CN109342326A - A Phase Sensitive Detection Circuit of Automatic Polarimeter - Google Patents

A Phase Sensitive Detection Circuit of Automatic Polarimeter Download PDF

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Publication number
CN109342326A
CN109342326A CN201811357376.2A CN201811357376A CN109342326A CN 109342326 A CN109342326 A CN 109342326A CN 201811357376 A CN201811357376 A CN 201811357376A CN 109342326 A CN109342326 A CN 109342326A
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phase
circuit
detection circuit
sensitive detection
operational amplifier
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CN109342326B (en
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魏京辰
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SHANGHAI INSTRUMENT PHYSICAL OPTICS INSTRUMENT CO Ltd
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SHANGHAI INSTRUMENT PHYSICAL OPTICS INSTRUMENT CO Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/21—Polarisation-affecting properties

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
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  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

A kind of phase-sensitive detection circuit of automatic polarimeter of the present invention, is related to phase-sensitive detection circuit technical field.Including the tested modulated signal formed after amplification, filtering, phase shift, coupled capacitor C7 is connect with selective frequency amplifier circuit, selective frequency amplifier circuit includes the twin-T network that 50Hz signal amplifies, coupled capacitor C4 is connect with twice operational amplifier U2A is put, then coupled capacitor C5 is connect with differential amplifier circuit；Make reference signal with 50% duty ratio square wave of modulated signal identical frequency to connect via diode D1 with the detecting circuit that alternative analog switch forms.There is no motors to turn motionless problem compared with traditional structure by the present invention；Secondly as the advantage of high speed measurement, further promotes the minimum light transmission rate index of instrument；Again, can sample minimum light transmission rate index be increased to 0.1%-0.01%；Finally, with traditional higher Glan Thompson prism of price, more than the one third that can reduce complete machine cost.

