CN102735430B - Method and device for detecting phase delay - Google Patents
Method and device for detecting phase delay Download PDFInfo
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- CN102735430B CN102735430B CN201210204835.XA CN201210204835A CN102735430B CN 102735430 B CN102735430 B CN 102735430B CN 201210204835 A CN201210204835 A CN 201210204835A CN 102735430 B CN102735430 B CN 102735430B
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Abstract
The invention belongs to the technical field of laser detection, and relates to a method for detecting phase delay of an optical element by using a laser weak feedback orthogonal light intensity phase difference effect. According to method, the phase delay of the element is detected by using the phase difference effect existing between two paths of light intensity signals output by a laser in an orthogonal direction under the condition with anisotropy outer cavity laser weak feedback. The method does not have special requirements on a detected sample, and according to a detection principle, the phase delay of the detected sample is amplified, so that the sensitivity is high.
Description
Technical field
The invention belongs to technical field of laser detection, is about a kind of method and the pick-up unit thereof that utilize the strong phasic difference effect of the weak feedback orthogonal light intensity of laser to carry out detecting optical element bit phase delay.
Background technology
Bit phase delay detects the detection being mainly used in the birefringence effect that the reason such as birefringent optical element or stress produces.Wherein, most typical application is exactly the detection of wave plate retardation.Wave plate application quantity in optical system is very large, especially has a wide range of applications in the system relevant with polarized light, as optoisolator, optical filter, CD optical picking-up head, laser heterodyne interferometer, ellipsometer etc.The precision of wave plate self bit phase delay can affect the result of use of whole system, wants the application scenario of the wave plate of machining high-precision or necessary high precision determination wave plate actual bit phase retardation, all needs the method accurately detecting wave plate.Another is typically applied is exactly the internal stress detecting glass.Glass material often inevitably has unrelieved stress in process, in addition glass material with other materials in conjunction with time also have unrelieved stress, these unrelieved stresss cause the impact of can not ignore in some applied field credit union, and the method that therefore needs accurately detects this kind of unrelieved stress.Detect unrelieved stress, in fact also can be converted into the bit phase delay detecting stress birefrin and cause.
The method being widely used in wave plate retardation detection at present has rotation light extinction method and Ellipsometric.There is accuracy of detection not or the problem of complicated operation in these two kinds of methods.Rotate light extinction method and need the quarter wave plate adding a standard in the optical path, the accuracy of detection of the error meeting influential system of this standard quarter wave plate, and this error cannot predict and eliminate by rotating light extinction method system self.The light source that Ellipsometric uses is wide spectrum light source, is obtained the detection optical wavelength needed by light splitting, and the detection center wavelength of light error obtained like this is comparatively large, thus introduces metrical error.
Summary of the invention
In sum, the necessary one that provides has degree of precision, and is easy to bit phase delay detection method and the pick-up unit thereof of operation.
A kind of detection method of bit phase delay, comprise the following steps: a pick-up unit is provided, described pick-up unit comprises laser instrument, the weak feedback exocoel of laser and data Collection & Processing System, the laser original state of polarization that described laser instrument produces is linear polarization, described laser weak feedback exocoel is used for accommodating sample, and described data acquisition and processing system comprises a wollaston prism; Sample is arranged in the weak feedback exocoel of laser, make the o light of the fast axle of sample and slow-axis direction and described wollaston prism and e light two optical axis directions corresponding consistent, and to have angle with laser initial polarization direction shape; The laser sent with laser instrument irradiates described sample, and after feedback, laser instrument forms light intensity signal respectively on the fast and slow axis direction of described sample, and separates through wollaston prism, and has phasic difference between two-way light intensity signal; Receive the light intensity signal of described sample on fast and slow axis direction exported through wollaston prism with data Collection & Processing System respectively, and compare computing, obtain bit phase delay.
