CN1126853A - Control of laser light power output for use in light scattering instruments by inducing mode hopping and averaging results - Google Patents
Control of laser light power output for use in light scattering instruments by inducing mode hopping and averaging results Download PDFInfo
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- CN1126853A CN1126853A CN 95101046 CN95101046A CN1126853A CN 1126853 A CN1126853 A CN 1126853A CN 95101046 CN95101046 CN 95101046 CN 95101046 A CN95101046 A CN 95101046A CN 1126853 A CN1126853 A CN 1126853A
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Abstract
Some solid laser has compact structure and is suitable for installed in optical scattering instrument. However, mode skip always makes the output power of the said laser unstable. The present invention provides an ideal method and apparatus, by which it is possible to modulate laser driving current at the conditions of low freq and the amplitude sufficient to induce and control mode skip so as to measure accurately the ratio of optical scattering signal to output laser power.
Description
Owing to the present invention relates to the laser instrument that some kind of use is used for light scattering measurement, the following United States Patent (USP) relevant with these measurements quoted for your guidance by this paper: patent
#In 4,541,719 (on September 17th, 85), denomination of invention is " be used to characterize microscopic particle and measure their method and apparatus to the response of its surrounding medium "; Patent
#In 4,548,500 (on October 22nd, 85), denomination of invention is " device of the method for identification or sign fine particle "; Patent
#In 4,693,602 (on November 6th, 84), denomination of invention is " method and apparatus of measuring fine particle light scattering character "; Patent
#In 4,710,025 (on Dec 1st, 87), denomination of invention is " being used to characterize the method for fine particle suspension "; Patent
#In 4,907,884 (on March 13rd, 90), denomination of invention is " a sample monitoring system "; Patent
#In 5,129,723 (on July 14th, 92), denomination of invention is " the neat nurse chromatograph of high-performance "; Patent
#Des 329,821 (on February 21st, 89), denomination of invention is " device of measuring the fine particle in the liquid suspension with light scattering method ".
Carefully measure the only a kind of easy and general laboratory technique that molecule from solution and the fine particle from solution scatter, be used to measure their various physical features, being its molecular weight and size for molecule for example, is its size and structure for particle.If combine with various chromatographic separation devices and concentration detector, such light-scattering measurement can also be derived the differential distribution curve of this tittle.Relevant light scattering measurement, to their performance demands and the result's that may derive the comment of seeing the above Wy-att that quotes that studies in great detail.Because breadboard space is limited and expense is expensive,, the needs of compact design have been utilized the even more ideal minimum semiconductor diode laser source of bigger gas laser source so the design of compact device is favourable.Yet, semiconductor diode laser also exist some for be applied to light scattering apparatus and detecting device the problem that must solve.
In these problems, comprise owing to the mode hopping (abrupt change of the performance number of mode-hopping) occur.The little variation of laser instrument service condition is because main oscillations changes the operate power generation abrupt change that another kind of pattern can make laser instrument into by a kind of pattern.This effect can be produced by the minor variations of the light of temperature, drive current or reflection return laser light device.Catoptrical variation is the original part of light scattering measurement, because put into sample extra light is scattered and the return laser light device, and the solution variation of analysing the light rate has also changed the phase place of scattered light.Extra light can be reflected to the laser instrument from some positions that laser beam passes in and out sample cell.What prevent this scattering needs expensive additional member with light that reflects and laser instrument interaction.For complicated sample retaining member (for example at United States Patent (USP) 4,616, the flow cell described in 927) extremely, make that perpendicular to the massive parallel surface of incoming laser beam setting it almost is impossible fully phasing out retroreflective member.When temperature and drive current were in the critical point of mode conversion, some little random variation of catoptrical energy level and phase place just can cause the laser power a few percent that promptly fluctuates up and down.
