CN102937515B - Calibrating device and method of sine phase modulator peak value retardation - Google Patents

Abstract

The invention discloses a calibrating device and method of sine phase modulator peak value retardation. The calibrating device is characterized in that the device consists of a laser light source, a polarization splitting prism, a wave plate, a reflection mirror, a photoelectric detector, a controller, a lock phase amplifier and a computer. The calibrating device provided by the invention has the advantages of being compact in structure, simple and convenient to operate, capable of calibrating the peak value retardation less than half wavelength, and high in calibrating accuracy.

Description

The caliberating device of peak delay amount of sinusoidal phase modulator and scaling method

Technical field

The present invention relates to polarimetry technical field, particularly a kind of caliberating device of peak delay amount of sinusoidal phase modulator and scaling method.

Technical background

Sinusoidal phase modulation device is the polarization components of phase-delay quantity being carried out to Sine Modulated.Peak retardation is that sinusoidal phase modulation thinks highly of one of parameter wanted.Due in use easily by the impact of the factors such as environment, electrical parameter, material nature, need to demarcate peak retardation before the use of sinusoidal phase modulation device.

In first technology [1] (see R.A.Cline, W.B.Westerveld, and J.S.Risley.A new method formeasuring the retardation of a photoelastic modulator using single photon countingtechniques.Rev.Sci.Instrum.64,1169-1174,1993) a kind of method of the demarcation phase-modulator based on single photon technique is described.When measuring light intensity and being enough strong, use analog lock-in amplifier, record peak retardation by multiple harmonic rule of three.When measuring light intensity and being very weak, use the single photon counting technology of class digital lock-in amplifier, passing ratio method records peak retardation.The method can demarcate any peak retardation, but it needs to carry out in the atomic collision device under weak signal, and device is complicated.

In first technology [2] (see A.Zeng, L.Huang, Z.Dong, J.Hu, H.Huang, andX.Wang.Calibration method for a photoelastic modulator with a peak retardation of less than ahalf-wavelength.Applied Optics.46,699-703,2007) describe a kind of new method utilizing first-order bessel function maximum value process to demarcate phase-modulator.First the method utilizes the maximum of points 1.841rad of first-order bessel function to demarcate roughly, and recycling zero Bessel function and second order Bessel's function rule of three carry out Accurate Calibration.This device only need use LASER Light Source, the polarizer, wave plate, phase-modulator, analyzer and photodetector, and measuring accuracy is high.But the method demarcating steps is complicated, complex operation.

Summary of the invention

The object of the invention is to overcome above-mentioned the deficiencies in the prior art, propose a kind of caliberating device and scaling method of peak delay amount of sinusoidal phase modulator.These apparatus and method have simple, the easy to operate feature of compact conformation, device, can demarcate the peak retardation being less than half wavelength, and stated accuracy are high.

Technical solution of the present invention is as follows:

A kind of caliberating device of peak delay amount of sinusoidal phase modulator, its feature is, this device is made up of LASER Light Source, polarization splitting prism, wave plate, catoptron, photodetector, controller, lock-in amplifier and computing machine, and the position relationship of above-mentioned component is as follows:

Light beam working direction along described LASER Light Source is described polarization splitting prism successively, wave plate and catoptron, described photodetector is in the light beam that returns through described catoptron in the reflected light path of described polarization splitting prism, the signal input of the lock-in amplifier described in output termination of described photodetector, first output terminal of described controller is connected with the control end of sinusoidal phase modulation device to be calibrated, the reference signal port of the lock-in amplifier of the second output described in termination of this controller, the output signal of lock-in amplifier connects the input end of described computing machine by serial ports, through data processing, obtain the first harmonic component of output intensity and be presented on described computing machine,

Described polarization splitting prism has had partially and the polarization splitting prism of analyzing two windows, and this polarization splitting prism plays folk prescription to mutually vertical with analyzing direction, and a folk prescription of this polarization splitting prism is in the horizontal direction, and analyzing direction vertically.

Described wave plate is the wave plate of phase-delay quantity within the scope of 45 ° ~ 135 °, and the fast axis direction of this wave plate and a folk prescription of polarization splitting prism are to angle at 45 °.