A kind of pick-up unit of bit phase delay, comprise: a laser instrument, described laser instrument comprises inner chamber concave mirror, gain tube, anti-reflection window, inner chamber flat output mirror are formed jointly, wherein: inner chamber concave mirror is fixed on the upper end of described gain tube, gain tube upper end and inner chamber concave mirror are fixed, lower end and anti-reflection window are fixed, and anti-reflection window is fixed on the lower end of described gain tube, inner chamber flat output mirror be positioned at described anti-reflection window below and and described anti-reflection window interval arrange; The weak feedback exocoel of one laser, described laser weak feedback exocoel comprises the interval setting successively from top to bottom of inner chamber flat output mirror, beam-expanding collimation lens combination, specimen holder, the weak catoptron of exocoel plane; One data Collection & Processing System, described data Collection & Processing System comprises wollaston prism, the first photodetector, the second photodetector, A/D converter and computing machine and jointly forms, wherein: the output light of laser instrument is divided into the component of two cross polarizations by wollaston prism along sample fast and slow axis direction; First photodetector, the second photodetector, be positioned at above wollaston prism, detects the light intensity signal on orthogonal directions respectively and convert voltage signal to; A/D converter, converts digital signal to by the voltage signal that photodetector exports and exports to computing machine; Computing machine, its input end is connected with the output terminal of described A/D converter, receives digital signal and compares computing.
The present invention utilizes half outside gas laser and outer surface level catoptron to form laser feedback system, utilizes the bit phase delay of the phasic difference effect detection optical element of light intensity curve.The optical axis direction of wollaston prism overlaps with fast (slowly) direction of principal axis of sample, thus the light that laser instrument exports is divided into two parts.This two-way light intensity signal presence bit differs, and the bit phase delay of this phasic difference and sample exists linear relationship.Measure the phasic difference between the light intensity signal on pairwise orthogonal direction, namely can obtain the bit phase delay of sample.This detection method is simple to operate, to sample without particular/special requirement, and has the potentiality that minimal stress such as being applied to unrelieved stress detects demand.
Accompanying drawing explanation
Fig. 1 is the device schematic diagram utilizing the weak feedback orthogonal light intensity of laser strong phasic difference effect detection bit phase delay described in the embodiment of the present invention;
Fig. 2 is the fast and slow axis direction of sample and the position relationship schematic diagram between laser initial polarization direction and wollaston prism optical axis direction;
Fig. 3 is the schematic diagram of the strong phasic difference effect of the weak feedback orthogonal light intensity of laser;
Fig. 4 is the lab diagram of the strong phasic difference effect of the weak feedback orthogonal light intensity of laser.
Main element symbol description
| First photodetector | 1 |
| Second photodetector | 2 |
| Wollaston prism | 3 |
| Inner chamber concave mirror | 4 |
| Gain tube | 5 |
| Anti-reflection window | 6 |
| Inner chamber flat output mirror | 7 |
| Inner chamber piezoelectric ceramics | 8 |
| Beam-expanding collimation lens combination | 9 |
| Specimen holder | 10 |
| The weak catoptron of exocoel plane | 11 |
| Exocoel piezoelectric ceramics | 12 |
| A/D converter | 13 |
| Computing machine | 14 |
| Inner chamber Piezoelectric Ceramic module | 15 |
| Exocoel Piezoelectric Ceramic module | 16 |
Following specific embodiment will further illustrate the present invention in conjunction with above-mentioned accompanying drawing.
Embodiment
Detection method and the pick-up unit of bit phase delay provided by the invention is described in detail below with reference to accompanying drawing.
As shown in Figure 1, first embodiment of the invention provides a kind of pick-up unit and method thereof of bit phase delay, and its device comprises laser instrument, the weak feedback exocoel of laser and data Collection & Processing System.
Described laser instrument both provided detection light as light source, again as the sensor receiving laser feedback, half outer (interior) cavity configuration, its original state of polarization is linear polarization, single longitudinal mode, fundamental transverse mode export, and laser type can be gas laser, semiconductor laser and solid state laser.
