CN103292980A - Measuring device for straightness and surface response uniformity of photodetector - Google Patents

Abstract

A measuring device for straightness and surface response uniformity of a photodetector comprises a light source part, a component part and an instrument, wherein the light source part comprises a pigtailed laser with the torque of 1053 Newton meters, an optical fiber attenuator and a fiber collimator; the component part comprises a diaphragm, one fourth of a wave plate, a wedge mirror, a mirror, a power attenuator, a polarization splitting prism, an optical switch and a BNC (bayonet nut connector) T-connector; and the instrument comprises a chopper, a lock-in amplifier, an incubator, a standard detector, a to-be-tested detector, a data acquisition card and a computer. The measuring device uses the principle of a dual light path superposition method and makes use of the advantages of a laser light source of narrow linewidth and the like advantages so that the accurate measurement of the straightness and surface response uniformity of various photodetectors under a specific wavelength can be realized. Furthermore, the measuring device has the advantages of stable operation, strong anti-interference, wide dynamic range, convenient and efficient measurement and the like, and repeated measurement precision is 0.08 percent better.

Description

The measurement mechanism of photodetector linearity and face response homogeneity

Technical field

The invention belongs to detector characterisitic parameter measurement mechanism, particularly a kind of measurement mechanism for photodetector linearity and face response homogeneity.

Background technology

Linear measurement is that the optical radiation degree is learned extremely important ingredient in research and the photoelectric sensor Performance Evaluation always, and linearity is one of the most basic characterisitic parameter of detector, but generally speaking, all there is linear problem in nearly all detector, and all can only in the scope of unusual limitation, carry out for these detectors or the calibration that comprises the measuring system that these detectors are formed, most zones beyond scaling point can only estimate that result's accuracy is very poor by system linearity; General detector manufacturer does not provide the face response homogeneity of large area detector simultaneously, and this is very bad concerning the user of this index of needs.The instrument that does not have ripe measuring light electric explorer linearity in the market, the measurement of detector linearity generally all is to build test platform to measure in the laboratory that needs is arranged, the measurement result of these measurement mechanisms often is subjected to the restriction of factor affecting such as light source stability, temperature and external environment noise, especially when luminous power when 0.01 microwatt is following, the influence of noise is very big, has a strong impact on measurement result.Therefore, need the device of a kind of high-precision measurement detector linearity and face response homogeneity, the characterisitic parameter of various photodetectors is measured.

Summary of the invention

The technical problem to be solved in the present invention is to overcome above-mentioned existing technical matters and deficiency, the measurement mechanism of a kind of photodetector linearity and face response homogeneity is provided, this device should be able to be realized the accurate measurement to photodetector linearity and face response homogeneity, accurately measure between the linear zone of photodetector, should be able to realize the measurement of luminous power in the dynamic range of 0.05nw to 0.5mw, should be stable, strong, the duplicate measurements precision height of antijamming capability.

The technical scheme that the present invention solves is as follows:

The measurement mechanism of a kind of photodetector linearity and face response homogeneity, characteristics are that its formation comprises: light source, fibre optic attenuator, optical fiber collimator, diaphragm, chopper, quarter wave plate, the wedge mirror, first catoptron, second catoptron, the 3rd catoptron, power attenuator, first polarization splitting prism, second polarization splitting prism, first photoswitch, second photoswitch and BNC-T type head, first lock-in amplifier, second lock-in amplifier, the standard light electric explorer, photodetector to be measured, data collecting card, computing machine and constant temperature oven, the position relation of above-mentioned component is as follows:

Described light source, fibre optic attenuator, optical fiber collimator, diaphragm, chopper, quarter wave plate, the wedge mirror, first catoptron, second catoptron, the 3rd catoptron, power attenuator, first polarization splitting prism, second polarization splitting prism, first photoswitch, second photoswitch all places in the described constant temperature oven, single mode linearly polarized light direction along described light source output, be described fibre optic attenuator successively, optical fiber collimator, diaphragm, chopper, quarter wave plate and wedge mirror constitute main optical path, described the Lights section provides the laser output of narrow linewidth, regulate output power by fibre optic attenuator, the light path after optical fiber collimator comes out is spatial light.Described wedge mirror is divided into main optical path reference path and measures light path, the formation of described measurement light path comprises: power attenuator, first polarization splitting prism and second polarization splitting prism that light splitting surface is parallel to each other and places, described first polarization splitting prism is divided into parallel polarization light path and vertical polarization light path with incident light, described parallel polarization light path is first photoswitch successively, second catoptron, second polarization splitting prism and detector to be measured, described vertical polarization light path comprises the 3rd catoptron, second photoswitch, second polarization splitting prism and detector to be measured, described reference path is made of first catoptron and standard detector successively the reflected light direction at described wedge mirror, the equivalent optical path of the reference path from the wedge mirror to standard detector and the measurement light path from the wedge mirror to detector to be measured, the output terminal of described standard detector links to each other with the first input end of second lock-in amplifier, the output terminal of described detector to be measured links to each other with the first input end of described first lock-in amplifier, described chopper through described BNC-T type head respectively with second input end of described first lock-in amplifier, second input end of second lock-in amplifier links to each other, the output terminal of the output terminal of described first lock-in amplifier and second lock-in amplifier links to each other with input end and computer through described data collecting card, described detector to be measured is placed on the two dimensional motor tool mobile platform, and the output terminal of described computing machine links to each other with the control end of described two dimensional motor tool mobile platform.

The power of described reference path and measurement light path is regulated by fibre optic attenuator, reference path is beaten in the luminous power on the standard detector and is guaranteed between 0.1 microwatt to 200 microwatt, in the practical operation, selected fixing power, reference path no longer changes after whole optical path is adjusted.

The invention has the advantages that:

1, adopt bifocal path technique, reduced the influence that the light source shake brings, use constant temperature oven to reduce the influence of temperature and parasitic light, therefore install stablely, antijamming capability is strong.

2, utilize chopper and lock-in amplifier, can measure fainter signal, use fibre optic attenuator and power attenuator, realize higher dynamic range, therefore this device dynamic range is big, can realize the accurate measurement of linearity and face response homogeneity.

3, under the requirement condition of luminous power greater than 0.1 microwatt, also can not use lock-in amplifier to reduce cost, also can use different light sources to carry out the measurement of specific wavelength of light, therefore device is simple, uses flexibly.

Description of drawings

Fig. 1 is the measurement mechanism structural representation of photodetector linearity of the present invention and face response homogeneity

Embodiment

The invention will be further described below in conjunction with embodiment and accompanying drawing, but should not limit protection scope of the present invention with this.

See also Fig. 1, Fig. 1 is the measurement mechanism structural representation of photodetector linearity of the present invention and face response homogeneity, as can be seen from Figure 1, the formation of the measurement mechanism of photodetector linearity of the present invention and face response homogeneity comprises: light source 1, fibre optic attenuator 2 and optical fiber collimator 3, diaphragm 4, chopper 5, quarter wave plate 6, wedge mirror 8, first catoptron 7, second catoptron 14, the 3rd catoptron 13, power attenuator 9, first polarization splitting prism 10, second polarization splitting prism 15, first photoswitch 11, second photoswitch 12 and BNC-T type head 19, first lock-in amplifier 20, second lock-in amplifier 21, standard light electric explorer 16, photodetector 17 to be measured, data collecting card 22, computing machine 23 and constant temperature oven 18, the position relation of above-mentioned component is as follows:

Described light source 1, fibre optic attenuator 2, optical fiber collimator 3, diaphragm 4, chopper 5, quarter wave plate 6, wedge mirror 8, first catoptron 7, second catoptron 14, the 3rd catoptron 13, power attenuator 9, first polarization splitting prism 10, second polarization splitting prism 15, first photoswitch 11, second photoswitch 12 all places in the described constant temperature oven 18, single mode linearly polarized light direction along described light source 1 output, be described fibre optic attenuator 2 successively, optical fiber collimator 3, diaphragm 4, chopper 5, quarter wave plate 6 and wedge mirror 8 constitute main optical path, this wedge mirror 8 is divided into main optical path reference path and measures light path, the formation of described measurement light path comprises: power attenuator 9, first polarization splitting prism 10 and second polarization splitting prism 15 that light splitting surface is parallel to each other and places, described first polarization splitting prism 10 is divided into parallel polarization light path and vertical polarization light path with incident light, described parallel polarization light path is first photoswitch 11 successively, second catoptron 14, second polarization splitting prism 15 and detector to be measured 17, described vertical polarization light path comprises the 3rd catoptron 13, second photoswitch 12, second polarization splitting prism 15 and detector to be measured 17, described reference path is made of first catoptron 7 and standard detector 16 successively the reflected light direction at described wedge mirror 8, the equivalent optical path of 16 reference path and the measurement light path from wedge mirror 8 to detector 17 to be measured from wedge mirror 8 to standard detector, the output terminal of described standard detector 16 links to each other with the first input end of second lock-in amplifier 21, the output terminal of described detector to be measured 17 links to each other with the first input end of described first lock-in amplifier 20, described chopper 5 through described BNC-T type head (19) respectively with second input end of described first lock-in amplifier 20, second input end of second lock-in amplifier 21 links to each other, the output terminal of the output terminal of described first lock-in amplifier 20 and second lock-in amplifier 21 links to each other through the input end of described data collecting card 22 and computing machine 23, described detector to be measured 17 is placed on the two dimensional motor tool mobile platform, and the output terminal of described computing machine 23 links to each other with the control end of described two dimensional motor tool mobile platform.

Described light source 1 is the laser instrument of band optical fiber pigtail output.

At first carry out the light path adjustment, light path is adjusted into as shown in Figure 1, described the Lights section comprises magnetic tape trailer fibre laser 1, fibre optic attenuator 2 and optical fiber collimator 3, the three directly connects by polarization maintaining optical fibre, magnetic tape trailer fibre laser 1 output single mode linearly polarized light, wavelength 1053nm, fibre optic attenuator 2 has the attenuation range of 3 magnitudes at least, and optical fiber collimator 3 output faculas size is 0.45mm; Laser output power is adjusted to 3 milliwatts, regulating fibre optic attenuator 2 again is 2.5 milliwatts up to the output power of optical fiber collimator 3, this time is by diaphragm 4, chopper 5 and quarter wave plate 6 arrive wedge mirror 8, the reflectivity of wedge mirror 8 is 4.6%, reference path power is 0.112 milliwatt, the light of reference path is 90% through catoptron 7(reflectivity) power that arrives standard detector 16 is 0.1 milliwatt, guaranteed output is between the linear zone of standard detector 16, the transmissivity of wedge mirror 8 is 92%, the luminous power of measuring light path is 1.85 milliwatts, described power attenuator 9 has the attenuation range of 6 magnitudes, can light minimal attenuation to 2 nanowatt of light path will be measured, light is again by two polarization splitting prisms 10,15, the minimum power that arrives detector 17 to be measured is 1 nanowatt, after fibre optic attenuator 2 and power attenuator 9 combinations, actual dynamic range is 0.05nw-0.5mw.

Described chopper 5 is the square wave of characteristic frequency with optical modulation, frequency values choose to be advisable away from the ac frequency of 50Hz and multiple thereof, as it is all passable to choose 80Hz, 120Hz, 230Hz etc.; The chopping frequency of chopper 5 is connected with lock-in amplifier 20,21 by BNC-T type head 19; The output of standard detector 16 is connected with lock-in amplifier 21, and the output of detector 17 to be measured is connected with lock-in amplifier 20; Data collecting card 22 is binary channels inputs, and A channel connects lock-in amplifier 20, and the B passage connects lock-in amplifier 21, controls collection by computing machine 23 at last; Described detector to be measured 17 is placed on the two dimensional motor tool platform, carries out motion scan by the motion of computing machine 23 control two dimensional motor tool platforms.