Sinusoidal phase modulation device caliberating device described in utilization demarcates the method for the peak retardation of sinusoidal phase modulation device, it is characterized in that the method comprises the following steps:

1. sinusoidal phase modulation device to be calibrated is inserted between described wave plate and catoptron, the direction of described sinusoidal phase modulation device and a folk prescription of polarization splitting prism are to angle at 45 °, become 135 ° of angles with the analyzing direction of polarization splitting prism, adjustment light path makes the reflected light of sinusoidal phase modulation device consistent with the analyzing window direction of described polarization splitting prism;

2. adjust described catoptron, make reflected light successively through sinusoidal phase modulation device, wave plate and polarization splitting prism, from the analyzing window outgoing of polarization splitting prism;

3. the phase-delay quantity amplitude of sinusoidal phase modulation device is changed by described controller, described photodetectors register is from the light beam light intensity of the analyzing window outgoing of polarization splitting prism, and change electric signal into, the signal input of the lock-in amplifier described in the input of this electric signal, the signal that described controller exports connects the reference signal mouth of described lock-in amplifier, the output signal of lock-in amplifier connects the input end of described computing machine by serial ports, through data processing, obtain the first harmonic component of output intensity and be presented on described computing machine;

4., when the first harmonic component shown on described computing machine is zero, the phase-delay quantity amplitude of described controller input is the peak phase retardation of described sinusoidal phase modulation device.

Compared with first technology, technique effect of the present invention is as follows:

1. polarization splitting prism is simultaneously as the polarizer and analyzer, and compact conformation, device is simple.

2. the peak retardation of sinusoidal phase modulation device can be demarcated with first harmonic component, easy to operate.

3. use reflected light path can demarcate the peak retardation being less than half wavelength, compared with common scaling method, stated accuracy doubles.

Accompanying drawing explanation

Fig. 1 is the structured flowchart of peak delay amount of sinusoidal phase modulator caliberating device embodiment of the present invention

Embodiment

Below in conjunction with drawings and Examples, the invention will be further described, but should not limit the scope of the invention with this.

First refer to Fig. 1, Fig. 1 is the structured flowchart of peak delay amount of sinusoidal phase modulator caliberating device embodiment of the present invention.As seen from the figure, peak delay amount of sinusoidal phase modulator caliberating device of the present invention, this device is made up of LASER Light Source 1, polarization splitting prism 2, wave plate 3, catoptron 5, photodetector 6, controller 7, lock-in amplifier 8 and computing machine 9, and its position relationship is:

Light beam working direction along described LASER Light Source 1 is described polarization splitting prism 2 successively, wave plate 3 and catoptron 5, described photodetector 6 is in the light beam that returns through described catoptron 5 in the reflected light path of described polarization splitting prism 2, the signal input of the lock-in amplifier 8 described in output termination of described photodetector 6, first output terminal of described controller 7 is connected with the control end of sinusoidal phase modulation device 4 to be calibrated, the reference signal port of the lock-in amplifier 8 of the second output described in termination of this controller 7, the output signal of this lock-in amplifier 8 connects the input end of described computing machine 9 by serial ports, through data processing, obtain the first harmonic component of output intensity and be presented on described computing machine 9.

Described polarization splitting prism 2 has had partially and the polarization splitting prism of analyzing two windows, and this polarization splitting prism plays folk prescription to mutually vertical with analyzing direction, and a folk prescription of this polarization splitting prism 2 is in the horizontal direction, and analyzing direction vertically.

Described wave plate 3 is phase-delay quantity wave plates within the scope of 45 ° ~ 135 °, and the fast axis direction of wave plate 3 and a folk prescription of polarization splitting prism 2 are to angle at 45 °.

The structure of most preferred embodiment of the present invention as shown in Figure 1, its concrete structure and parameter as follows:

Described LASER Light Source 1 is the semiconductor laser of wavelength 635nm, described polarization splitting prism 2 reaches the Dual-window Glan-Taylor prism of 100000:1 for extinction ratio, described wave plate 3 is zero level quartz quarter-wave plates, described catoptron 5 for reflectivity be the reflection wedge mirror of 50%, described photodetector 6 is made up of photodiode and pre-amplification circuit, the amplitude that described controller 7 can control the phase-delay quantity of phase-modulator 4 changes within the scope of 0 ~ 2 π, described lock-in amplifier 8 is the lock-in amplifier of Hinds Instrument company Signaloc2100 model.