Described laser instrument is made up of jointly inner chamber concave mirror 4, gain tube 5, anti-reflection window 6, inner chamber flat output mirror 7 and inner chamber piezoelectric ceramics 8.Described gain tube 5 stores gain medium; Described inner chamber concave mirror 4 is fixed on the upper end of described gain tube 5; Described anti-reflection window 6 is fixed on the lower end of described gain tube 5; Described inner chamber flat output mirror 7, is positioned at the below of described anti-reflection window 6, and and described anti-reflection window 6 interval arrange; Described inner chamber piezoelectric ceramics 8 is positioned at the lower end of inner chamber flat output mirror 7, and is fixedly installed with described inner chamber flat output mirror 7.By controlling the change in voltage on described inner chamber piezoelectric ceramics 8, described inner chamber piezoelectric ceramics 8 can promote described inner chamber flat output mirror 7 and move in micro-scaled range along laser axis direction, is used for stabilized lasers output mode.Be appreciated that described inner chamber piezoelectric ceramics 8 also can substitute, as long as can promote described inner chamber flat output mirror 7 to do micron-sized movement along laser axis direction with other fine motion elements.
Described laser weak feedback exocoel is from top to bottom set gradually jointly formed by inner chamber flat output mirror 7, beam-expanding collimation lens combination 9, specimen holder 10, the weak catoptron 11 of exocoel plane, exocoel piezoelectric ceramics 12.Described beam-expanding collimation lens combination 9 is made up of concavees lens and convex lens, is positioned at below inner chamber piezoelectric ceramics 8, and and described inner chamber piezoelectric ceramics 8 interval arrange; The light that laser instrument exports can be carried out beam-expanding collimation by described beam-expanding collimation lens combination 9, makes laser beam cover certain area at sample surfaces; Position between two lens of described beam-expanding collimation lens combination 9 and between lens combination and described built in laser cavity flat output mirror 7 can regulate.The weak feedback exocoel of described laser is for holding sample, and the laser exported by built in laser cavity flat output mirror 7 can incide sample; Under the weak feedback effect of laser, the output intensity signal of laser instrument has phasic difference on sample fast and slow axis direction, and this phasic difference is determined by the bit phase delay of sample.
Specimen holder 10, is positioned at below beam-expanding collimation lens combination 9, and and described beam-expanding collimation lens combination 9 interval arrange, the laser entrance face of described specimen holder 10 can rotate perpendicular to its face normal direction; Described specimen holder 10 upper ends sample, there is light hole centre, and during detection, laser can pass from hole; Sample can carry out perpendicular to the rotation on laser axis direction with described specimen holder 10.
The weak catoptron 11 of exocoel plane, be positioned at below specimen holder 10, and and described specimen holder 10 interval arrange, with the laser reflection by passing sample, preferably, distance between the weak catoptron of described exocoel plane 11 and described inner chamber flat output mirror 7 is described inner chamber flat output mirror 7 and the integral multiple of the spacing of described inner chamber concave mirror 4, thus weakens the speckle effect existed when using semiconductor laser etc.
Exocoel piezoelectric ceramics 12, fixes with the weak catoptron 11 of described exocoel plane, and in exocoel plane weak catoptron 11 lower end; By the voltage of controlled loading on described exocoel piezoelectric ceramics 12, described exocoel piezoelectric ceramics 12 can promote the weak catoptron 11 of described exocoel plane along the to-and-fro movement of laser axis direction, makes generation continuous print can be used for the feedback waveform signal of detecting position facies relationship.
Described data Collection & Processing System in order to receive the light intensity signal on fast and slow axis direction, and compares computing, obtains bit phase delay; Export control signal, built in laser cavity length and the weak feedback external cavity length of laser are regulated.In the present invention, described " on ", D score is all based on the structure shown in Fig. 1, direction and position relationship.
