CN205192936U - Double -light -path polarimeter - Google Patents
Double -light -path polarimeter Download PDFInfo
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- CN205192936U CN205192936U CN201520915418.5U CN201520915418U CN205192936U CN 205192936 U CN205192936 U CN 205192936U CN 201520915418 U CN201520915418 U CN 201520915418U CN 205192936 U CN205192936 U CN 205192936U
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Abstract
The utility model relates to a double -light -path polarimeter, including light path subtotal circuit part, but the light beam that frequency modulation semiconductor laser sent loops through the polarizer, divide into two light beams behind the polarization splitting prism that disappears, depolarisation speculum, light beam passes through the sample cell, the analyser gets into photoelectric converter, another light beam passes through depolarisation speculum, analyser and gets into photoelectric converter, but the high frequency signal load that signal generating circuit produced to the frequency modulation semiconductor laser, signals drive step motor, step motor drives polarizer rotation, the signal of telecommunication loops through behind preamplification circuit, frequency -selecting circuit, envelope detection circuit, the amplitude limiting clamp circuit AD conversion unit among the input microprocessor unit, through the analog signal of conversion with the data signal form output storage at microprocessor data memory cell, export envelope detection circuit 4 after the data signal of microprocessor envelope detection circuit 1 unit in to envelope detection circuit 2 handles. Can be accurate find out optics zero point, improve the measurement accuracy of polarimeter.
Description
Technical field
The utility model relates to a kind of detection polarimeter, particularly a kind of laser frequency-modulation double light path polarimeter based on centroid algorithm and measuring method.
Background technology
When linearly polarized light is by some optically active compound or its solution, the phenomenon that its vibration plane can deflect around optical axis is called optical rotation phenomenon, and the angle of rotation is called optical activity.Polarimetry analysis (abbreviation polarimetry) utilizes linearly polarized light, causes optical rotation phenomenon by when the solution containing chemically reactive substance or liquid, and the plane of oscillation of the polarized light passed through is rotated to the left or to the right.Therefore, under certain conditions, the direction utilizing detection line polarized light to be rotated by Cucumber after vibration face and the number of degrees analyze the optical activity of some compound, or the impurity of detection compound, purity and content.For measuring the instrument of optical activity, be called as polarimeter.Polarimetry is used for measuring sugared concentration, and in recent years, polarimetry also applies to the fields such as pharmacy, food processing, chemical industry and biochemical analysis gradually.
According to Biot laws, the size of the optical activity of material is relevant with the wavelength of the temperature of material and linearly polarized light.The optical activity of some material increases with the rising of temperature, as quartz etc.But reduce with the rising of temperature as materials such as sucrose.In addition, the wavelength of linearly polarized light is different, and corresponding optical activity is also different.
The optical activity a (angle that linearly polarized light turns over along the direction of propagation through material after vibration face) of optically-active matter is directly proportional to the solution length 1 that optical active substance liquor capacity percent concentration c and polarized light pass through, a=kcl (1), wherein c is g/100ml, and 1 is mm.
The structural principle schematic diagram of traditional polarimeter as shown in Figure 1, sodium lamp is adopted to be light source 1, through aperture 2, object lens 3, a branch of comparatively simple directional light can be obtained as shown in Figure 1 after optical filter 4, directional light becomes linearly polarized light after the polarizer (I) 5, its plane of oscillation is 00 as Fig. 2 (a), when polarized light is through faraday's coil 6, due to magnetic opticity, the plane of oscillation of linearly polarized light is made to produce the β angle reciprocally swinging of 50Hz as Fig. 2 (b), light projects on photoelectric commutator 9 through analyzer (II) 8, produce the electric signal of alternation, when the polarized light vibration plane rotation alpha after the sample hose 7 by being equipped with sample
1degree is as Fig. 2 (c), and after instrument registration balance, the polarizer 5 oppositely turns over α
1degree compensate for the optical activity of sample, and as Fig. 2 (d), the signal that photoelectric commutator 9 receives, by being exported by frequency-selecting amplifier 12, power amplifier 13 after prime amplifier 10, automatic high pressure circuit 11, drives servomotor 14 again.