Peak delay amount of sinusoidal phase modulator caliberating device described in utilization demarcates the method for peak delay amount of sinusoidal phase modulator, it is characterized in that comprising the following steps:

1. sinusoidal phase modulation device 4 to be calibrated to be inserted between described wave plate 3 and catoptron 5 and to be connected with controller 7, the direction of described sinusoidal phase modulation device 4 and the direction that thoroughly the shakes angle at 45 ° playing inclined window of polarization splitting prism 2, become 135 ° of angles with the direction that thoroughly shakes of the analyzing window of polarization splitting prism 2.Adjustment light path makes reflected light successively through sinusoidal phase modulation device 4, wave plate 3 and polarization splitting prism 2, from the analyzing window outgoing of polarization splitting prism 2;

2. utilize described photodetector 6 to record light beam light intensity from the outgoing of polarization splitting prism 2 analyzing window, and change electric signal into, the input signal mouth of the lock-in amplifier 8 described in the access of this electric signal.The reference signal mouth of the signal access lock-in amplifier 8 that described controller 7 is drawn.Computing machine 9 described in the output signal of lock-in amplifier 8 is accessed by serial communication.

3. the phase-delay quantity amplitude of sinusoidal phase modulation device 4 is changed by described controller 7, described photodetector 6 records the light beam light intensity of the analyzing window outgoing from polarization splitting prism 2, and change electric signal into, the signal input of the lock-in amplifier 8 described in the input of this electric signal, the signal that described controller 7 exports connects the reference signal mouth of described lock-in amplifier 8, the output signal of this lock-in amplifier 8 connects the input end of described computing machine 9 by serial ports, through data processing, obtain the first harmonic component of output intensity and be presented on described computing machine 9:

4., when on described computing machine 9, the first harmonic component of display is zero, the amplitude of the phase-delay quantity that described controller 7 inputs is the peak phase retardation of described sinusoidal phase modulation device 4.

Jones vector through the linearly polarized light of described polarization splitting prism 2 exit window outgoing is

$G_P=\sqrt{I_0}\left[\begin{array}{c}1\\ 0\end{array}\right],---\left(1\right)$

Wherein I ₀for initial beam intensity.

Linearly polarized light first time, its Jones matrix can be expressed as when described wave plate 3

$G_W=\left[\begin{array}{cc}\cos \frac{\mathrm{\δ}}{2}+i\sin \frac{\mathrm{\δ}}{2}\cos \left(2\mathrm{\ρ}\right)& i\sin \frac{\mathrm{\δ}}{2}\sin \left(2\mathrm{\ρ}\right)\\ i\sin \frac{\mathrm{\δ}}{2}\sin \left(2\mathrm{\ρ}\right)& \cos \frac{\mathrm{\δ}}{2}-i\sin \frac{\mathrm{\δ}}{2}\cos \left(2\mathrm{\ρ}\right)\end{array}\right],---\left(2\right)$

Wherein δ and ρ is respectively phase-delay quantity and the phase retardation of described wave plate 3, and wherein the fast axis direction of wave plate 3 and a folk prescription of polarization splitting prism 2 are to angle at 45 °, i.e. ρ=45 °.

Linearly polarized light first time, its Jones matrix can be expressed as when described sinusoidal phase modulation device 4

$G_R=\left[\begin{array}{cc}\cos \frac{\mathrm{\Δ}}{2}+i\sin \frac{\mathrm{\Δ}}{2}\cos \left(2\mathrm{\θ}\right)& i\sin \frac{\mathrm{\Δ}}{2}\sin \left(2\mathrm{\θ}\right)\\ i\sin \frac{\mathrm{\Δ}}{2}\sin \left(2\mathrm{\θ}\right)& \cos \frac{\mathrm{\Δ}}{2}-i\sin \frac{\mathrm{\Δ}}{2}\cos \left(2\mathrm{\θ}\right)\end{array}\right],---\left(3\right)$

Wherein Δ and θ are respectively phase-delay quantity and the phase retardation of described sinusoidal phase modulation device 4.A folk prescription of wherein said sinusoidal phase modulation device 4 and polarization splitting prism 2 is to angle at 45 °, i.e. θ=45 °.