Described data Collection & Processing System comprises wollaston prism 3, first photodetector 1, second photodetector 2, A/D converter 13, inner chamber Piezoelectric Ceramic module 15, exocoel Piezoelectric Ceramic module 16 and computing machine 14 and jointly forms, wherein:
Wollaston prism 3, be positioned at the top of described inner chamber concave mirror 4, described wollaston prism 3 is its plane of incidence near the surface of described inner chamber concave mirror 4, and the laser from plane of incidence incidence is divided into the component of two cross polarizations along sample fast and slow axis direction, its particular location can be selected according to actual needs, as long as ensure that laser can be incident from the plane of incidence;
First photodetector 1, second photodetector 2, is positioned at above wollaston prism 3, detects the light intensity signal through wollaston prism 3 output respectively and converts voltage signal to;
A/D converter 13, converts digital signal to by the voltage signal that the first photodetector 1, second photodetector 2 exports and exports to computing machine 14;
Inner chamber Piezoelectric Ceramic module 15, the control signal that receiving computer 14 exports, controls the flexible of inner chamber piezoelectric ceramics 8, thus drives inner chamber flat output mirror 7 trace on laser axis direction mobile, with stabilized lasers output mode;
Exocoel Piezoelectric Ceramic module 16, the control signal that receiving computer 14 exports, controls the flexible of exocoel piezoelectric ceramics 12, thus drives the weak catoptron 11 of exocoel plane along the to-and-fro movement of laser axis.
In described computing machine 14, its input end is connected with the output terminal of described A/D converter 13, receives digital signal and compares computing; Its output terminal is connected with the input end of described inner chamber Piezoelectric Ceramic module 15 and exocoel Piezoelectric Ceramic module 16, controls the motion of piezoelectric ceramics.Be appreciated that described data Collection & Processing System is not limited to above lifted element, can experimentally environment and specific requirement change.
Be appreciated that, concrete distance and the position relationship of described each element can be selected as required, as long as ensure that the laser that laser instrument sends can be irradiated to sample surfaces, and be reflected back in laser cavity through the weak catoptron 11 of exocoel plane, Laser output separates along on sample fast and slow axis direction by wollaston prism 3, can be received by the first photodetector 1 and the second photodetector 2.Preferably, described inner chamber concave mirror 4, gain tube 5, anti-reflection window 6, inner chamber flat output mirror 7, inner chamber piezoelectric ceramics 8, beam-expanding collimation lens combination 9, specimen holder 10, the weak catoptron of exocoel plane 11, exocoel piezoelectric ceramics 12 are all along the coaxial setting of axis direction of laser.
The present invention further provides a kind of detection method of bit phase delay, comprise the following steps:
First, one pick-up unit is provided, described pick-up unit comprises laser instrument, the weak feedback exocoel of laser and data Collection & Processing System, described laser instrument is in order to produce laser, and the original state of polarization of laser is linear polarization, described laser weak feedback exocoel comprises the weak catoptron of an exocoel plane, reflects laser produces laser feedback, described data acquisition and processing system is in order to sampling and processing data, described data acquisition and processing system comprises a wollaston prism, so that the laser inciding wollaston prism is divided into two bundles along its o light and e light optical axis direction;
Secondly, sample is arranged in the weak feedback exocoel of laser, make the o light of the fast axle of sample and slow-axis direction and described wollaston prism and e light two optical axis directions corresponding consistent;
Again, the laser sent with laser instrument irradiates described sample, and after feedback, laser instrument forms light intensity signal respectively on the fast and slow axis direction of described sample, and exports through wollaston prism, and has phasic difference between two-way light intensity signal;
Finally, receive the light intensity signal on the described sample fast and slow axis direction exported through wollaston prism with data Collection & Processing System respectively, and compare computing, obtain bit phase delay.