Following hypothesis before handling, described computing machine 23 is arranged:

Order is P by the independent power that arrives detector 17 to be measured of the light of polarization splitting prism 10 parallel polarization _A, then first lock-in amplifier 20 is output as V (P _A), second lock-in amplifier 21 is output as V (P _AR); Order is P by the independent power that arrives detector 17 to be measured of the light of polarization splitting prism 10 vertical polarizations _B, then first lock-in amplifier 20 is output as V (P _B), second lock-in amplifier 21 is output as V (P _BR); The power that makes the light of parallel polarization and vertical polarization arrive detector 17 to be measured together is P _A+ P _B, then first lock-in amplifier 20 is output as V (P _A+ P _B), second lock-in amplifier 21 is output as V (P _{(A+B) R}), linearity is defined as formula:

$\mathrm{\Δ}=\frac{V\left(P_A\right)/V\left(P_{\mathrm{AR}}\right)+V\left(P_B\right)/V\left(P_{\mathrm{BR}}\right)}{V(P_A+P_B)/V\left(P_{(A+B)R}\right)}---\left(I\right)$

Regulate power attenuator 9, decay with the attenuation coefficient smaller or equal to 50% at every turn, coefficient can be set (decaying to example with 50% coefficient here), because dynamic range is 0.05nw-0.5mw, therefore 7 orders of magnitude are decayed 24 times, can obtain 24 data, calculate corresponding power (P _A+ P _B) _i(i=1,2,3 ..., 24) under linearity:

${\mathrm{\Δ}}_i=\frac{V{\left(P_A\right)}_i/V{\left(P_{\mathrm{AR}}\right)}_i+V{\left(P_B\right)}_i/V{\left(P_{\mathrm{BR}}\right)}_i}{V{(P_A+P_B)}_i/V{\left(P_{(A+B)R}\right)}_i}(i=\mathrm{1,2,3},......,24)---\left(\mathrm{II}\right)$

After supposing to finish, at first carry out the straight line degree measurement of detector 17 to be measured, described computing machine 23 carries out following processing:

When not decay of power attenuator 9, and when all opening through the photoswitch 11,12 of the light path of polarization splitting prism 10 parallel polarization and vertical polarization, the power that enters detector to be measured is 1mw, carries out following operation as benchmark:

With power attenuator 9 decay 50%, open the photoswitch 11 of the light path of parallel polarization earlier, close the photoswitch 12 of the light path of vertical polarization, computing machine 23 control data collecting cards 22 carry out data acquisition, A and B passage are gathered 1000 data respectively, A channel is asked for the mean value of 1000 data of gathering, and obtains V (P _A) ₁, the B passage is asked for the mean value of 1000 data of gathering, and obtains V (P _AR) ₁Open the photoswitch 12 of the light path of vertical polarization again, close the photoswitch 11 of the light path of parallel polarization, computing machine 23 control data collecting cards 22 carry out data acquisition, and A and B passage are gathered 1000 data respectively, A channel is asked for the mean value of 1000 data of gathering, and obtains V (P _B) ₁, the B passage is asked for the mean value of 1000 data of gathering, and obtains V (P _BR) ₁Open the photoswitch 11,12 of the light path of parallel polarization and vertical polarization then simultaneously, computing machine 23 control data collecting cards 22 carry out data acquisition, and A and B passage are gathered 1000 data respectively, and A channel is asked for the mean value of 1000 data of gathering, and obtains V (P _A+ P _B) ₁, the B passage is asked for the mean value of 1000 data of gathering, and obtains V (P _{(A+B) R}) ₁Ask for the linearity of power when 0.5mw at last:

${\mathrm{\Δ}}_1=\frac{V{\left(P_A\right)}_1/V{\left(P_{\mathrm{AR}}\right)}_1+V{\left(P_B\right)}_1/V{\left(P_{\mathrm{BR}}\right)}_1}{V{(P_A+P_B)}_1/V{\left(P_{(A+B)R}\right)}_1}---\left(\mathrm{III}\right)$