The Jones matrix of described catoptron 5 is

$G_M=\left[\begin{array}{cc}1& 0\\ 0& -1\end{array}\right],---\left(4\right)$

Folded light beam second time is when described sinusoidal phase modulation device 4, and its Jones matrix is expressed as

$G_R^{\′}=\left[\begin{array}{cc}\cos \frac{\mathrm{\Δ}}{2}+i\sin \frac{\mathrm{\Δ}}{2}\cos \left(2\mathrm{\θ}\right)& -i\sin \frac{\mathrm{\Δ}}{2}\sin \left(2\mathrm{\θ}\right)\\ -i\sin \frac{\mathrm{\Δ}}{2}\sin \left(2\mathrm{\θ}\right)& \cos \frac{\mathrm{\Δ}}{2}-i\sin \frac{\mathrm{\Δ}}{2}\cos \left(2\mathrm{\θ}\right)\end{array}\right],---\left(5\right)$

Wherein θ=45 °.Reflected light second time is when described wave plate 3, and its Jones matrix is

$G_W^{\′}=\left[\begin{array}{cc}\cos \frac{\mathrm{\δ}}{2}+i\sin \frac{\mathrm{\δ}}{2}\cos \left(2\mathrm{\ρ}\right)& -i\sin \frac{\mathrm{\δ}}{2}\sin \left(2\mathrm{\ρ}\right)\\ -i\sin \frac{\mathrm{\δ}}{2}\sin \left(2\mathrm{\ρ}\right)& \cos \frac{\mathrm{\δ}}{2}-i\sin \frac{\mathrm{\δ}}{2}\cos \left(2\mathrm{\ρ}\right)\end{array}\right],---\left(6\right)$

Wherein ρ=45 °.When light beam to be calibrated is from the analyzing window outgoing of described polarization splitting prism 2, polarization splitting prism 2 is as analyzer, and its Jones matrix is

$G_A=\left[\begin{array}{cc}0& 0\\ 0& 1\end{array}\right].---\left(7\right)$

The Jones vector E that described photodetector 6 detects light can be expressed as

$E=G_P{G}_W{G}_R{G}_M{G}_R^{\′}{G}_W^{\′}{G}_A=\sqrt{I_0}\left[\begin{array}{c}0\\ -i[\cos \mathrm{\Δ}\sin \mathrm{\δ}\sin 2\mathrm{\ρ}+\sin \mathrm{\Δ}({\sin }^2\frac{\mathrm{\δ}}{2}\cos 4\mathrm{\ρ}+{\cos }^4\frac{\mathrm{\δ}}{2})]\end{array}\right],---\left(8\right)$

Order $k_1=\sin \mathrm{\δ}\sin 2\mathrm{\ρ},k_2={\sin }^2\frac{\mathrm{\δ}}{2}\cos 4\mathrm{\ρ}+{\cos }^2\frac{\mathrm{\δ}}{2},$ Then formula (8) can be written as

$E=\left[\begin{array}{c}0\\ -i(k_1\cos \mathrm{\Δ}+k_2\sin \mathrm{\Δ})\end{array}\right]\sqrt{I_0},---\left(9\right)$

Then output intensity I can be expressed as

$I=E\·E^{*}=I_0[k_1^2{\cos }^2\mathrm{\Δ}+k_2^2{\sin }^2\mathrm{\Δ}+k_1{k}_2\sin \left(2\mathrm{\Δ}\right)]$

$=I_0[\frac{k_1^2+k_2^2}{2}+\frac{k_1^2-k_2^2}{2}\cos 2\mathrm{\Δ}+k_1{k}_2\sin \left(2\mathrm{\Δ}\right)].---\left(10\right)$

Phase-delay quantity Δ=the Δ of described sinusoidal phase modulation device 4 ₀sin ω t, wherein Δ ₀for the amplitude of phase-delay quantity, ω is modulating frequency.Trigonometric function can be launched into Bessel's function form by Jacobi-An Geer identical relation and Euler's formula