Concrete, the method utilizing the weak feedback orthogonal light intensity of laser strong phasic difference effect detection bit phase delay of the present invention, can comprise the steps:
1st step, the initial output state of laser is set as single longitudinal mode, linearly polarized light, laser is incident from the plane of incidence of wollaston prism 3, wollaston prism 3 plane of incidence is rotated perpendicular to laser axis direction, make one of two optical axis direction parallel with laser initial polarization direction, now after wollaston prism 3, emergent light only has a luminous point;
2nd step, the plane of incidence of wollaston prism 3 is rotated perpendicular to laser axis direction, after wollaston prism 3, emergent light has two luminous points, preferably, the plane of incidence of wollaston prism 3 is rotated 45 ° perpendicular to laser axis, now two optical axis directions angle all at 45 ° of laser initial polarization direction and wollaston prism 3, after wollaston prism 3, emergent light has two luminous points, the light field direction of vibration that this two luminous point is corresponding is orthogonality relation, therefore claims orthogonal light intensity;
3rd step, aligns aforementioned two luminous points respectively by the first photodetector 1, second photodetector 2;
4th step, sample is put on the specimen holder 10 of described weak feedback exocoel, perpendicular to laser axis direction rotary sample seat 10, make fast (or slow) direction of principal axis of sample parallel with laser initial polarization direction, now the light intensity signal coordination phase that receives of the first photodetector 1 and the second photodetector 2;
5th step, rotates and carries the specimen holder 10 of sample, make the fast and slow axis direction of sample and the o light of wollaston prism 3 and e light two optical axis directions corresponding consistent, and to have angle with laser initial polarization direction shape;
Being appreciated that the corresponded manner of described fast and slow axis direction and described o light and e light two optical axises is not limit, can be the corresponded manner of the corresponding o optical axis of fast axle, the corresponding e optical axis of slow axis, also can be the corresponded manner of the corresponding o optical axis of slow axis, the corresponding e optical axis of fast axle.The angle that described wollaston prism 3 is formed with laser initial polarization direction, its angular dimension is not limit.Meanwhile, the angle that the plane of incidence of described wollaston prism 3 rotates perpendicular to laser axis direction is not limit, as long as emergent light forms two luminous points.In the present embodiment, preferably, sample is rotated 45 °, now fast and slow axis direction and the laser initial polarization direction angle all at 45 ° of sample, two components of Laser output on sample fast and slow axis direction are received respectively by the first photodetector 1 and the second photodetector 2, there is phasic difference Δ φ between two light intensity signals, between this phasic difference Δ φ and bit phase delay δ of sample, there is following relation:
（*）
θ in formula
ccan be regarded as detection compensation rate, and can be obtained by examination criteria wave plate.As can be seen from formula (*), the phasic difference between the orthogonal light intensity signal of two-way is 2 times of sample bit phase delay, and therefore resolution is improved.
6th step, is gathered light intensity signal by A/D converter 13 and computing machine 14 and is compared calculating, obtains the phasic difference Δ φ of two light intensity signals, and then calculates the bit phase delay δ of sample:
（**）。
In above-mentioned steps process, computing machine 14 exports control voltage by exocoel Piezoelectric Ceramic module 16 to exocoel piezoelectric ceramics 12, thus drive the weak catoptron 11 of exocoel plane along the to-and-fro movement of laser axis direction, and control inner chamber piezoelectric ceramics 8 by inner chamber Piezoelectric Ceramic module 15, stabilized lasers output state.Preferably, described catoptron 4, gain tube 5, anti-reflection window 6, inner chamber flat output mirror 7, inner chamber piezoelectric ceramics 8, beam-expanding collimation lens combination, specimen holder, the weak catoptron of exocoel plane, the coaxial setting of exocoel piezoelectric ceramics, thus the degree of accuracy of testing result can be improved.
After being illustrated in figure 2 above-mentioned 5th step, the fast and slow axis direction of sample and the optical axis direction (o axle and e axle) of wollaston prism, and laser initial polarization direction E
iposition relationship schematic diagram, the first photodetector and the second photodetector receive the component E of Laser output on sample fast and slow axis direction respectively
sand E
f.
Be illustrated in figure 3 the schematic diagram of the strong phasic difference effect of the weak feedback orthogonal light intensity of laser, as we can see from the figure presence bit difference Δ φ between two-way light intensity signal, this phasic difference is determined by the bit phase delay of sample;
Be illustrated in figure 4 the lab diagram of the strong phasic difference effect of the weak feedback orthogonal light intensity of laser, obvious phasic difference is there is as we can see from the figure between two-way light intensity signal, this phasic difference changes with the difference of wave plate retardation, and with the difference in exocoel piezo ceramic motion direction, the phase relation between two-way light intensity signal is exchanged.
