CN204679246U - Double light path switches mutually with reference to high-precision A OTF performance testing device - Google Patents

Abstract

This patent discloses a kind of double light path to switch mutually with reference to high-precision A OTF performance testing device.Proving installation comprises Wavelength tunable laser, neutral density filter, aperture, Glan prism, two-dimentional electrical turntable, acousto-optic tunable filter to be checked and drive unit, reflection index glass, detector and detector whirligig, the first energy meter probe, the second energy meter probe.The laser beam of proving installation medium wavelength tunable laser outgoing is successively by obtaining the accurate one-wavelength laser of linear polarization and on vertical incidence AOTF after neutral density filter, aperture, Glan prism, radio driver applies certain radio-frequency driven to AOTF, the angle of adjustment reflection index glass, make-1 grade of light in 0 grade of light and first-order diffraction light reflex to detector and detector whirligig, realize test.This patent has that optical system for testing is compact, testing procedure concisely easy to operate, data processing method and the flow process feature such as clearly, can realize high-level efficiency test while raising measuring accuracy and system stability.

Description

Double light path switches mutually with reference to high-precision A OTF performance testing device

Technical field:

This patent relates to optical measuring technique, and specifically refer to that a kind of double light path switches mutually with reference to high-precision A OTF performance testing device, it is for realizing high-precision acousto-optic tunable filter performance test.

Background technology:

Acousto-optic tunable filter (Acousto-optic tunable filter, AOTF) be a kind of novel dispersion light-splitting device, it is based on acoustooptic effect, can realize electric tuning spectral filtering by radio frequency, the structure all solid state because of it and have good power, thermal characteristics; Because of its electric tuning spectral filtering, there is optical electivity performance flexibly; And the advantage such as it is controlled to have spectrum sample interval, and length scanning is quick.Adapt to very much spectrographic detection to flexible and efficient data acquisition requirement, this technology has been widely used in the middle of non-imaged and imaging spectral instrument equipment at present.

The light-dividing principle of AOTF: as shown in Figure 1, AOTF (is generally TeO by acousto-optic medium ₂), wave absorption device and transducer composition.When a branch of polychromatic light by a dither there is the crystal of Photoelasticity time, meet the light vector of a certain wavelength of momentum matching and sound wave vector to produce nonlinear interaction at crystals and produce diffracted beam, transmit from crystal with certain angle of diffraction, the polychromatic light that diffraction do not occur then along former light transmition direction directly from crystal outgoing, reach the effect of light splitting thus.When crystal vibration frequency changes, diffraction goes out the also corresponding change of monochromatic wavelength, thus realizes the filtering of electric tuning light.AOTF diffraction property comprises diffraction efficiency, spectral resolution etc., the relating to parameters of its performance and wavelength and crystal itself, usually needs to realize all band cover the test of AOTF diffraction property.

Utilize laser as light source, adopting energy acceptance system to carry out measurement and calculation to zero level and diffraction luminous energy, thus draw the diffraction efficiency of AOTF, is one of feasible means.But these means due to laser instrument monochromaticity restriction cannot meet the demand of AOTF being carried out to continuous spectral coverage test.Wavelength tunable laser is utilized to be another kind of feasible settling mode (patent CN 101706361) as continuously adjustabe light source, as shown in Figure 2, the method is by the continuously adjustabe of light source, and utilize beam splitter to reduce luminous energy instability to the impact of measuring accuracy, the test of broadband and degree of precision can be realized.But the method also exists limitation, main manifestations is: needing to switch the beam splitter adapting to different spectral coverage during the test of (1) wide spectrum, simultaneously for ensureing that measuring accuracy needs to test the wavelength-beam splitting curve of this beam splitter, wasting time and energy; (2) when to AOTF device ± 1 grade in certain one-level (as+1 grade) complete test after, extra installation binder is needed to another level (as-1 grade), and will light path be readjusted, operability and consistance poor; (3) deviation of basic vector and the stability of beam splitter self all will affect measuring accuracy.Patent (CN 103913297) proposes to utilize acousto-optical device self-characteristic to realize the AOTF method of testing of luminous energy reference.As shown in Figure 3, the method replaces the light intensity of measurement 0 grade of light and diffraction light by the position of exchange two energy meters, effectively can eliminate instability and the inconsistent impact on measuring of explorer response of light source.But two energy meter place-exchange processes described in the method will introduce aligned position deviation, thus impact measuring accuracy; In addition, the place-exchange of energy meter and Glan prism switch the operation of ± 1 grade of light, also inevitably cause the change of follow-up test light path, high and affect stability of instrument on operation requirements.