Utilize light scattering apparatus, or more common be to utilize light scattering photometer, measured main physical character is the power that incides the light on the sample of unit area and the ratio of the power of the light of the sample scattering of unit sterad.If lasing light emitter is very stable, so, as correct operation, incident optical power only need be measured once.Unfortunately the power of laser instrument is tending towards changing with temperature, reflected light, drive current and time.The easy method of handling the laser power variation is exactly cutting out partial laser beam and the power of monitoring this laser instrument by a photodetector with this part laser beam.Laser monitoring signal of Chan Shenging or the power by providing feedback can be used for stablizing this laser instrument for the circuit of adjusting drive current perhaps can be used for making the scattered light signal standardization in the process of measured data being carried out mathematics manipulation like this.No matter which kind of situation, its effect all is to utilize laser monitoring signal segmentation scattered light signal.Yet these two kinds of methods still can produce little error.Lasing mode jumps and may take place very fastly, be directed at laser power and occur changing in the short time, up to monitor feedback signal and control circuit drive current can be adjusted to return to the power rating that meets the requirements till.To such an extent as to do not follow if signal changes the detection of too fast monitor, shortage instantaneity and signal averaging symmetry can cause tangible error equally in measuring scattered light signal and laser monitoring signal so.Another source of error be laser beam may comprise more than one skies the time with component or little laser beam (beamlet) time.This laser monitoring device may respond the different combination of these little laser beam and the light scattering detector that do not respond, like this, just make this monitor can not accurately follow the tracks of one with the proportional signal of scattered signal.Owing to all these reasons, unexpected, the normally high-frequency laser power variation of preferably avoiding these to cause owing to mode hopping.
In optics or signal of communication application, the mode hopping noise of diode laser presents high frequency and had become the theme of many research reports and some patents already.The noise of this very high frequency is especially troubling in communications applications, and this is because it appears at the much the same frequency of frequency with desirable signal of communication itself.Because light scattering measurement normally carries out under extremely low frequency, so only need average scattering detection signal and average detection signal are done accurate tracking.Utilize the 2.5GHz drive current to modulate to reduce in the list of references of J.Vanderwall that this content of high frequency mode popcorn noise drawn in front and J.Blackburn and reported.As quote the front, utilize 100MHz to do report with the noise that the driving of upper frequency modulation reduces in the video disk system by the slip-stick artist M.Ojima and the S.Yonezawa of Hitachi company, the slip-stick artist K.Stubkjaer of IBM Corporation and M.Small reports and use 50-200MHz to modulate the reduction noise.In addition, the works of Ojima that is quoted etc. has used the modulation under the frequency of 200MHz-1GHz.In the works of E.Gage that is quoted and S.Beckens, the best modulation driving frequency that is used to reduce high frequency noise relates to the time delay of the light of the return laser light device that is reflected.Once studied 100-450MHz modulation driving frequency.In addition, the modulation of high level was used in these researchs, in part modulation period, drive current accurately was controlled at below the threshold value, and probably also will cuts off relevant emission during this period.
Quoted license to Hitachi, invention people for Ryoichi Ito, be entitled as the United States Patent (USP) 3 of " method and apparatus that is used for directly modulated laser ", 815, in 045 (1974), described the situation of utilizing a drive current through ovennodulation to make the conversion between the different pattern of two spatial properties of a semiconductor laser, this has caused by only select in the spatial model one that outgoing laser beam is carried out high frequency modulated with optical means.This method can not be used for light scattering photometer, and reason is that light scattering photometer needs stable light beam, rather than modulated beam of light.The optimal laser instrument that is used for light scattering apparatus is according to a unique spatial model job, to guarantee a light beam through alignment.If will make the aggravation of parasitic light problem according to described other spatial model work of Ito.
(the invention people is M.K.hno and J.Itami for Japanese patent application SHO 59 9086 and its corresponding German patent application DE 41 33 772A1 (on May 21st, 1992), license to Mitsubishi company) describe a compact especially disk and read detector arrangement, according to this configuration, the noise that causes of reflected light has been reduced to greatest extent by the modulation under 500-600MHz frequency.The selection optimum frequency is the distance according to the echo area of lasing light emitter and this disk.It is because following reason that this principle is not suitable for light scattering apparatus: the first, and use the driving power of 500MHz uneconomical and inconvenient.The second and since the light scattering specimen material normally along or pass laser beam and carry by fluid stream, therefore, not have fixing scattering distance, so do not have single best high frequency modulated yet.The 3rd, the noise that reduces high frequency is unimportant in the light scattering apparatus that uses 0.1-10 seconds signal averagings usually.