Fig. 3 is the curve synoptic diagram of faraday's coil working principle in prior art, and as shown in Figure 3, when instrument is orthogonal using two polariscope 5,8 optical axises, (OO ⊥ PP) is as optics zero point, does not put into optical active substance, now α=0o in sample hose.It is the β angular oscillation (Fig. 3 (a)) of 50Hz that faraday's coil 6 produces with frequency, obtains the electric signal (Fig. 3 (d)) of 100Hz, when being placed with α in sample hose at photoelectric commutator
1degree or α
2during the sample of spending, photoelectric commutator obtains the electric signal (Fig. 3 (b), (c)) of 50Hz, but their phase place just in time contrary (Fig. 3 (e), Fig. 3 (f)).Therefore, can make frequency of operation be 50Hz servomotor rotate.Polariscope 5 is turned over α (α=α by worm and gear 15 by servomotor 14
1or α=α
2), optics zero point got back to by instrument, and servomotor 14, under the control of 100Hz signal, reappears balance instruction.
To sum up telling, the method for this survey optical activity adopts faraday's coil modulated light signal, but the operating voltage of faraday's coil is high, and power consumption is large, and volume is large, and modulating frequency is 50Hz, and frequency is low, is subject to Hz noise, has a strong impact on measuring accuracy.The light source adopted in the method is in addition sodium lamp, and power consumption is comparatively large, easily aging.
Summary of the invention
The utility model is large for traditional polarimeter power consumption, that measuring accuracy is vulnerable to interference problem, propose a kind of double light path polarimeter, complete identical optical activity with traditional polarimeter to measure, but utilize light splitting to form bifocal path structure, eliminate the impact of the instability of light source, realize the function that instrument returns to zero in real time, realize Full-automatic digital and control, greatly reduce error, improve precision.
The technical solution of the utility model is: a kind of double light path polarimeter, comprise light path part and circuit part, described light path part is made up of Frequency Adjustable semiconductor laser, the polarizer, depolarization Amici prism, depolarized reflector, sample hose, analyzer and photoelectric commutator, the light beam that described Frequency Adjustable semiconductor laser sends successively by being divided into two light beams after the polarizer, depolarization Amici prism, depolarized reflector, a light beam enters photoelectric commutator by sample hose, analyzer; Another light beam enters photoelectric commutator by depolarized reflector, analyzer, photoelectric commutator connecting circuit part, circuit part is made up of signal generating circuit, pre-amplification circuit, frequency selection circuit, envelope detection circuit, amplitude limit clamping circuit, microprocessor unit and stepper motor; Microprocessor unit comprises microprocessor AD conversion unit, microprocessor data storage unit, microprocessor data processing unit, microprocessor digital display unit; The high-frequency signal that described signal generating circuit produces is loaded on Frequency Adjustable semiconductor laser, and sends drive singal to stepper motor, and stepper motor connects the polarizer, rotates for driving the polarizer; The electric signal of described opto-electronic conversion is successively by exporting the AD conversion unit in microprocessor unit to after pre-amplification circuit, frequency selection circuit, envelope detection circuit, amplitude limit clamping circuit, simulating signal through conversion is stored in microprocessor data storage unit with the output of the form of digital signal, and consequential signal is outputted to digital display unit after processing the digital signal in storage unit by microprocessor data processing unit.
The beneficial effects of the utility model are: double light path polarimeter of the present utility model, and application depolarization Amici prism builds bifocal path structure, can eliminate the impact that flashing is fixed, realize the function of zeroing in real time, complete the measurement of optically-active angle, there is volume little, the features such as cost is low, low in energy consumption; Use centroid algorithm, realize Full-automatic digital, greatly improve measuring accuracy.
Accompanying drawing explanation
Fig. 1 is the structural principle schematic diagram of prior art polarimeter;
Fig. 2 is the Vibration Condition of prior art polarized light
Fig. 3 is the curve synoptic diagram of prior art faraday coil working principle;
Fig. 4 is double light path Malus law curve synoptic diagram;
Fig. 5 is the theory diagram of double light path polarimeter of the present utility model.