$\sin \left(2\mathrm{\Δ}\right)=\sin \left[2{\mathrm{\Δ}}_0\sin \left(\mathrm{\ωt}\right)\right]=\underset{2k+1}{\mathrm{\Σ}}2J_{2k+1}\left(2{\mathrm{\Δ}}_0\right)\sin \left[(2k+1)\mathrm{\ωt}\right],(k=\mathrm{0,1,2}\·\·\·)---\left(11\right)$

Containing sin (2 Δ) component in output intensity I, output intensity I is launched into Bessel's function and can obtains first harmonic component, namely described computing machine 9 records first harmonic component and is

I _1f＝2k ₁k ₂I ₀J ₁(2Δ ₀)＝KI ₀J ₁(2Δ ₀)（12）

As the first harmonic component I that computing machine 9 records _1fwhen reaching null value, the amplitude Δ of now corresponding phase-delay quantity ₀be the peak retardation of sinusoidal phase modulation device 4.

Claims (1)

1. the method utilizing the caliberating device of peak delay amount of sinusoidal phase modulator to demarcate the peak retardation of sinusoidal phase modulation device, the caliberating device of described peak delay amount of sinusoidal phase modulator is made up of LASER Light Source (1), polarization splitting prism (2), wave plate (3), catoptron (5), photodetector (6), controller (7), lock-in amplifier (8) and computing machine (9), and the position relationship of above-mentioned component is as follows:

Light beam working direction along described LASER Light Source (1) is described polarization splitting prism (2) successively, wave plate (3) and catoptron (5), described photodetector (6) is in the light beam that returns through described catoptron (5) in the reflected light path of described polarization splitting prism (2), the signal input of the lock-in amplifier (8) described in output termination of described photodetector (6), first output terminal of described controller (7) is connected with the control end of sinusoidal phase modulation device (4) to be calibrated, the reference signal port of the lock-in amplifier (8) of the second output described in termination of this controller (7), the output signal of this lock-in amplifier (8) connects the input end of described computing machine (9) by serial ports, through data processing, obtain the first harmonic component of output intensity and be presented on described computing machine (9),

Described polarization splitting prism (2) has had partially and the polarization splitting prism of analyzing two windows, this polarization splitting prism plays folk prescription to mutually vertical with analyzing direction, this polarization splitting prism play folk prescription in the horizontal direction, analyzing direction is vertically;

Described wave plate (3) is the wave plate of phase-delay quantity within the scope of 45 ° ~ 135 °, and the fast axis direction of this wave plate (3) and a folk prescription of polarization splitting prism (2) are to angle at 45 °;

It is characterized in that the method comprises the following steps:

1. sinusoidal phase modulation device (4) to be calibrated is inserted between described wave plate (3) and catoptron (5), the direction of described sinusoidal phase modulation device (4) and a folk prescription of polarization splitting prism (2) are to angle at 45 °, become 135 ° of angles with the analyzing direction of polarization splitting prism, adjustment light path makes the reflected light of sinusoidal phase modulation device (4) consistent with the analyzing window direction of described polarization splitting prism;

2. adjust described catoptron (5), make reflected light successively through sinusoidal phase modulation device (4), wave plate (3) and polarization splitting prism (2), from the analyzing window outgoing of polarization splitting prism;

3. the amplitude of the phase-delay quantity of sinusoidal phase modulation device (4) is changed by described controller (7), described photodetector (6) record is from the light beam light intensity of the analyzing window outgoing of polarization splitting prism, and change electric signal into, the signal input of the lock-in amplifier (8) described in the input of this electric signal, the signal that described controller (7) exports connects the reference signal mouth of described lock-in amplifier (8), the output signal of lock-in amplifier (8) connects the input end of described computing machine (9) by serial ports, through data processing, obtain the first harmonic component of output intensity and be presented on described computing machine (9),

4., when the first harmonic component of the upper display of described computing machine (9) is zero, the amplitude of the phase-delay quantity that described controller (7) inputs is the peak phase retardation of described sinusoidal phase modulation device (4).