Be important to note that in all prior arts the method that reduces noise all concentrates on laser output power itself, and does not directly utilize filtering, to the detected signal number of winning the confidence mean value or ask this signal and the digital ratio of laser monitoring value.Because we were concerned about is the combination property of overall optical scatterometer of power ratio that only needs to measure the incident laser of scattered light, so may allow, even encourage the fluctuation that laser instrument is exported, if this fluctuation can be followed the tracks of or can eliminate after input effectively.The way that we address this problem is mode hopping noise and the frequency that changes more than the passband of signal processing filter in this detection system.Like this, Laser Driven modulation, matched signal average filter, and the ratio of scattered light and incident light is whole pith of the present invention.
Fig. 1 shows the block scheme of antihunt means, and it has constituted the part of a light scattering detection system of the preferred embodiments of the present invention.
Fig. 2 A and 2B show the modulation of institute's making alive with the triangular wave drive current that is produced of laser drive current.
Fig. 3 A and 3B show the effect of the method for described reduction noise for the laser power mode hopping noise that is caused by temperature drift, and Fig. 3 C and 3D show the method for this reduction noise for the effect by the caused laser power mode hopping of the light noise that reflects from a light scattering sample.
Fig. 4 shows the circuit diagram at the exemplary apparatus of the power supply laser stabilization method of a solid-state InGaAIP laser instrument that is used for the 690nm wavelength, works under the 20mW peak power.
Task of the present invention is to allow the solid-state laser source of compactness is used for light scattering apparatus.Similar techniques also can be used to demonstrate the lasing light emitter of the other types of high-frequency fluctuation, and this common staff for this area is conspicuous.Traditional light scattering apparatus or photometer are at one or more measurement of angle scattered lights; and can use together with the light source with the non-constant output of slow variation, this is because they also utilize the density of beam splitter or other device monitoring incident light sources usually.Because the mode hopping that carries out the reflected light of laser instrument and/or the caused mode hopping of parasitic light again and cause by temperature variation, laser instrument, particularly density fluctuation or stepped fast may appear in the output of solid state diode lasers sometimes, and this variation can not the in addition average fully and monitoring by means of standard technique.For example, the variation of mode configuration can not only change total output power of laser instrument, but also can change laser instrument monitoring power and the ratio that incides the power on the sample.These problems are particularly serious for the faint micromolecular extremely rare solution of scattered light therein, and because parasitic light can change with the variation of zlasing mode, so will accurately deduct parasitic light.By adjusting laser intensity according to a kind of like this mode, make in the laser monitoring device and in light scattering detector, resulting signal can be effectively in addition filtering and can being measured accurately, the present invention proposes this viewpoint.By modulation, Laser Driven promptly scans all available mode configurations, and the stepped in average signal has just been eliminated.Then, just can be to the resulting ratio accurately of following the tracks of and can measure scattered light and incident light accurately that changes slowly.Often have in the laser instrument of outer lens at some, the modulation format that can use other to be changing mode configuration, for example mobile laser cavity reflective mirror or carry out the optical phase modulation in laser cavity.
Like this, the present invention has just reduced the influence of mode hopping to tested light scattering ratio.The present invention also forms contrast with the prior art of attempting the optical signalling that stable laser itself produces, even contain power swing rapidly through the modulated laser output packet, to the electronics mean effort of the laser instrument modulated output also can eliminate the acute variation of power level and only keep average laser power little, slowly, level and smooth variation.This average laser power level of drift slowly utilizes one to separate the measurement of laser beam monitor.Light scattering signal is can be similarly in addition average, producing a kind of signal level and smooth, that slowly change, and the result, light scattering measurement if desired just can be measured the scattered light signal of monitoring at each angle ratio with respect to laser power signal.