Embodiment
As shown in Figure 5, a kind of double light path polarimeter, comprise light path part and circuit part, light path part comprises Frequency Adjustable semiconductor laser light resource 21, the polarizer 22, depolarization Amici prism 23, depolarized reflector 24, sample hose 25 and bigbore analyzer 26 successively.The light beam that Frequency Adjustable semiconductor laser 21 sends is successively by being divided into two bundles, a branch ofly entering photoelectric commutator A27 by sample hose 25, analyzer 26 after the polarizer 22, depolarization Amici prism 23, depolarized reflector 24; Another bundle enters photoelectric commutator B28 by depolarized reflector 24, analyzer 26, and circuit part comprises and is followed successively by photoelectric commutator A27 and photoelectric commutator B28, pre-amplification circuit 29, frequency selection circuit 30, envelope detection circuit 31, amplitude limit clamping circuit 32, microprocessor unit 33, stepper motor 44, signal generating circuit 35.Microprocessor unit 33 comprises microprocessor AD conversion unit, microprocessor data storage unit, microprocessor data processing unit; The high-frequency signal that signal generating circuit 35 produces is loaded on Frequency Adjustable semiconductor laser 21, and send drive singal to stepper motor 34, stepper motor 34 connects the polarizer 22 simultaneously, drives the polarizer 22 to rotate; The electric signal of opto-electronic conversion is successively by being input to the microprocessor AD conversion unit in microprocessor unit 33 after pre-amplification circuit 29, frequency selection circuit 30, envelope detection circuit 31, amplitude limit clamping circuit 32, after simulating signal is converted to digital signal by microprocessor AD conversion unit, be stored into microprocessor data storage unit, after microprocessor data processing unit processes the signal that storage unit stores, result outputted to digital display unit display.
Select Frequency Adjustable semiconductor laser 21 to substitute sodium vapor lamp light source, signal generating circuit 35 produces the square-wave signal of high frequency f, and be loaded on Frequency Adjustable semiconductor laser 21, laser output power is adjustable.Frequency is that the light of f is after the polarizer 22, become linearly polarized light, linearly polarized light is divided into two-beam after depolarization Amici prism 23, light beam is direct incident bigbore analyzer 26 after depolarized reflector 24, another light beam rotates after the optical active substance in sample hose 25, then through bigbore analyzer 26.Two bundle polarized lights are received by photoelectric commutator A27 and photoelectric commutator B28 respectively through bigbore analyzer 26.The frequency of linearly polarized light after determinand and analyzer 26 is constant, so it is f electric signal that photoelectric commutator A27 and photoelectric commutator B28 changes the light signal that two bundle frequencies are f into two class frequencys respectively, two groups of electric signal parallel input pre-amplification circuit 29 respectively, pre-amplifier unit 29 is for amplifying the electric signal inputted from photoelectric commutator A27 and photoelectric commutator B28, amplification signal is to drive frequency selection circuit 30, frequency selection circuit 30 is the signal of f and the signal of other frequency of filtering for selecting frequency, removes noise.Signal is by being input to microprocessor unit 33 after envelope detection circuit 31, amplitude limit clamping circuit 32, microprocessor AD conversion unit is used for being converted to digital signal by from amplitude limit clamping circuit 32 simulating signal out, and by two groups of signals under microprocessor digital unit records.Then signal generating circuit 35 sends signal Driving Stepping Motor 34 and drives the polarizer 22 to rotate.Stepper motor 34 often turns and moves a step, two class frequencys are that the polarization angle of the light signal of f just changes with the angle of the polarizer 22, the amplitude size of the light signal through bigbore analyzer 26 is caused to change, after opto-electronic conversion, enlarge leadingly, frequency-selecting amplification, analog to digital conversion, by the live signal of two-beam under microprocessor data unit records, point two groups of data storings.After stepper motor 34 turns over a circle, microprocessor carries out data processing to record two groups of signals, first the decomposition of FFT fast Fourier is carried out, and then by digital filtering, it is the amplitude of f signal and the curve of stepper motor rotational angle that the method finally by envelope detection obtains two about frequency.According to Malus law I=I
0cos
2α, this curve theory should be two curves as shown in Figure 4.And utilize centroid algorithm, calculate angle value corresponding to optics zero point on two curves respectively.Two angle differences are the angle of rotation of material.Again by data processing unit by this angle and known international standard comparison, calculate this solution concentration.Finally by numerical monitor Output rusults.
Utilize signal generating circuit to produce high-frequency signal to modulate light signal, object, in order to obtain the very high modulation signal of frequency, avoids Hz noise.In traditional polarimeter, servomotor is adopted to drive analyzer to be automatically rotated to optical null principle, and in the utility model, signal generating circuit produces signal Driving Stepping Motor 14 and drives the polarizer 2 to rotate a circle, by microprocessor, recorded two groups of signal datas are processed again, obtain two curves about light intensity and stepper motor rotational angle, recycling centroid algorithm, calculates the optical activity of material from curve.Utilize the utility model to calculate angle of rotation, compare conventional art, the impacts such as motor hysterisis error can be eliminated, find out optics zero point accurately, greatly improve the precision of polarimeter.And, adopt depolarization Amici prism 4 to form bifocal path structure in the utility model, eliminate the impact that flashing is fixed, realize real-time zeroing function, effectively prevent the Zero drift in main amplifier because the aging action such as light source or instrument and equipment causes, greatly improve measuring accuracy.