Summary of the invention:

The changeable assembly that utilizes that the object of this patent is to provide a kind of novelty realizes the high-precision A OTF light-splitting device performance testing device of the mutual reference of double light path.

Wherein light path switching component (reflection index glass) realizes stable, the portable switching of ± 1 grade of optical system for testing; Detector whirligig realizes double light path mutually with reference to alternately testing.This patent effectively eliminating in luminous energy instability and the inconsistent situation that affects of energy meter sonde response, can eliminate the impact on subsequent optical path system architecture while realizing the quick switch test of ± 1 grade of light path.Compared with prior art, there is the marked improvement of following several respects: method of testing and device that 1) a kind of novelty is provided, rotate the RELATED APPLICATION detection realizing double light path, form corresponding data processing formula, eliminate the AOTF diffraction property test error of luminous energy instability and the inconsistent introducing of energy meter sonde response; 2) a kind of method of testing device of novelty is provided, realizes the AOTF ± 1 grade portable stable switching of optical diffraction performance test light path.This patent has that optical system for testing is compact, testing procedure concisely easy to operate, data processing method and the flow process feature such as clearly, can realize high-level efficiency test while raising measuring accuracy and system stability.

Ultimate principle: as shown in Figure 1, according to acoustic optic interaction principle, when a branch of polychromatic light is by AOTF, this polychromatic light is divided into two bunch polarized lights, i.e. o light and e light.When RF drive frequency is applied to after on crystal, wherein after e light generation diffraction, form+1 order diffraction light (o light) and 0 grade of light; Also there is diffraction in o light, form-1 order diffraction light (e light) and 0 grade of light simultaneously.Utilize-1 grade of light after the o optical diffraction of AOTF crystal to be measured and 0 grade of luminous energy total amount consistent with incident o light ,+1 order diffraction light after e optical diffraction and also consistent with the incident e light characteristic of 0 grade of luminous energy total amount, can test diffraction property.

Method of testing and device:

1) as shown in Figure 6, proving installation comprises tunable laser 1, neutral density filter 2, aperture 3, Glan prism 4, two-dimentional electrical turntable 5, AOTF crystal to be checked and radio driver 6, reflection index glass 7, detector and detector whirligig 8.

Tunable laser 1 wavelength coverage 210nm-2300nm, power 40mW-80mW.

Neutral density filter 2 attenuation range 10%-80%.

Aperture 3 pore diameter range is at 0.05mm-0.15mm.

Reflection index glass 7 reflectivity is greater than 99%.Explorer response wavelength 210nm-2300nm, whirligig rotation angle range 0 °-180 °.

During test, the laser beam of Wavelength tunable laser 1 outgoing is successively by obtaining the accurate one-wavelength laser of linear polarization after neutral density filter 2, aperture 3, Glan prism 4 and on vertical incidence AOTF6, radio driver applies certain radio-frequency driven to AOTF6, the angle of adjustment reflection index glass 7, make 0 grade of light and wherein first-order diffraction light (as-1 grade) reflex to detector whirligig, realize test.

Wherein, the first energy meter probe 8.1 can be realized when detector whirligig (8) is in 0 ° and 180 ° and the second energy meter probe 8.2 detects alternately to 0 grade of light and the portable stable switching of-1 order diffraction light respectively, by (η is the diffraction efficiency of AOTF to be checked, and E0 is 0 grade of luminous energy that the first energy meter probe 8.1 receives when detector whirligig is in 0 °, and E1 is the now diffraction light energy that receive of the second energy meter probe 8.2; E0' is that the first energy meter probe 8.1 receives the diffraction light energy that detector whirligig is in 180 °, E1' is now second 0 grade of luminous energy receiving of energy meter probe 8.2) process, eliminate with reference to detection the impact that flashing is qualitative and energy meter sonde response is inconsistent mutually by double light path, realize the high precision measurement of diffraction efficiency of acousto-optic tunable filter;

Wherein reflect index glass 7 to rotate and the anglec of rotation in conjunction with Glan prism 4 changes the polarization state of incident light, realize the switching of AOTF-1 order diffraction light to+1 grade of light and detection light path thereof, complete the test to AOTF-1 order diffraction optical efficiency.

