CN203881515U - Self-reference acousto-optic tunable light filter diffraction performance testing device - Google Patents

Abstract

The utility model discloses a self-reference acousto-optic tunable light filter diffraction performance testing device. The device is composed of a wavelength tunable laser, a neutral density light filtering sheet, a Glan prism, a two-dimensional electric turntable and energy meters and is used for testing diffraction efficiency and the like of an acousto-optic tunable light filter. According to the self-reference acousto-optic tunable light filter diffraction performance testing device of the utility model, based on AOTF crystal properties, 0-stage light and diffraction light which are generated after driving is performed are utilized to realize self reference, and an energy meter probe alternating test method is used in combination, and therefore, influence of instability of light energy and inconsistency of energy probe response can be effectively eliminated, and wide-spectrum and high-precision performance testing can be realized with simple optical paths and easy operation.

Description

Self-reference acousto-optic tunable filter diffraction property proving installation

Technical field:

This patent relates to optical measuring technique, specifically refers to a kind of acousto-optic tunable filter diffraction property method of testing and device that utilizes acousto-optical device self-characteristic to realize luminous energy reference, for the test of the diffraction properties such as diffraction efficiency of acousto-optic tunable filter.

Background technology:

Acousto-optic tunable filter (Acousto-optic tunable filter, AOTF) is a kind of narrow-band tunable light filter, and it is the light-splitting device of making according to acousto-optic interaction principle.The frequency that is applied to the radio-frequency driven on crystal by change is selected minute optical wavelength, thereby realizes length scanning.This technology has been widely used in non-imaging and imaging spectral instrument at present.

The light-dividing principle of AOTF: as shown in Figure 1, when a branch of polychromatic light by a dither there is the flexible crystal of optics time, the monochromatic light of a certain wavelength will produce diffraction at crystals, from crystal, transmit at a certain angle, the polychromatic light that diffraction does not occur is crossed crystal along the direct transmission of former light transmition direction, reaches thus the object of light splitting.When crystal vibration frequency changes, the also corresponding change of the monochromatic wavelength of transmissive.AOTF diffraction property comprises diffraction efficiency, spectral resolution etc., conventionally need to realize all band cover the test of AOTF diffraction property.

Utilizing laser as light source, adopt energy receiving system to carry out measurement and calculation to zero level and diffraction luminous energy, thereby draw the diffraction efficiency of AOTF, is one of feasible means.But these means are because the monochromaticity restriction of laser instrument cannot meet the demand that the continuous spectral coverage of AOTF is tested.Utilizing Wavelength tunable laser is another kind of feasible settling mode (patent CN101706361) as continuous adjustable light source, the method is by the continuous adjustability of light source, and utilize beam splitter to reduce the impact of luminous energy instability on measuring accuracy, can realize the test of broadband and degree of precision.But also there is its limitation in the method, is mainly: when 1) wide spectrum is tested, need to switch the beam splitter that adapts to different spectral coverage, need to test wavelength-beam splitting curve of this beam splitter simultaneously for assurance measuring accuracy, waste time and energy; 2) when to AOTF device ± certain one-level (as+1 grade) in 1 grade completes after test, another level (as-1 grade) needed to extra installation binder, and will readjust light path, convenience and consistance are poor; 3) stability of basic vector deviation and beam splitter self all will affect measuring accuracy.

Summary of the invention:

The object of this patent is to provide a kind of acousto-optic tunable filter diffraction property proving installation that utilizes acousto-optical device self-characteristic to be measured to realize luminous energy reference, compared with prior art, can further simplify system, when improving measuring accuracy and system stability, realize high-level efficiency test.

As shown in Figure 1, according to acoustooptic effect and acousto-optic crsytal characteristic, when a branch of polychromatic light passes through acousto-optic turnable filter, this polychromatic light is divided into two bunch polarized lights, and a branch of is o light, and a branch of is e light.Crystal adds after rf frequency, wherein, after e light generation diffraction, forms+1 order diffraction light and 0 grade of light; Also there is diffraction in o light, form-1 order diffraction light and 0 grade of light simultaneously.When above-mentioned prior art is tested, its laser instrument is linearly polarized light, and the basic vector of this linearly polarized light is without adjustable function, and when test+1 order diffraction light and-1 order diffraction light time, the basic vector of the two incident crystal to be measured differs 90 ° of phase places, need to readjust light path with coupling.In addition, the deviation effects measuring accuracy that basic vector exists.