Measure the measuring method of optical active substance angle of rotation, its step is as follows: 1) regulate optical-circuit balance, make the polarizer 22 and bigbore analyzer 26 orthogonal and fixing; 2) after sample hose 25 adds optical active substance, light forms double light path by described light path part, article two, light path arrives photoelectric commutator A27 and photoelectric commutator B28 respectively through bigbore analyzer 26, and from two photoelectric commutators outputs are two high frequency ac signals; 3) AD conversion unit of two groups of AC signal input microprocessor unit 33 after the frequency-selecting of the amplification of pre-amplification circuit 29, frequency selection circuit 30, envelope detection 31, amplitude limit clamper 32, input microprocessor data storage cell after analog to digital conversion.4) stepper motor 34 drives the polarizer 22 to rotate, and the AC signal intensity of photoelectric commutator changes, each signal under microprocessor records.Obtain two curves by FFT and envelope detection, finally utilize centroid algorithm to calculate the optics zero point of two curves, difference obtains angle of rotation and then learns solution concentration.
Claims (1)
1. a double light path polarimeter, comprise light path part and circuit part, it is characterized in that: described light path part is by Frequency Adjustable semiconductor laser (21), the polarizer (22), depolarization Amici prism (23), depolarized reflector (24), sample hose (25), analyzer (26) and photoelectric commutator composition, the light beam that described Frequency Adjustable semiconductor laser (21) sends is successively by the polarizer (22), depolarization Amici prism (23), two light beams are divided into after depolarized reflector (24), article one, light beam is by sample hose (25), analyzer (26) enters photoelectric commutator, another light beam enters photoelectric commutator by depolarized reflector (24), analyzer (26), photoelectric commutator connecting circuit part, circuit part is made up of signal generating circuit (35), pre-amplification circuit (29), frequency selection circuit (30), envelope detection circuit (31), amplitude limit clamping circuit (32), microprocessor unit (33) and stepper motor (34), microprocessor unit (33) comprises microprocessor AD conversion unit, microprocessor data storage unit, microprocessor data processing unit, microprocessor digital display unit, the high-frequency signal that described signal generating circuit (35) produces is loaded on Frequency Adjustable semiconductor laser (21), and send drive singal to stepper motor (34), stepper motor (34) connects the polarizer (22), rotates for driving the polarizer (22), the electric signal of described opto-electronic conversion is successively by inputing to the microprocessor AD conversion unit in microprocessor unit (33) after pre-amplification circuit (29), frequency selection circuit (30), envelope detection circuit (31), amplitude limit clamping circuit (32), simulating signal through conversion is stored in microprocessor data storage unit with the output of the form of digital signal, and consequential signal is outputted to digital display unit after processing the digital signal in storage unit by microprocessor data processing unit.
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| CN201520915418.5U CN205192936U (en) | 2015-11-17 | 2015-11-17 | Double -light -path polarimeter |
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| CN201520915418.5U CN205192936U (en) | 2015-11-17 | 2015-11-17 | Double -light -path polarimeter |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108181858A (en) * | 2018-01-31 | 2018-06-19 | 中国地质大学（武汉） | A kind of collection of simulant signal and storage device |
| CN113253540A (en) * | 2021-04-25 | 2021-08-13 | 龙广秋 | Digital-analog converter for optical fiber communication |
-
2015
- 2015-11-17 CN CN201520915418.5U patent/CN205192936U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108181858A (en) * | 2018-01-31 | 2018-06-19 | 中国地质大学（武汉） | A kind of collection of simulant signal and storage device |
| CN113253540A (en) * | 2021-04-25 | 2021-08-13 | 龙广秋 | Digital-analog converter for optical fiber communication |
| CN113253540B (en) * | 2021-04-25 | 2023-01-03 | 深圳市南天威视科技有限公司 | Digital-analog converter for optical fiber communication |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20160427 Termination date: 20161117 |
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| CF01 | Termination of patent right due to non-payment of annual fee |