The weak feedback of laser of the present invention, belongs to the one of laser feedback phenomenon.Laser feedback (laser feedback) is also called laser self-mixing interference (self-mixing interference) or backscatter modulation (back-scattering modulation), refer to that the output beam of laser instrument is returned in laser cavity by external mirror (or object) reflection (or scattering), with light field effect in chamber, thus cause the phenomenon that laser instrument output light field changes.
Concrete, as a specific embodiment of this pick-up unit, laser instrument adopts half external cavity helium neon laser, the reflectivity R of its inner chamber concave mirror and inner chamber flat output mirror
1and R
299.6% and 99% respectively, the distance between them, namely laser intra-cavity is long is L=180mm; Be filled with He-Ne mixed gas in gain tube, inflation ratio is He
3: Ne
20: Ne
22=9:0.5:0.5; Anti-reflection window is fixed on one end of gain tube; Inner chamber piezoelectric ceramics is fixed on above-mentioned inner chamber flat output mirror, and under input voltage effect, it can promote inner chamber flat output mirror and move along laser axis direction, makes laser stabilization output state; The reflectivity R of the weak catoptron of exocoel plane
3be 4%; Exocoel piezoelectric ceramics is fixed on the weak catoptron of described exocoel plane, can promote the weak catoptron of described exocoel plane along the to-and-fro movement of laser axis direction under driving voltage effect; Tested waveplate material is quartz, diameter 11mm, and wave plate is placed on specimen holder, and specimen holder can rotate perpendicular to laser axis direction, thus drives wave plate to rotate, and there is light hole at specimen holder center, and during detection, laser passes from hole.
In addition, those skilled in the art also can do other change in spirit of the present invention, and these changes done according to the present invention's spirit, all should be included in the present invention's scope required for protection certainly.
Claims (10)
1. a detection method for bit phase delay, comprises the following steps:
One pick-up unit is provided, described pick-up unit comprises laser instrument, the weak feedback exocoel of laser and data Collection & Processing System, the laser original state of polarization that described laser instrument produces is linear polarization, described laser weak feedback exocoel comprises the weak catoptron of an exocoel plane, the weak catoptron of described exocoel plane is arranged at the below of described laser instrument, and described data acquisition and processing system comprises the top that a wollaston prism is arranged at described laser instrument;
Sample is arranged in the weak feedback exocoel of laser, make the o light of the fast axle of sample and slow-axis direction and described wollaston prism and e light two optical axis directions corresponding consistent, and to have angle with laser initial polarization direction shape;
The laser sent with laser instrument irradiates described sample, after the weak catoptron feedback of exocoel plane, laser instrument forms light intensity signal respectively on the fast and slow axis direction of described sample, and exports through wollaston prism, between two-way light intensity signal, form phasic difference;
Receive the light intensity signal of described sample on fast and slow axis direction exported through wollaston prism with data Collection & Processing System respectively, and compare computing, obtain bit phase delay.
2. the detection method of bit phase delay according to claim 1, is characterized in that, described laser instrument comprises inner chamber concave mirror, gain tube, anti-reflection window, inner chamber flat output mirror and inner chamber piezoelectric ceramics, wherein:
Inner chamber concave mirror is fixed on the upper end of described gain tube;
Gain tube upper end and inner chamber concave mirror are fixed, and lower end and anti-reflection window are fixed;
Anti-reflection window is fixed on the lower end of described gain tube;
Inner chamber flat output mirror is positioned at the below of described anti-reflection window, and and described anti-reflection window interval arrange;
Inner chamber piezoelectric ceramics and described inner chamber flat output mirror are fixed, and in inner chamber flat output mirror lower end.