Next again with power attenuator decay 50%, repeat top operation, and power attenuator and fibre optic attenuator are used in combination, just obtained the linearity Δ of power bracket between 0.05nw-0.5mw by that analogy _i(i=1,2,3 ..., 24), shown in (II) formula, totally 24 data select linearity near 1 one (if having a plurality of, then select any one), for example Δ in these 24 data _n(1≤n≤24) near 1, the linearity correction factor θ that then makes n order _n=1, the linearity correction factor of all the other arbitrfary point m is (IV) formula so:

$\left\{\begin{array}{cc}{\mathrm{\&theta;}}_m=\underset{j=m}{\overset{n-1}{\mathrm{\&Pi;}}}{\mathrm{\&Delta;}}_j& (m<n)\\ {\mathrm{\&theta;}}_m=\underset{j=n}{\overset{m-1}{\mathrm{\&Pi;}}}{\mathrm{\&Delta;}}_j& (m>n)\end{array}\right.---\left(\mathrm{IV}\right)$

Linearity correction factor θ by gained _m(m=1,2,3 ..., 24) can judge between corresponding linear zone and quality, judge as follows:

| θ _m-1|＞0.01(m=1,2,3 ..., 24) the corresponding power interval, think that these detector 17 linearitys to be measured are poor, 0.01＜| θ _m-1|＜0.001(m=1,2,3 ..., 24) the corresponding power interval, think that these detector 17 linearitys to be measured are relatively good, at | θ _m-1|＜0.001(m=1,2,3 ..., 24) the corresponding power interval, think that then these detector 17 linearitys to be measured are very good; So far, can obtain between the linearity and required linear zone of detector 17 to be measured under different capacity.

Carrying out the face response homogeneity of detector 17 to be measured then measures, at this moment photoswitch 11,12 open all the time, the spot diameter that light beam is incident on standard detector 16 and the detector to be measured 17 is 1mm, two dimensional motor tool platform by 26 pairs of clamping detectors 17 to be measured of computing machine carries out scan control, the spacing of scan control is 1mm, the profile of scanning is square, square dimensions is that the peripheral maximum length of detector 17 test surfaces to be measured (supposes that the maximum length that records is the S millimeter, the point that then needs to scan is N, N=S * S), to comprise the whole test surface of detector 17 to be measured, the starting point of scanning lower left corner for just towards detector 17 to be measured the time is the coordinate round dot, false coordinate is (X, Y) (0≤X≤S, 0≤Y≤S).

Regulate power attenuator 9, make measuring light incide the power P of detector 17 to be measured _OSIncide the power P of standard detector (16) near reference light as far as possible _OSR=0.1 milliwatt, the standard of adjusting are that the data that A channel is gathered equal the data that the B passage is gathered as far as possible; After regulating, guarantee that position and the luminous power of measurement light path is constant, supposing to regulate the actual incident power in back is P _OS(P _OS≈ P _OSR).

Computing machine 23 control two-dimentional machinery motorized stage are carried out the test surface scanning of detector 17 to be measured, and from true origin, scanning coordinate is (X, Y) (0≤X≤S, 0≤Y≤S), detector 17 to be measured is earlier to the negative direction of principal axis motion of X-axis, carry out the one dimension horizontal scanning, horizontal scanning point is S, after horizontal scanning finishes, detector 17 to be measured is moved 1mm to the negative direction of principal axis of Y-axis, move to the X-axis positive dirction then, carry out the one dimension horizontal scanning, horizontal scanning point carries out whole scanning by that analogy for S.