Fig. 1 shows the structure of the light scattering measurement that carries out in a light scattering photometer, this measurement has used a kind of fluid by the sample cell 1 that is wound with a series of light scattering detectors 2 through overcorrect around the figure to flow.Described light scattering detector and the following detecting device that is used to monitor radiation source/laser instrument that will mention generally are the hybrid optical electric diodes that linear amplifier is often arranged.From in history, photomultiplier is used for this purpose always, although the red wavelength quantitative effect that they are launched at the laser diode of many types is very poor.Sample shines with a solid-state laser 3, and the controlled current flow power supply 4 of this laser instrument is subjected to the modulation of a wave producer 5.The general combination of described solid-state laser has optical alignment's lens devices, result, this laser instrument will produce the output through alignment, is commonly referred to as light beam 10.In a preferred embodiment of the present invention, described wave producer produces a triangular wave.Sample cell can have and is similar at United States Patent (USP) 4, although the design in the sort of pond described in 616,927 is the pond of other type, for example, be subjected to the irradiation of solid-state laser rectangle or columnar pond also can be used to make photometer with same laser modulation method.Each all has the amplifier that comprises analog filter 6 independent light scattering detector.The signal of Chan Shenging is by an independent digital quantizer/comprise that digital filter carries out digitized processing like this, to eliminate the signal with the inconsistent upper frequency of experiment condition to be measured.The wave filter with numeral of simulation generally is those frequencies that produce by laser instrument is modulated in order to stop, can make the low-pass filter of general frequency by selecting of light scattering signal to be measured simultaneously again.Certainly, the signal that also can use an analog multiplexer will carry out signal imitation switches to digital quantizer, to obtain same net result.Just can carry out multipath conversion through the digitized signal of handling like this, so that be transferred to computing machine 9 by the series connection end of described computing machine with a digitizing traffic pilot.The part of laser beam 10 enters a laser monitoring device 12 that has to its combined similar electron device 6 and 7 by a beam splitter 11 guiding.
Because the laser diode drive current is an important parameter that is used to control laser power and prevents to damage laser diode,, certainly, also can use Norton equivalent voltage source and current-limiting resistor so the Current Regulation power supply is usually used in conventional design.The modulated laser electric current and like this to one of available mode state " sampling " easily method be exactly that the voltage with waveform of cycle variation is added on the reference voltage of power supply, the result, laser diode current just changes with periodic waveform.Preferably adopt triangular waveform, this is in each levels of current (Cur-rent Level) spending same time because of triangular waveform, although also can use other waveform, in this preferred embodiment, utilize signal controlling that peak point current is limited to a value to laser diode safety, and a kind of independently control allows the degree of modulation is regulated.For mode hopping noise filtering the most at last gets ideally, can be adjusted the degree of depth of modulation.The minimum drive current that emission laser begins to occur is called as threshold current.When drive current rises to threshold level when above, laser output is risen rapidly.We have found that actually, and the peak-peak value modulation that is higher than the electric current of threshold value 15% generally is exactly to obtain the effect of filtering noise, yet to work although current value is higher than threshold value 50% most.For example, have the diode of 40mA,, need the one peak value modulation of 0.15 * (60-40)=3mA peak, so that obtain final filter effect if under 60mA, work.Maximum laser diode drive current is defined the instantaneous peak value that makes laser instrument generation permanent damage less than a meeting.In fact, laser instrument can use very and come work near this instantaneous peaked average current.Therefore, any modulating mode all can relate under lower drive current will spend the regular hour, and causes lower average output power.The advantage of this preferred embodiment of the present invention is only to need 15% modulation, only loses few average power output because do like this.Best modulating frequency depends on that system on certain program.For example, for the concrete photometer structure of the commercially available mini DAWN system InGaAlP laser instrument that a 20mW is housed (for example at the 690nm wavelength by the TOLD9140 of the Toshiba type of single translative mode work), that make by Wyatt Technology Corporation, we find modulating frequency be 150Hz be suit and effectively.This frequency is enough high so that utilize mould one wavenumber filter of this instrument to be able to effective filtering, and low being enough to effectively the sampling of jumping of this vertical pattern.Theoretically, this modulating frequency should be bigger 10 to 1000 times than the frequency of measured scattered light signal.The Laser Output Beam that is used for the light scattering letter generally is that the polarization of even now is not main for the present invention through linearly polarized.In a preferred embodiment of the present invention, when carrying out light scattering measurement, incident light should vertical polarization (with respect to the surface level that contains light scattering detector).
