科学院光电技术研究所 | Synchronous time sequence control method for turntable type mechanical shutter |
| CN110680354A (en) * | 2019-09-30 | 2020-01-14 | 中国人民解放军第四军医大学 | X-ray shutter control system and method, control device and application |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH469997A (en) * | 1967-06-27 | 1969-03-15 | Niezoldi & Kraemer Gmbh | Motion picture camera with adjustable wrap-around fastener |
| JP3553515B2 (en) * | 2001-03-16 | 2004-08-11 | 三菱重工業株式会社 | High precision ranging laser radar device |
| CN100359402C (en) * | 2003-07-16 | 2008-01-02 | 中国科学院光电技术研究所 | High repetition frequency high precision rotating disk type mechanical shutter device |
-
2006
- 2006-12-13 CN CNB2006101650873A patent/CN100510929C/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102749786A (en) * | 2012-07-10 | 2012-10-24 | 中国科学院光电技术研究所 | Synchronous time sequence control method for turntable type mechanical shutter |
| CN102749786B (en) * | 2012-07-10 | 2015-04-01 | 中国科学院光电技术研究所 | Synchronous time sequence control method for turntable type mechanical shutter |
| CN110680354A (en) * | 2019-09-30 | 2020-01-14 | 中国人民解放军第四军医大学 | X-ray shutter control system and method, control device and application |
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| CN100510929C (en) | 2009-07-08 |
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