This patent: 1) utilize-1 order diffraction light and 0 grade of luminous energy total amount after the o optical diffraction of AOTF crystal to be measured consistent with incident o light, after e optical diffraction+the also characteristic consistent with incident e light of 1 order diffraction light and 0 grade of luminous energy total amount, by alternately testing, eliminate light source and the unstable impact on measuring accuracy of detector, simplify light path and reduce again test error; 2) adopt wide spectrum Glan prism and rotation thereof to adjust binder and switch and finely tune incident ray polarized light phase place, in the simultaneous adaptation ± 1 order diffraction performance test demand of raising the efficiency and reduce the impact of polarization basic vector deviation on measuring accuracy.

As shown in Figure 3, this patent is usingd Wavelength tunable laser 1 as testing light source, light beam is successively by neutral density filter 2 and the single wavelength line polarized light of the rear formation of Glan prism 3, thereby impinge perpendicularly on AOTF51 by adjusting two-dimensional rotary platform 4, by radio driver, 52 couples of AOTF51 apply after radio-frequency driven, by the first energy meter probe 61, receive 0 grade of light, the diffraction light that the second energy meter probe 62 produces after receiving and driving, then alternately by the first energy meter probe 61, received and driven the rear diffraction light producing, the second energy meter probe 62 receives 0 grade of light and completes test.By adjusting Glan prism, realize the change of 90 ° of phase places of polarization state of the linearly polarized light that is incident to AOTF51, thereby realize the switching of ± 1 order diffraction light, realize the test of the two.

Concrete grammar: adjust the wavelength of Wavelength tunable laser, AOTF51 is applied to certain radio-frequency driven, the first energy meter probe 61 0 grade of luminous energy receiving are E ₀, the second energy meter probe 62 diffraction light energy that receive are E ₁; Exchange two energy meter probe positions, the second energy meter probe 62 0 grade of luminous energy receiving are E ₀', the first energy meter probe 61 diffraction light energy that receive are E ₁', the computing formula of diffraction efficiency is as follows:

$\mathrm{\η}=\sqrt{\frac{E_1{E}_1^{\text{'}}}{(E_0+E_1)(E_0^{\text{'}}+E_1^{\text{'}})}}---(1-1)$

Be described as follows: consider that Wavelength tunable laser 1 energy is unstable, also there is deviation in the responsiveness of two energy meter probes, can reduce the precision of test result, by can effectively improving precision after above-mentioned energy meter probe alternately testing and by above-mentioned formula calculating.

If AOTF51 is applied after certain radio-frequency driven, the actual energy of 0 grade of light is e ₀, the actual energy of diffraction light is e ₁, its ideal diffraction efficiency is:

${\mathrm{\η}}_{\mathrm{real}}=\frac{e_1}{e_1+e_0}---(1-2)$

If the factor of influence coefficient that energy of lasers is unstable caused is β, the response coefficient of the first energy meter probe is a, and the response coefficient of the second energy meter probe is a (1+ Δ x), and Δ x is two relative deviations that energy meter sonde response is inconsistent produced.The luminous energies response that two energy meters probe 61,62 obtains is: E ₀=β ae ₀, E ₁=β a (1+ Δ x) e ₁, to change after two energy meter probes, the two luminous energy of obtaining is: E ₀'=β a (1+ Δ x) e ₀, E ₁'=β ae ₁, can obtain:

${\mathrm{\η}}_1=\frac{E_1}{E_1+E_0}=\frac{\mathrm{\βa}(1+\mathrm{\Δx})e_1}{\mathrm{\βa}(1+\mathrm{\Δx})e_1+\mathrm{\βa}{e}_0}=\frac{(1+\mathrm{\Δx})e_1}{(1+\mathrm{\Δx})e_1+e_0}---(1-3)$

${\mathrm{\η}}_2=\frac{E_1^{\text{'}}}{E_1^{\text{'}}+E_0^{\text{'}}}=\frac{\mathrm{\βa}{e}_1}{\mathrm{\βa}{e}_1+\mathrm{\βa}(1+\mathrm{\Δx})e_0}=\frac{e_1}{e_1+(1+\mathrm{\Δx})e_0}---(1-4)$

AOTF51 diffraction efficiency computing formula is:

$\mathrm{\η}=\sqrt{{\mathrm{\η}}_1*{\mathrm{\η}}_2}=\sqrt{\frac{E_1{E}_1^{\text{'}}}{(E_0+E_1)(E_0^{\text{'}}+E_1^{\text{'}})}}$

If do not carry out energy meter probe alternately testing, now the error of diffraction efficiency is Δ η ', known:

Δη′＝η ₁-η _real （1-5）

Carry out after energy meter probe alternately testing, now the error of diffraction efficiency is Δ η ", known:

$\mathrm{\Δ}{\mathrm{\η}}^{\text{'}\text{'}}=\mathrm{\η}-{\mathrm{\η}}_{\mathrm{real}}=\sqrt{{\mathrm{\η}}_1*{\mathrm{\η}}_2}-{\mathrm{\η}}_{\mathrm{real}}---(1-6)$

By formula 1-2,1-3 and 1-4, formula 1-5 and 1-6 can be derived as:

$\mathrm{\Δ}{\mathrm{\η}}^{\text{'}}={\mathrm{\η}}_1-{\mathrm{\η}}_{\mathrm{real}}=\frac{{\mathrm{\η}}_{\mathrm{real}}(1+\mathrm{\Δx})}{{\mathrm{\η}}_{\mathrm{real}}(1+\mathrm{\Δx})+1-{\mathrm{\η}}_{\mathrm{real}}}-{\mathrm{\η}}_{\mathrm{real}}$

$\begin{array}{c}\mathrm{\Δ}{\mathrm{\η}}^{\text{'}\text{'}}=\mathrm{\η}-{\mathrm{\η}}_{\mathrm{real}}\\ =\frac{{\mathrm{\η}}_{\mathrm{real}}}{\sqrt{{{2\mathrm{\η}}_{\mathrm{real}}}^2-{2\mathrm{\η}}_{\mathrm{real}}+1+{\mathrm{\η}}_{\mathrm{real}}(1-{\mathrm{\η}}_{\mathrm{real}})(1+\mathrm{\Δx}+\frac{1}{1+\mathrm{\Δx}})}}-{\mathrm{\η}}_{\mathrm{real}}\end{array}$

Accompanying drawing 3, accompanying drawing 4, accompanying drawing 5 are respectively η _realbe respectively 0.1,0.3 and at 0.5 o'clock, the graph of relation of Δ η and Δ x (Δ x span is between 0-5%).From accompanying drawing: adopt energy meter probe alternately testing can effectively improve measuring accuracy, compare with the result of not carrying out alternately testing, the measuring accuracy of diffraction efficiency has improved approximately 10 ³-10 ⁴doubly.

The extinction ratio of Glan prism 3 is better than 10000:1, spectral range is greater than 350nm-2300nm, by rotation, is adjusted binder and is finely tuned incident ray polarized light phase place, changes the polarization state of the linearly polarized light that is incident to AOTF51, thereby switch ± 1 order diffraction light, meet the testing requirement of ± 1 order diffraction light.

The advantage of this patent is:

1) based on AOTF crystal property, after utilize driving, crystal to be measured produces, and 0 grade of light and diffraction light are realized self-reference, and effectively eliminate light source and the unstable impact on measuring accuracy of detector in conjunction with the method for energy meter probe alternately testing, significantly improved measuring accuracy.

2) adopt wide spectrum Glan prism, by rotation, adjust binder and switch and finely tune incident ray polarized light phase place, not only simplified light path and operation, simultaneous adaptation ± 1 order diffraction performance test demand reduce the impact of polarization basic vector deviation on measuring accuracy.

Accompanying drawing explanation:

Figure 1A OTF light splitting schematic diagram.

Fig. 2 tunable laser method AOTF diffraction property test macro schematic diagram.

Fig. 3 lg Δ η-Δ x graph of relation (η _ real=0.1).

Fig. 4 lg Δ η-Δ x graph of relation (η _ real=0.3).

Fig. 5 lg Δ η-Δ x graph of relation (η _ real=0.5).

Fig. 6 self-reference acousto-optic tunable filter high precision diffraction property proving installation schematic diagram

Embodiment:

Be a good embodiment of this patent that provides according to Fig. 6 below, in order to architectural feature and the implementation method of this patent to be described, rather than be used for limiting the scope of this patent.