Fig. 2 A and 2B show respectively and are the employed impressed voltage of output power of this laser instrument of modulation and the laser drive current that is produced in a preferred embodiment of the invention.The order of magnitude that flows into the survey frequency of the typical light scattering signal that is produced in the process of optics flow cell of a light scattering detector at a duplicate samples eluant is several Hz or littler.In view of the above, we find that the order of magnitude is that the modulating frequency of 150Hz is suitable for the scrambling of filtering fully by the laser power of mode hopping generation.Measure the situation of the scattered signal of upper frequency at needs, should correspondingly improve the Laser Modulation frequency.As previously mentioned, thumb rule points out that selected modulating frequency should be than detecting big 1 to 3 order of magnitude of frequency.Separate the typical light scattering measurement that carries out for the liquid chromatography with polymer samples, 50 to 500Hz frequency is enough.We find that every type laser instrument/detection architecture form may need different optimum frequencies and laser diode current modulation amplitude.After following these examples that provide, the those of ordinary skill in light scattering apparatus field judges that the optimum modulation frequency of the lasing light emitter of most of types (their mode hopping is induced the light scattering measurement of noise effect back) and amplitude will be the suitable nothing the matters of part.Although most preferred embodiment of the present invention has comprised the triangular modulation in laser current source, can gratifying other forms are conspicuous for those of ordinary skills.These forms comprise the periodic or random waveform that simple sine wave, sawtooth involve can scanning of any other and whereby all expections sampled for the influential all patterns of output-power fluctuation.
Fig. 3 A-3D shows the collected experimental data of triangular modulation of utilizing preferred embodiment.The data presentation of the mark 13 of Fig. 3 A goes out by with a heating shower nozzle transient heating diode laser, then make laser power output of the non-modulated that its cooling produced.Use 15%, after the 150Hz modulated triangular wave shape laser current, obtained the result 14 of Fig. 3 B.Should note.Long variation level and smooth in the laser power is unimportant for typical light scattering measurement, and this is because by being standardized divided by light beam monitor signal scattered signal.Finish such standardization normally by by analog-digital converter make each SIMULATED SCATTERING signal and laser monitoring is signal digitalized, use a digital signal processor filtering to digital data, such value through digitizing and Filtering Processing is deposited in the computer equipment.Then with each digitized like this scattered light signal divided by digitized laser monitoring signal, obtain the digitizing ratio of each scattered light signal whereby, calculate needed ratio like this.In other words, described signal ratio through filtering can utilize analog divider to produce, and by means of this analog divider, this output ratio signal itself also is an analogue value.Say for this area ordinary skill, other versions of this total method also can occur, for example use laser monitoring Signal Regulation average laser power.When a close-boiling cut polystyrene sample being injected when flowing through the solvent of photometer system shown in Figure 1, obtained shown in Fig. 3 C produced do not add 90 of modulation.Scattered light signal 15 also obtains the corresponding output laser power 16 shown in Fig. 3 C simultaneously.The noise of noting 17 places, peak of Fig. 3 C is the return laser light device causes because scattered light is reflected mode hopping formation.Utilize Laser Modulation, with digital 18 marks, laser power is with digital 19 marks in Fig. 3 D for corresponding average scattering signal.Peak-data 20 shown in Fig. 3 D does not demonstrate the scrambling of the peak-data shown in Fig. 3 C17.The light scattering signal of the laser current of attention non-modulated is by influencing laser power output itself with some light scattering return laser light device and/or by changing catoptrical phase place.
Fig. 4 shows the synoptic diagram of preferred embodiment that a width of cloth is supplied with a circuit of the laser diode modulating current be used for the described light scattering photometer of Fig. 1.Pot 21 is transferred to the control panel of a field effect transistor 28 of this operational amplifier of noninverting input control of an operational amplifier with an adjustable dc voltage, and this field effect transistor is controlled the electric current of transporting to laser diode 29 again.The negative feedback of supplying electric current control operational amplifier is to be provided by the voltage of striding resistors in series 27 generations.Modulation produces by a square-wave voltage 22 is ac-coupled in the Current Control output by coupling condenser 23 and adjustable repeating resistance device 24.The wave filter effect of resistor 24 and integrating condenser 25 is converted into the desired triangular wave that better approaches with the rectangle input.The AC coupling of modulation makes and can utilize the potentiometer 21 independent average DC laser currents of control and can utilize resistor 24 control modulation amplitudes.