2) position and the parameter that reflect index glass in proving installation are determined as follows, and as shown in Figure 4, if angle of diffraction is β, mirror center is L from the distance of Exit positions, and 0 grade of light is apart from the horizontal range of the vertical range of detector to be H, M be two detectors.When crystal diffraction light is-1 grade, the position of catoptron is A, is α with the angle of horizontal direction; When diffraction light is+1 grade, the position of catoptron is B, is γ with the angle of horizontal direction.The rotation of two secondary reflection index glass meets the center that light path reflexes to two energy meter probes all just.Then according to geometric optical theory, should meet:

Angle of diffraction β, mirror center is L from the distance of Exit positions, the vertical range H of 0 grade of light distance detector is once determine, for-1 order diffraction light, the angle of itself and horizontal direction is α, and meet α > 45 ° of+β/2, the size of M is determined by above formula, when mobile reflection index glass, the angle γ of itself and horizontal direction meets following equation:

tan(2α-90°)tan(2α-90°-β)+tan(90°-2γ)tan(β-90°+2γ)＝0

Determine the reflection position of index glass and the angle of twice rotation thus.Realize ± 1 order diffraction light switch and measure.

3) in proving installation, detector and detector whirligig 8 and the first energy meter probe 8.1, second energy meter probe 8.2 possess following features: the rotating shaft of detector and detector whirligig 8 by the first energy meter probe 8.1 and the second energy meter pop one's head in 8.2 photosurfaces center and rotates with energy meter 8.1,8.2 lines of pop one's head in the plane orthogonal formed, easy switching and effectively can avoid the position deviation of energy meter exchange generation; Aperture 3 size in proving installation is less than detector photosurface size, eliminates further position and switches impact on test, realizes the stable of light path and measurement.

4) proving installation adopts wide spectrum Glan prism and rotates adjustment binder and switches and finely tune incident ray polarized light phase place, reduces polarization basic vector deviation to the impact of measuring accuracy in the simultaneous adaptation ± 1 order diffraction performance test of raising optical efficiency to the demand of light source.

Concrete analysis and explanation:

1) during test, the wavelength of adjustment Wavelength tunable laser, applies certain radio-frequency driven to AOTF6, rotates Glan prism, and rotary reflection index glass, to position A, tests the diffraction efficiency of-1 order diffraction light.0 grade of luminous energy that first energy meter probe 8.1 receives is E ₀, the diffraction light energy that the second energy meter probe 8.2 receives is E ₁; Detector whirligig is rotated 180 °, realizes two energy meter probes and alternately measure the light of two-way light, 0 grade of luminous energy that namely the second energy meter probe 8.2 receives is E ₀', the diffraction light energy that the first energy meter probe 8.1 receives is E ₁', the computing formula of diffraction efficiency is as follows:

Be analyzed as follows: consider that Wavelength tunable laser 1 energy is unstable, also there is deviation in the responsiveness of two energy meter probes of same model, the precision of test result can be reduced, realize two energy meter probes alternately measuring and effectively can improve precision by above-mentioned formulae discovery two-way light by above-mentioned detector whirligig.

If after applying certain radio-frequency driven to AOTF6, 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:

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

If the factor of influence coefficient that energy of lasers instability causes is β, the response coefficient of the first energy meter probe is a, the response coefficient of the second energy meter probe is a (1+ Δ x), Δ x is inconsistent the produced relative deviation of two energy meter sonde responses.Then the luminous energy response of two energy meter probes 8.1,8.2 acquisition is: E ₀=β ae ₀, E ₁=β a (1+ Δ x) e ₁.Keep driving frequency constant, rotary detector whirligig 180 °, two energy meter probes realize alternately measurement 0 grade of light and diffraction light, and the two luminous energy obtained is: E ₀'=β a (1+ Δ x) e ₀, E ₁'=β ae ₁, can obtain according to diffraction efficiency formula:

${\mathrm{\η}}_1=\frac{E_1}{E_1+E_0}=\frac{\mathrm{\β}a(1+\mathrm{\Δ}x)e_1}{\mathrm{\β}a(1+\mathrm{\Δ}x)e_1+{\mathrm{\βae}}_0}=\frac{(1+\mathrm{\Δ}x)e_1}{(1+\mathrm{\Δ}x)e_1+e_0}---1-3$