Description

A kind of phase-sensitive detection circuit of automatic polarimeter
Technical field
The present invention relates to phase-sensitive detection circuit technical fields, refer specifically to a kind of phase-sensitive detection circuit of automatic polarimeter.
Background technique
At home in the measurements with external automatic polarimeter product, optical path is all made of to pass through sample tube and detect polarization The angle that light changes determines the detection method of sample optical activity.Color depth increase due to being fitted into sample in test tube will lead to Optical path signal is significantly decayed, previous high-grade automatic polarimeter product by using Glan Thompson prism as the polarizer with Analyzer, since the light transmittance of Glan Thompson prism is compared with common polaroid height, the sample that complete machine can achieve 0.1% is minimum Light rate, to maintain signal strength required for normal detection.But the price of Glan Thompson prism is higher, accounts for complete machine cost One third more than.Due to use common polaroid substitution Glan Thompson prism then complete machine only have 1% minimum light transmission rate, Reach identical effect then to need to greatly improve signal-to-noise ratio.
Summary of the invention
It is an object of the invention to overcome missing and deficiency of the existing technology, propose a kind of in the original all rotations of holding While light instrument performance indicator, the phase-sensitive detection circuit of the automatic polarimeter of signal-to-noise ratio is increased substantially.
The present invention, in order to improve the signal-to-noise ratio of instrument and distinguish the left-handed and dextrorotation of sample, needs in automatic polarimeter Faraday modulation device is used to be modulated polarised light.The measured signal that modulated signal is formed after amplification, filtering, phase shift. It is coupled to the selective frequency amplifier circuit being made of operational amplifier U2B by C7, it is specified that 50Hz signal is amplified.By C4 coupling It closes to be put by operational amplifier U2A and be twice, the differential amplifier circuit being made of operational amplifier U1B is coupled to using C5. MAX4094 is alternative analog switch, uses signal source identical with modulated signal as reference signal and is input to switch control It holds (PIN3), normally open end (PIN2) connects the output of U1B, and normal-closed end (PIN4) ground connection, common end (PIN8) connects operation amplifier The non-inverting input terminal of device U1A, holding and overturning via U1A to frequency selection signal, an available signal-to-noise ratio height at least quantity The test signal of grade.During analog switch switches between two paths of signals, the positive half cycle of 50Hz sine wave amplified signal Or negative half period is scabbled, in addition half cycle is maintained, by U1A to the positive half cycle of original 50Hz sine wave amplified signal or negative half Week is overlapped, and forms the test signal of only positive half cycle or negative half period at this time, completes left-handed to sample and dextrorotation area Point.Half-cycle signal facilitates integral to be also beneficial to improve signal resolution, thus also it can be seen that signal is attached in polarizing film extinction position Close angular dimension.
As described above, the phase-sensitive detection circuit that designs of the present invention is applied to using stepper motor and high resolution encoder Polarimeter product then can be most suitable.
Detailed description of the invention
Fig. 1 is a kind of phase-sensitive detection circuit functional block diagram of automatic polarimeter of the present invention；
Wherein, selective frequency amplifier circuit: 1, it is operational amplifier U2B；
Operational amplifier: 2, it is U2A；
Differential amplifier circuit: 3, it is that operational amplifier U1B and operational amplifier U1A is formed；
Alternative analog switch: 4, it is MAX4094.
Fig. 2 is the key wiring diagram of the embodiment of the present invention.
Specific embodiment
Below in conjunction with the good embodiment of attached drawing, the invention will be further described
A kind of phase-sensitive detection circuit of automatic polarimeter (as shown in attached drawing 1,2), including the shape after amplification, filtering, phase shift At tested modulated signal, coupled capacitor C7 connect with selective frequency amplifier circuit 1；
Selective frequency amplifier circuit 1 includes the twin-T network amplified to 50Hz signal, coupled capacitor C4 with put it is twice Operational amplifier U2A2 connection, then coupled capacitor C5 are connect with differential amplifier circuit 3；
Make reference signal with 50% duty ratio square wave of modulated signal identical frequency and inputs alternative mould via diode D1 The detecting circuit connection that quasi- switch 4 forms.
Further, the selective frequency amplifier circuit 1 is made of operational amplifier U2B.
The twin-T network by by the first potentiometer, the second potentiometer, resistance R7, R13, R14, R15 and capacitor C2, C3, C8, C9 are constituted；First potentiometer and the second potentiometer are in parallel.
The differential amplifier circuit 2 is made of operational amplifier U1B and operational amplifier U1A.
The alternative analog switch 4 is MAX4094.
Wherein, the control terminal of the alternative analog switch 4 and diode D1 input connect；Normally open end and differential amplification electricity The output end of 3 operational amplifier U1B of road connects；Normal-closed end ground connection；Common end is with 3 operational amplifier U1A's of differential amplifier circuit Non-inverting input terminal connection.
As described above, the phase-sensitive detection circuit that designs of the present invention is applied to using stepper motor and high resolution encoder Polarimeter product then can be most suitable.Firstly, previous faint test signal can not direct drive servovalve motor, and stepper motor It is driven by controller, there is no motors to turn motionless problem；Secondly as the advantage of high speed measurement, facilitates carry out over-sampling, it can Further to promote the minimum light transmission rate index of instrument；It again, can be by automatic polarimeter when using a pair of of common polaroid Can sample minimum light transmission rate index be increased to 0.1%-0.01%；Finally, with traditional higher Glan Thompson rib of price Mirror is compared, and complete machine cost one third or more can be reduced.

Claims (3)