Now, although we had discussed already and have been used to make the lasing light emitter that had noise originally can be used for light scattering apparatus effectively and survey those the preferred measures put device, but following content also is conspicuous for the ordinary skill of this area, Here it is also has a large amount of possible variations for the preferred embodiment of the present invention that we had illustrated already, and those conspicuous variations of modulation format, amplitude and frequency aspect all are included in the scope to greatest extent of the present invention.
Claims (26)
1. the method for the lasing light emitter of the intrinsic noise that produces owing to the mode hopping instability of control is used for light scattering measurement, comprises the steps:
A) than the survey frequency of scattered light signal larger about a frequency of 10-1000 times under and according to a amplitude peak laser drive current is modulated less than the peak current level of this laser instrument;
B) laser output beam that will so produce is isolated a part and is detected described separating part light beam so that obtain the corresponding measured value of described output beam power whereby with a photosensitive monitoring detecting device;
C) the signal averaging filtrator that uses a power swing that produces owing to described modulation as elimination to select is averaged to the signal that is produced by described monitoring detecting device;
D) according to one or multi-angle detect the laser beam irradiation that is subjected to described modulation the scattering of sample institute light and with a signal averaging wave filter that roughly is equivalent to the signal averaging wave filter selected for the described power swing of the described monitoring detecting device of elimination to each described detected scattered light signal being averaged by each described angle, the fluctuation of the scattered light that is detected that each described signal averaging fluid strainer elimination occurs owing to the modulation to described irradiating laser.
E) scattered light signal that will cross through so-called smoothing processing is divided by the laser monitoring signal of crossing through similar smoothing processing, so that obtain by the light of described sample scattering and the output ratio that is incident on the light on the sample for each of measured described angle.
2. method according to claim 1, the minimum amplitude that it is characterized in that described modulated laser drive current is greater than for suppressing the needed threshold drive current of Laser emission.
3. method according to claim 1 is characterized in that the peak-peak modulation of described laser drive current modulator is approximately higher than threshold value 15% greatly
4. method according to claim 1 is characterized in that described laser drive current modulation is about 150Hz.
5. method according to claim 1 is characterized in that described lasing light emitter is a solid-state laser diode.
6. method according to claim 1 is characterized in that described modulation is between 50-5000Hz.
7. method according to claim 1 is characterized in that described tested laser monitoring signal and scattered light signal have passed through digitized processing and described output than calculating with computer equipment.
8. method according to claim 1 is characterized in that described output than being to utilize each simulation division divided by described laser monitoring signal of described scattered light signal to obtain.
9. method according to claim 1 is characterized in that described laser drive current utilizes triangular waveform to modulate.
10. method according to claim 1 is characterized in that the peak of described Laser Driven modulator---the peak modulation is not more than 50% of threshold current.
11. method according to claim 1 is characterized in that the logical frequency of band of the scattered light signal that the modulation frequency ratio of described Laser Driven modulator is measured is big 10-1000 times.
12. method according to claim 1 is characterized in that described laser output beam is through the linear polarization processing.
13. method according to claim 5 is characterized in that described laser instrument is to operate on the wavelength of about 690nm.
14. method according to claim 1 is characterized in that described detecting device is a photodiode.
15. an irradiation system that is used for light scattering apparatus has a lasing light emitter that produces collimated light beam, this lasing light emitter is useful on the intrinsic noise that the instability owing to mode hopping occurs, and comprises with the lower part:
A) laser aid of the instable collimated light beam of the generation described mode hopping of described easy appearance;
B) can be under the frequency about 10-1000 times and by amplitude peak modulated laser drive current less than the peak current level of described laser instrument greater than the frequency of preparing to be used to measure scattered light signal;
C) be used for the described collimation laser output beam that produces is like this isolated one one device and is used to utilize a photosensitive monitoring detector means to detect described separating part, produce the device of the monitor signal that characterizes described output beam power whereby;
D) be used for filtering because described collimation laser device output beam is modulated and the monitor signal average filter device of the fluctuation that causes at described monitor signal, described signal averaging filter roughly is equivalent to be used for the signal averaging wave filter of described light scattering apparatus.