${\mathrm{\η}}_2=\frac{E_1^{\′}}{E_1^{\′}+E_0^{\′}}=\frac{{\mathrm{\βae}}_1}{{\mathrm{\βae}}_1+\mathrm{\βa}(1+\mathrm{\Δ}x)e_0}=\frac{e_1}{e_1+(1+\mathrm{\Δ}x)e_0}---1-4$

AOTF6 diffraction efficiency computing formula is:

$\mathrm{\η}=1-\frac{1}{\sqrt{\frac{E_1{E}_1^{\′}}{E_0{E}_0^{\′}}}+1}$

If do not carry out optical path alignment test, now the limiting error of diffraction efficiency is Δ η ', known:

Δη′＝η ₁-η _real1-5

After carrying out light path switching alternately testing, now the limiting error of diffraction efficiency is Δ η ", known:

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

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

${\mathrm{\Δ\η}}^{\′}={\mathrm{\η}}_1-{\mathrm{\η}}_{real}=\frac{{\mathrm{\η}}_{real}(1+\mathrm{\Δ}x)}{{\mathrm{\η}}_{real}(1+\mathrm{\Δ}x)+1-{\mathrm{\η}}_{real}}-{\mathrm{\η}}_{real}$

Δη″＝η-η _real＝0

Accompanying drawing 5 is η _realwhen being respectively 0.1,0.3 and 0.5, Δ η (comprises the graph of relation (Δ x span is between 0-5%) of Δ η ' and Δ η ") and Δ x.From accompanying drawing: the theoretical limit error adopting double light path to switch the method diffraction efficiency of energy meter probe whirligig alternately testing is 0, compared with not carrying out the result of alternately testing, substantially increases measuring accuracy.

The advantage of this patent is:

1) based on the characteristic of AOTF crystal, provide a kind of method of testing and device of novelty, adopt detector whirligig to realize double light path mutually with reference to alternately testing; Light path switching component (reflection index glass) is adopted to realize stable, the portable switching of ± 1 grade of optical system for testing; Effectively eliminating in luminous energy instability and the inconsistent situation that affects of energy meter sonde response, the impact on subsequent optical path system architecture while realizing the quick switch test of ± 1 grade of light path, can be eliminated.

2) diffraction efficiency formula is utilized to carry out computing to the data obtained, the theoretical limit error being obtained diffraction efficiency by theoretical error analysis is 0, compared with prior art and disposal route, substantially increase the precision of test, optical test path method based on this model can also use in other field of optical measurements goes, and has important using value and reference significance.

Accompanying drawing illustrates:

Figure 1A OTF light-dividing principle figure.

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

Fig. 3 self-reference acousto-optic tunable filter high precision diffraction property proving installation.

Fig. 4 reflects index glass and detector whirligig schematic diagram.

Fig. 5 theoretical error curve map (η _ real=0.1,0.3,0.5).

Fig. 6 double light path switches mutually with reference to high-precision A OTF performance testing device schematic diagram.

Embodiment:

As described below is a good embodiment of this patent provided according to Fig. 6, in order to architectural feature and the implementation method of this patent to be described, instead of is used for limiting the scope of this patent.

Double light path switches reference high-precision A OTF performance testing device mutually and comprises following several part:

(1) Wavelength tunable laser 1: select EKSPLA NT342/1/UV Wavelength tunable laser as light source in this implementation method, this laser instrument can produce 210nm-2300nm continuously adjustable laser beam, output power 50mW.

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

(3) aperture 3: the present embodiment selects Daheng photoelectricity GCM-57 iris.

(4) Glan prism 4: the GL15Glan-Laser Calcite Polarizers selecting Thorlabs company in the present embodiment, extinction ratio is better than 10000:1, and spectral range, between 350nm-2300n m, is tested to realize wide spectrum.

(5) two electrical turntables 5: select friendship ties 148 × 142 2 electrical turntables in the present embodiment.Range of adjustment 360 °, the ratio of gear 1:360 of motor, scale least count 0.1 °, motor synchronizing runs resolution 0.005 °.

(6) reflect index glass 7: select luxuriant rich photoelectricity silverskin catoptron OQAg-12.7 in the present embodiment, wavelength covering visible light and infrared, diameter 12.7mm, reflectivity is greater than 99%.