The derivative performance testing device of self-reference acousto-optic tunable filter comprises following components:

(1) Wavelength tunable laser 1: in this implementation method, select EKSPLA NT342/1/UV Wavelength tunable laser as light source, this laser instrument can produce 210nm-2300nm continuously adjustable laser beam.

(2) neutral density filter 2: the present embodiment is selected Spiricon neutral density filter.

(3) Glan prism 3: in the present embodiment, adopt the GL15Glan-Laser Calcite Polarizers of Thorlabs company, extinction ratio is better than 10000:1, and spectral range is greater than 350nm-2300nm, realize wide spectrum test.

(4) two-dimentional electrical turntable 4: adopt friendship ties 148*142 two dimension electrical turntable in the present embodiment.360 ° of range of adjustment, the ratio of gear 1:360 of motor, 0.1 ° of scale least count, 0.005 ° of motor synchronizing operation resolution.

(5) energy meter probe 61,62: in the present embodiment: select the U.S. EPM1000 of Coherent company energy meter probe, probe is selected respectively J4-09 and J45LP-MB.

Embodiment selects the middle electric 26 short-wave infrared AOTF51 that develop as crystal to be measured, and takes its supporting radio driver 52 as AOTF assembly, short-wave infrared AOTF wavelength coverage 900-2300nm.Method of testing comprises following steps:

The output wavelength of 1 selected Wavelength tunable laser 1, adjusts two-dimentional electrical turntable 4, and laser beam is vertical incidence AOTF51 after neutral density filter, Glan prism successively;

2 52 pairs of radio driver AOTF51 apply certain radio-frequency driven, by the first energy meter probe 61, receive 0 grade of luminous energy, and the second energy meter probe 62 receives diffraction light energy;

3 to maintain driving frequency constant, changes two energy meter probe positions, by the first energy meter probe 61, receives diffraction light energy, and the second energy meter probe 62 receives 0 grade of luminous energy;

4 formula by above-mentioned calculating diffraction efficiency (1 1) calculate the diffraction efficiency of AOTF;

5 couples of AOTF ± certain one-level (as+1 grade) in 1 grade completes after test, by rotation, adjust Glan prism binder and finely tune incident ray polarized light phase place, thereby change the polarization state of the linearly polarized light that is incident to AOTF51, make diffraction light switch to another grade of (Ru 1 grade), repeating step 1 4, complete to another order diffraction light (Ru 1 grade) test.

This method of testing is simple, light path is easy, workable, effectively reduce LASER Light Source energy hunting and the inconsistent impact causing of energy meter sonde response, improve measuring accuracy, and can, not changing the high precision measurement of realizing fast ± 1 order diffraction light in light path situation, be comparatively desirable acousto-optic tunable filter high precision diffraction property proving installation.

Claims (1)

1. a self-reference acousto-optic tunable filter diffraction property proving installation, it comprises Wavelength tunable laser (1), neutral density filter (2), Glan prism (3), two-dimentional electrical turntable (4), energy meter probe (61,62), it is characterized in that:

Described Wavelength tunable laser (1) adopts EKSPLA NT342/1/UV Wavelength tunable laser as light source, and this laser instrument can produce 210nm-2300nm continuously adjustable laser beam;

Described neutral density filter (2) adopts Spiricon neutral density filter;

Described Glan prism (3) adopts the GL15Glan-Laser Calcite Polarizers of Thorlabs company, and extinction ratio is better than 10000:1, and spectral range is greater than 350nm-2300nm;

Described two-dimentional electrical turntable (4) adopts the two-dimentional electrical turntable of friendship ties 148 * 142,360 ° of range of adjustment, the ratio of gear 1:360 of motor, 0.1 ° of scale least count, 0.005 ° of motor synchronizing operation resolution;

Described energy meter probe (61,62) adopts the U.S. EPM1000 of Coherent company energy meter probe, and probe is selected respectively J4-09 and J45LP-MB;

The laser beam that described Wavelength tunable laser (1) sends is successively by forming single wavelength line polarized light after neutral density filter (2) and Glan prism (3), by adjusting two-dimensional rotary platform (4) light beam, impinge perpendicularly on AOTF(51), by radio driver (52) to AOTF(51) apply after radio-frequency driven, by the first energy meter probe (61), receive 0 grade of light, the diffraction light that the second energy meter probe (62) produces after receiving and driving, then alternately by the first energy meter probe (61), receive and drive the rear diffraction light producing, the second energy meter probe (62) receives 0 grade of light and completes test.