3. the detection method of bit phase delay according to claim 2, is characterized in that, described laser weak feedback exocoel comprises inner chamber flat output mirror, beam-expanding collimation lens combination, specimen holder, the weak catoptron of exocoel plane, exocoel piezoelectric ceramics, wherein:
Beam-expanding collimation lens combination, is positioned at below inner chamber piezoelectric ceramics, and and described inner chamber piezoelectric ceramics interval arrange;
Specimen holder, is positioned at below beam-expanding collimation lens combination, and and described beam-expanding collimation lens combination interval arrange;
The weak catoptron of exocoel plane is positioned at below specimen holder, and and described beam-expanding collimation lens combination interval arrange;
Exocoel piezoelectric ceramics and the weak catoptron of described exocoel plane are fixed, and in the weak catoptron lower end of exocoel plane.
4. the detection method of bit phase delay according to claim 3, it is characterized in that, described data Collection & Processing System comprises wollaston prism, the first photodetector, the second photodetector, A/D converter, inner chamber Piezoelectric Ceramic module, exocoel Piezoelectric Ceramic module and computing machine, wherein:
The output light of laser instrument is divided into the component of two cross polarizations by wollaston prism along sample fast and slow axis direction;
First photodetector, the second photodetector, be positioned at above wollaston prism, detects the light intensity signal on orthogonal directions respectively and convert voltage signal to;
A/D converter, converts digital signal to by the voltage signal that photodetector exports and exports to computing machine;
Inner chamber Piezoelectric Ceramic module, the control signal that receiving computer exports, controls the flexible of inner chamber piezoelectric ceramics, thus drives inner chamber flat output mirror trace on laser axis direction mobile;
Exocoel Piezoelectric Ceramic module, the control signal that receiving computer exports, controls the flexible of exocoel piezoelectric ceramics, thus drives the weak catoptron of exocoel plane along the to-and-fro movement of laser axis;
Computing machine, its input end is connected with the output terminal of described A/D converter, receives digital signal and compares computing; Its output terminal is connected with the input end of described inner chamber Piezoelectric Ceramic module and exocoel Piezoelectric Ceramic module, controls the motion of inner chamber piezoelectric ceramics and exocoel piezoelectric ceramics.
5. the detection method of bit phase delay according to claim 4, is characterized in that, comprises the steps: further
1st step, rotated perpendicular to laser axis by the wollaston prism plane of incidence, make one of the o light of wollaston prism and e light two optical axis directions parallel with laser initial polarization direction, now after wollaston prism, emergent light only has a luminous point;
2nd step, the wollaston prism plane of incidence is rotated 45 ° perpendicular to laser axis, make two optical axis directions angle all at 45 ° of laser initial polarization direction and wollaston prism, now after wollaston prism, emergent light has two luminous points, the light field direction of vibration that these two luminous points are corresponding is orthogonality relation, forms orthogonal light intensity;
3rd step, aligns described two luminous points respectively by the first photodetector, the second photodetector;
4th step, sample is arranged at the specimen holder of the weak feedback exocoel of described laser, and specimen holder is rotated perpendicular to its plane of incidence normal direction, make the fast of sample or slow-axis direction parallel with laser initial polarization direction, the now light intensity signal coordination phase that arrives of the first photodetector and the second photoelectric detector;
5th step, the laser entrance face of sample is rotated 45 ° perpendicular to plane of incidence normal direction direction, make the fast and slow axis direction of sample and laser initial polarization direction angle all at 45 °, and the fast and slow axis direction of sample is consistent with two optical axis directions of wollaston prism, on sample fast and slow axis direction, two components of Laser output are received respectively by the first photodetector and the second photodetector, occur phasic difference between the light intensity signal of described two components
this phasic difference
and there is following relation between the bit phase delay δ of sample:
θ in formula
cbe detect compensation rate, and obtained by examination criteria wave plate;
6th step, compares calculating by A/D converter and computer acquisition light intensity signal, obtains the phasic difference of two light intensity signals
and then calculate the bit phase delay δ of sample:
6. the detection method of bit phase delay according to claim 5, it is characterized in that, in above-mentioned steps process, computing machine exports control voltage by exocoel Piezoelectric Ceramic module to exocoel piezoelectric ceramics, thus drive the weak catoptron of exocoel plane along the to-and-fro movement of laser axis direction, and control inner chamber piezoelectric ceramics by inner chamber Piezoelectric Ceramic module, stabilized lasers output state.