(7) detector and detector whirligig 8: the present embodiment selects U.S. Coherent company EPM1000 energy meter to pop one's head in, probe selects J4-09 and J45LP-MB respectively.Select Custom Prosthesis to rotate fixing mirror holder realize the fixing of energy meter probe and rotate.

Embodiment selects the middle electric 26 short-wave infrared AOTF6 developed as acousto-optic crsytal to be measured, and takes its supporting radio driver as AOTF assembly, short-wave infrared AOTF wavelength coverage 900-2300nm.Method of testing comprises following steps:

1) output wavelength of Wavelength tunable laser 1 is selected, adjust two-dimentional electrical turntable 5, after laser beam successively passes through neutral density filter, aperture, Glan prism, vertical incidence is on AOTF6 crystal, makes the light incided on crystal be linearly polarized light (e light) by rotating Glan prism adjustment Glan prism binder and finely tuning incident ray polarized light phase place;

2) radio driver applies the radio-frequency driven of corresponding frequencies to AOTF6, adjustment reflection index glass is to special angle, detector whirligig is placed in 0 °, just light path is made to reflex to the center of two energy meter probes, receive 0 grade of luminous energy by the first energy meter probe 8.1, the second energy meter probe 8.2 receives diffraction light (o light) energy;

3) keep driving frequency constant, rotary detector whirligig 180 °, realize the alternately testing of two detector probes to light path, namely receive diffraction light (o light) energy by the first energy meter probe 8.1, the second energy meter probe 8.2 receives 0 grade of luminous energy; The formula (1-1) of above-mentioned calculating diffraction efficiency is utilized to calculate the diffraction efficiency of AOTF;

4) after test being completed to+1 grade (o light) of AOTF, by rotating adjustment Glan prism binder and finely tuning incident ray polarized light phase place, thus change the polarization state being incident to the linearly polarized light of AOTF6, diffraction light is made to switch to another level (e light), and rotary reflection index glass is to ad-hoc location, repeat above-mentioned steps 1-3, complete the test to e light diffraction efficiency.

AOTF diffraction property method of testing involved by this patent is simple, light path is compact, testing procedure is concisely easy to operate, stability is strong, compare traditional AOTF diffraction efficiency method of testing, effectively reduce instability and the inconsistent impact that test result is caused of energy meter sonde response rate that LASER Light Source energy hunting causes, greatly improve measuring accuracy.By introducing reflection index glass, can realize ± the quick switch test of 1 grade of light path while eliminate impact on subsequent optical path system architecture.By introducing detector device whirligig, the RELATED APPLICATION detection of light path can be realized, eliminate the AOTF diffraction property test error of luminous energy instability and the inconsistent introducing of energy meter sonde response, effectively prevent the deviation of the position of introducing in exchange probe positions process to the impact of test result, operation is succinct, reliable and stable; By diffraction efficiency computing formula, test result is processed, improve measuring accuracy further, reduce test error.Ideal acousto-optic tunable filter high precision diffraction property proving installation in theory.

Claims (3)

1. a double light path switches mutually with reference to high-precision A OTF performance testing device, it comprises Wavelength tunable laser (1), neutral density filter (2), aperture (3), Glan prism (4), two-dimentional electrical turntable (5), acousto-optic tunable filter to be checked and drive unit (6), reflection index glass (7), detector and detector whirligig (8), the first energy meter probe (8.1), the second energy meter probe (8.2), it is characterized in that:

The laser beam of Wavelength tunable laser (1) outgoing is successively by obtaining the accurate one-wavelength laser of linear polarization after neutral density filter (2), aperture (3), Glan prism (4) and on vertical incidence AOTF (6), radio driver applies certain radio-frequency driven to AOTF (6), the angle of adjustment reflection index glass (7), make-1 grade of light in 0 grade of light and first-order diffraction light reflex to detector and detector whirligig (8), realize test.

2. a kind of double light path according to claim 1 switches mutually with reference to high-precision A OTF performance testing device, it is characterized in that: the rotating shaft of described detector and detector whirligig (8) is by the center of the first energy meter probe (8.1) on it and the second energy meter probe (8.2) photosurface and (8.1,8.2) line of popping one's head in energy meter rotates the plane orthogonal formed.

3. a kind of double light path according to claim 1 switches mutually with reference to high-precision A OTF performance testing device, and it is characterized in that, the aperture of described aperture (3) is less than detector photosurface size.