In the scanning process, it is as follows that computing machine 23 control data collecting cards 22 carry out the data acquisition and processing (DAP) process:

Whenever point of scanning (X, Y) (when 0≤X≤S, 0≤Y≤S), A channel is gathered 1000 data, averaged, A channel gained result is V (P _OS) _{(X, Y)}The B passage is gathered 1000 data, averaged, and B passage gained result is V (P _OSR) _{(X, Y)}, ask for the ratio of A channel and B passage then As the response of this coordinate points, as (V) formula:

Obtaining each point (X, Y) (0≤X≤S, the response of 0≤Y≤S)

(0≤X≤S, 0≤Y≤S) afterwards, discard response

Point, keep response

Point, ask for all residual response values

Standard deviation, represent uncertainty of measurement with 3 σ, characterize the face response homogeneity of detector 17 to be measured with uncertainty of measurement, so far just obtain the face response homogeneity of detector 17 to be measured.

In sum, apparatus of the present invention can realize the accurate measurement of photodetector linearity and face response homogeneity, have stable, strong interference immunity, dynamic range big, measure advantages such as convenient and swift, the duplicate measurements precision is better than 0.08%.

Claims (2)

1. the measurement mechanism of a photodetector linearity and face response homogeneity, be characterised in that its formation comprises: light source (1), fibre optic attenuator (2) and optical fiber collimator (3), diaphragm (4), chopper (5), quarter wave plate (6), wedge mirror (8), first catoptron (7), second catoptron (14), the 3rd catoptron (13), power attenuator (9), first polarization splitting prism (10), second polarization splitting prism (15), first photoswitch (11), second photoswitch (12) and BNC-T type head (19), first lock-in amplifier (20), second lock-in amplifier (21), standard light electric explorer (16), photodetector to be measured (17), data collecting card (22), computing machine (23) and constant temperature oven (18), the position relation of above-mentioned component is as follows:

Described light source (1), fibre optic attenuator (2), optical fiber collimator (3), diaphragm (4), chopper (5), quarter wave plate (6), wedge mirror (8), first catoptron (7), second catoptron (14), the 3rd catoptron (13), power attenuator (9), first polarization splitting prism (10), second polarization splitting prism (15), first photoswitch (11), second photoswitch (12) all places in the described constant temperature oven (18), single mode linearly polarized light direction along described light source (1) output, be described fibre optic attenuator (2) successively, optical fiber collimator (3), diaphragm (4), chopper (5), quarter wave plate (6) and wedge mirror (8) constitute main optical path, this wedge mirror (8) is divided into main optical path reference path and measures light path, the formation of described measurement light path comprises: power attenuator (9), first polarization splitting prism (10) and second polarization splitting prism (15) that light splitting surface is parallel to each other and places, described first polarization splitting prism (10) is divided into parallel polarization light path and vertical polarization light path with incident light, described parallel polarization light path is first photoswitch (11) successively, second catoptron (14), second polarization splitting prism (15) and detector to be measured (17), described vertical polarization light path comprises the 3rd catoptron (13), second photoswitch (12), second polarization splitting prism (15) and detector to be measured (17), described reference path is made of first catoptron (7) and standard detector (16) successively the reflected light direction at described wedge mirror (8), the equivalent optical path of the reference path from wedge mirror (8) to standard detector (16) and the measurement light path from wedge mirror (8) to detector to be measured (17), the output terminal of described standard detector (16) links to each other with the first input end of second lock-in amplifier (21), the output terminal of described detector to be measured (17) links to each other with the first input end of described first lock-in amplifier (20), described chopper (5) through described BNC-T type head (19) respectively with second input end of described first lock-in amplifier (20), second input end of second lock-in amplifier (21) links to each other, the output terminal of the output terminal of described first lock-in amplifier (20) and second lock-in amplifier (21) links to each other through the input end of described data collecting card (22) with computing machine (23), described detector to be measured (17) is placed on the two dimensional motor tool mobile platform, and the output terminal of described computing machine (23) links to each other with the control end of described two dimensional motor tool mobile platform.

2. the measurement mechanism of photodetector linearity according to claim 1 and face response homogeneity is characterized in that: the laser instrument that described light source (1) is exported for the band optical fiber pigtail.

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