7. the detection method of bit phase delay according to claim 2, is characterized in that, the distance between described inner chamber flat output mirror and the weak catoptron of exocoel plane is the integral multiple of the spacing of described inner chamber flat output mirror and described inner chamber concave mirror.
8. the detection method of bit phase delay according to claim 3, it is characterized in that, described inner chamber concave mirror, gain tube, anti-reflection window, inner chamber flat output mirror, inner chamber piezoelectric ceramics, beam-expanding collimation lens combination, specimen holder, the weak catoptron of exocoel plane, the coaxial setting of exocoel piezoelectric ceramics.
9. a pick-up unit for bit phase delay, comprising:
One laser instrument, described laser instrument comprises inner chamber concave mirror, gain tube, anti-reflection window, inner chamber flat output mirror, wherein: inner chamber concave mirror is fixed on the upper end of described gain tube, gain tube upper end and inner chamber concave mirror are fixed, lower end and anti-reflection window are fixed, anti-reflection window is fixed on the lower end of described gain tube, inner chamber flat output mirror be positioned at described anti-reflection window below and and described anti-reflection window interval arrange;
The weak feedback exocoel of one laser, described laser weak feedback exocoel comprises the interval setting successively from top to bottom of inner chamber flat output mirror, beam-expanding collimation lens combination, specimen holder, the weak catoptron of exocoel plane;
One data Collection & Processing System, described data Collection & Processing System comprises wollaston prism, the first photodetector, the second photodetector, A/D converter and computing machine, wherein:
The output light of laser instrument is divided into the component of two cross polarizations by wollaston prism along sample fast and slow axis direction;
First photodetector, the second photodetector, be positioned at above wollaston prism, detects the light intensity signal on orthogonal directions respectively and convert voltage signal to;
A/D converter, converts digital signal to by the voltage signal that photodetector exports and exports to computing machine;
Computing machine, its input end is connected with the output terminal of described A/D converter, receives digital signal and compares computing.
10. the pick-up unit of bit phase delay as claimed in claim 9, is characterized in that, comprise further:
One inner chamber Piezoelectric Ceramic module, the control signal that receiving computer exports, controls the flexible of inner chamber piezoelectric ceramics, thus drives inner chamber flat output mirror to carry out micron-sized movement on laser axis direction;
One exocoel Piezoelectric Ceramic module, the control signal that receiving computer exports, controls the flexible of exocoel piezoelectric ceramics, thus drives the weak catoptron of exocoel plane along the to-and-fro movement of laser axis.
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| CN103018747A (en) * | 2012-11-26 | 2013-04-03 | 中国人民解放军第四军医大学 | Laser self-mixing distance measuring system based on uncollimated feedback external cavity |
| CN103185550B (en) * | 2013-03-13 | 2015-08-12 | 清华大学 | The measuring method of rotational angle |
| CN103337784B (en) * | 2013-06-25 | 2016-06-15 | 清华大学 | A kind of laser polarization state control method based on polarized light feedback |
| CN104571141B (en) * | 2014-11-26 | 2017-06-16 | 中国人民解放军第二炮兵装备研究院第三研究所 | A kind of object verticality adjusting device and method based on optics feedback effect |
| CN105043612B (en) * | 2015-07-13 | 2017-11-14 | 清华大学 | A kind of optical material stress measurement system |
| KR102041807B1 (en) * | 2016-09-02 | 2019-11-07 | 주식회사 엘지화학 | Device for testing optical properties and method for testing optical properties |
| CN109813227B (en) * | 2017-11-20 | 2021-01-05 | 中国人民解放军第四军医大学 | Laser cavity tuning-based multiple feedback displacement measuring device and measuring method |
| EP4004639B1 (en) * | 2019-07-26 | 2023-12-27 | Magic Leap, Inc. | Panel retardance measurement |
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