16. irradiation system according to claim 15 is characterized in that described modulating device produces one greater than the minimum laser drive current that suppresses the required threshold drive current of Laser emission.
17., it is characterized in that described modulating device produces a kind of peak to described laser drive current according to this irradiation system of claim 15---the peak modulation approximately is to be higher than threshold value 15%.
18. irradiation system according to claim 15, it is characterized in that described monitor signal average filter device comprises the mould-analog-to-digital conversion apparatus that is used to change described monitor signal, be used to store through the signal of such digitizing conversion and be used to handle and average described stored, through the digitized signal treating apparatus of the signal of digitizing conversion.
19. irradiation system according to claim 15 is characterized in that described laser aid is a solid state diode lasers.
20. irradiation system according to claim 15 is characterized in that described modulating device uses the described laser drive current of frequency modulation (PFM) of 50-5000Hz.
21. irradiation system according to claim 15 is characterized in that described photosensitive monitoring detecting device is a photodiode.
22. irradiation system according to claim 15 is characterized in that described laser drive current modulating device modulates described laser drive current to produce triangular waveform.
23. irradiation unit according to claim 15 is characterized in that the amplitude of the peak-peak modulation of described Laser Driven modulator is not more than 50% of threshold current.
24. irradiation unit according to claim 15 is characterized in that the logical frequency of band of the scattered light signal that the modulation frequency ratio of described Laser Driven modulator is measured is big 10-1000 times.
25. irradiation unit according to claim 15 is characterized in that described laser instrument produces a linear polarization output beam.
26. irradiation system according to claim 19 is characterized in that described laser instrument is in the wavelength work of about 690nm.
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| CN103235629A (en) * | 2012-03-30 | 2013-08-07 | 上海拜安实业有限公司 | Circuit structure capable of realizing automatic regulation and control of output power and corresponding method |
| CN103326777A (en) * | 2012-03-23 | 2013-09-25 | 富士通株式会社 | Optical power monitor, optical power control system and optical power monitor method |
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1995
- 1995-01-09 CN CN 95101046 patent/CN1097761C/en not_active Expired - Lifetime
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| CN103326777A (en) * | 2012-03-23 | 2013-09-25 | 富士通株式会社 | Optical power monitor, optical power control system and optical power monitor method |
| CN103326777B (en) * | 2012-03-23 | 2015-12-23 | 富士通株式会社 | Optical power monitor, optical power control system and optical power monitoring method |
| CN103235629A (en) * | 2012-03-30 | 2013-08-07 | 上海拜安实业有限公司 | Circuit structure capable of realizing automatic regulation and control of output power and corresponding method |
| CN103235629B (en) * | 2012-03-30 | 2014-12-17 | 上海拜安实业有限公司 | Circuit structure capable of realizing automatic regulation and control of output power and corresponding method |
| CN103018208A (en) * | 2012-12-07 | 2013-04-03 | 清华大学深圳研究生院 | Optical scanning scatterometer |
| CN103018208B (en) * | 2012-12-07 | 2016-04-20 | 清华大学深圳研究生院 | A kind of photoscanning scatterometer |
| CN109682732A (en) * | 2019-02-15 | 2019-04-26 | 华南理工大学 | Underwater hovering object concentration multi-angle combination measurement method and device |
| CN109682732B (en) * | 2019-02-15 | 2023-11-17 | 华南理工大学 | Multi-angle combined measurement method and device for concentration of underwater suspended matters |
| CN112217575A (en) * | 2019-07-12 | 2021-01-12 | 科大国盾量子技术股份有限公司 | Method and system for calibrating light intensity ratio of decoy state optical signal and signal state optical signal |
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| CN1097761C (en) | 2003-01-01 |
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