1.一种自动旋光仪的相敏检波电路，其特征在于，包括经放大、滤波、移相后形成的被测调制信号，经耦合电容C7与选频放大电路(1)连接，经耦合电容C4与放大一倍的运算放大器U2A(2)连接，再经耦合电容C5与差分放大电路(3)连接；与调制信号相同频率的50％占空比方波作参考信号经由二极管D1与二选一模拟开关(4)组成的检波电路连接。1. a phase-sensitive detection circuit of an automatic polarimeter, is characterized in that, comprises the modulated signal under test formed after amplification, filtering, phase-shifting, is connected with frequency selective amplifier circuit (1) through coupling capacitor C7, and is connected through coupling capacitor C7. C4 is connected to the double-amplified operational amplifier U2A (2), and then connected to the differential amplifier circuit (3) through the coupling capacitor C5; the 50% duty cycle square wave of the same frequency as the modulation signal is used as the reference signal through the diode D1 and the two select one The detection circuit composed of the analog switch (4) is connected. 2.如权利要求1所述的一种自动旋光仪的相敏检波电路，其特征在于，所述选频放大电路(1)包括运算放大器U2B组成和50Hz信号进行放大的双T网络；所述双T网络由Rp1电位器、Rp2电位器、电阻R7，R13，R14，R15以及电容C2、C3、C8、C9构成；所述差分放大电路(3)由运算放大器U1B组成；所述二选一模拟开关(4)为MAX4094。2. the phase-sensitive detection circuit of a kind of automatic polarimeter as claimed in claim 1, is characterized in that, described frequency selective amplifying circuit (1) comprises the double T network that operational amplifier U2B is formed and 50Hz signal is amplified; The double-T network is composed of Rp1 potentiometer, Rp2 potentiometer, resistors R7, R13, R14, R15 and capacitors C2, C3, C8, C9; the differential amplifier circuit (3) is composed of an operational amplifier U1B; The analog switch (4) is the MAX4094. 3.如权利要求1或2所述的一种自动旋光仪的相敏检波电路，其特征在于，所述二选一模拟开关(4)的控制端与二极管D1输入连接，常开端与差分放大电路(3)运算放大器U1B的输出端连接，常闭端接地，公共端与差分放大电路(3)运算放大器U1A的同相输入端连接。3. The phase-sensitive detection circuit of an automatic polarimeter according to claim 1 or 2, wherein the control terminal of the two-choice analog switch (4) is connected to the input of the diode D1, and the normally open terminal is connected to the differential amplifier The output terminal of the circuit (3) operational amplifier U1B is connected, the normally closed terminal is grounded, and the common terminal is connected to the non-inverting input terminal of the operational amplifier U1A of the differential amplifier circuit (3).
CN201811357376.2A 2018-11-15 2018-11-15 Phase-sensitive detection circuit of automatic polarimeter Active CN109342326B (en)

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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN201503475U (en) * 2009-09-11 2010-06-09 江苏科技大学 Thyristor Arm Missing Fault Detection Circuit Based on Frequency Resonance
CN201699659U (en) * 2010-07-02 2011-01-05 中国科学技术大学 lock-in amplifier
CN102607604A (en) * 2012-03-15 2012-07-25 李建国 Phase-sensitive detection circuit
CN104660170A (en) * 2014-06-19 2015-05-27 吴春刚 Phase sensitive detection circuit
CN107124179A (en) * 2017-05-08 2017-09-01 安康学院 A kind of lock-in amplifier for detecting faint photo-signal
CN207867010U (en) * 2018-02-05 2018-09-14 南京云磁电子科技有限公司 Queen post is used for the device of ferromagnetic detection
CN209086131U (en) * 2018-11-15 2019-07-09 上海仪电物理光学仪器有限公司 A kind of phase-sensitive detection circuit of automatic polarimeter

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN201503475U (en) * 2009-09-11 2010-06-09 江苏科技大学 Thyristor Arm Missing Fault Detection Circuit Based on Frequency Resonance
CN201699659U (en) * 2010-07-02 2011-01-05 中国科学技术大学 lock-in amplifier
CN102607604A (en) * 2012-03-15 2012-07-25 李建国 Phase-sensitive detection circuit
CN104660170A (en) * 2014-06-19 2015-05-27 吴春刚 Phase sensitive detection circuit
CN107124179A (en) * 2017-05-08 2017-09-01 安康学院 A kind of lock-in amplifier for detecting faint photo-signal
CN207867010U (en) * 2018-02-05 2018-09-14 南京云磁电子科技有限公司 Queen post is used for the device of ferromagnetic detection
CN209086131U (en) * 2018-11-15 2019-07-09 上海仪电物理光学仪器有限公司 A kind of phase-sensitive detection circuit of automatic polarimeter

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