CN2570792Y - Multiple-testing total fibre-optical velocity interference apparatus - Google Patents

Abstract

The utility model relates to a multipoint-testing full fiber velocity interference apparatus, which is not designed yet in the prior art. The multipoint-testing full fiber velocity interference apparatus of the utility model is mainly composed of a laser device, a full fiber interference apparatus, fiber delay lines and a data processing part, wherein the full fiber interference apparatus is composed of three 2*2 fiber couplers, or can also be composed of a 2*2 fiber coupler and a 3*3 fiber coupler. After lasers are processed by the operation of light splitting and beat interference of the couplers, stable interference fringes are generated. After the interference fringes are put into photoelectrical conversion by a detector, interference curved lines and velocity profile curved lines which correspond to different test points are analyzed. The utility model utilizes the time division multiplex structure of fiber delay line members, and realizes the multipoint-testing function which can only be realized by multiple sets of single point testing full fiber velocity interferometer under the condition of no increase of signal detection facilities. The utility model has the advantages of simple structure, convenient reversal development of the velocity profile curved lines and high measuring precision.

Description

The full optical fiber speed interference device of multi-point sampler

Technical field

The utility model is a kind of interference device of specimen multiple spot speed.

Background technology

From the seventies, the laser speed interferometer has been widely used in the instantaneous velocity measurement.Though the conventional interference instrument mainly is made of discrete devices such as dozens of Precision Machining coated lens, prism and supports thereof, has debug difficulties, shortcomings such as optical loss height,, owing to its unique applications in noncontact, continuous coverage is used till today.Perfect along with the development of the maturation of optical fiber technology, photoelectric technology and solid state laser replaces the velocity interferometer that discrete devices constitutes with full optical fiber velocity interferometer, become a kind of trend.Middle nineteen nineties, the research of full optical fiber velocity interferometer has obtained significant development, Israel and China have successively successfully developed full optical fiber velocity interferometer, but there is the test weak effect, and can only realize single-spot testing, to the optical fiber velocity interferometer of sample surfaces multi-point sampler, up to the present, also there is not relevant report.And to the multi-point sampler of sample surfaces, it is very significant changing in the characteristic of research material and the states of matter under the High Temperature High Pressure, and the researcher by shock wave and detonation physical field is paid close attention to always.In order to realize multimetering, the common method of abroad taking at present is that many covers interference system of the identical performance of structure is realized this target.

Summary of the invention

The purpose of this utility model be design a kind of simple in structure, debugging is convenient, the full optical fiber speed interference device that can realize multi-point sampler.

Optical fiber length measuring device of the present utility model mainly is made up of laser instrument, full optical fiber interference device, fibre delay line, several parts of data processing.The laser that is sent by stabilized light source transfers to specimen through interference system, the light that carries sample velocities information enters interference system once more, last interference signal is received by photodetector, is finally inversed by the velocity profile curve of different test points at last by data handling system.

The utility model utilizes fiber optic passive devices such as fiber coupler, optical fiber, optical fiber collimator, and active devices such as stabilized light source and photodetector, makes the fiber optic interferometric device.This apparatus structure is as follows: enter fiber coupler II (10) by coupling mechanism (1) end after stabilized light source process fiber coupler I (9) beam split that laser instrument sends, pass through coupling mechanism III (12) again, wherein behind one road light process optical fiber collimator (13), tested sample (7) reflection, after another road light passes through fibre delay line (15) and optical fiber collimator (14), tested sample (7) reflection, behind different fibre delay lines, different light beams are by different sample reflection spot reflections; The light of process coupling mechanism III returns coupling mechanism III again after optical fiber collimator (13), (14) are reflected, after its beam split, inject coupling mechanism II at 3 and 4 ends, thereby form stable interference fringe at 1,2 ends, is detected device I, II and detects.Between optical fiber collimator (13), (14) and fiber coupler (12) is fiber coupler or fibre delay line, adds that in end of probe they can realize the multi-point sampler function.Between coupling mechanism II, III, be single-mode fiber, promptly postpone arm optical fiber.

The fiber coupler that the utility model adopted is 2 * 2 type fiber couplers or one 2 * 2 type fiber coupler and one 3 * 3 fiber coupler formation of three two ends inputs, two ends output.

Fiber coupler between optical fiber collimator (13), (14) and fiber coupler (12) is 1 * 2 or 1 * 3 fiber coupler.

Work light of the present utility model is semiconductor laser diode (LD) or semiconductor light-emitting-diode (LED), and operation wavelength is 1.31 microns, 1.55 microns, 0.85 micron, 0.63 micron.

The same with the full optical fiber velocity interferometer of single detection port, the full optical fiber velocity interferometer that can realize multi-point sampler has also utilized because the existence of time-delay τ, coherent light is by behind the all-fiber interferometer, with producing frequency is the interference fringe of coherent light Doppler frequency-shift difference Δ F, and interference fringe frequency f (t) can be expressed as $f\left(t\right)=\mathrm{\ΔF}\left(t\right)=\frac{2}{\mathrm{\λ}}[V\left(t\right)-V(t-\mathrm{\τ})]---\left(1\right)$

Owing to introduce fibre delay line in end of probe, and fibre delay line form delay the time T _iBe far longer than the time-delay τ between two coupling mechanisms, so the light that each detection port reflects is altogether irrelevant in full optical fiber speed interference system; Select suitable fibre delay line, just can intactly extract each detection port signal in the test side, final under the prerequisite that does not increase the detection system complicacy, realized multi-point sampler function to the test target surface.The intervention of lag line makes the signal of each detection port arrive the asynchronism(-nization) of test side,

Suppose that port adds up to N, at moment t _iRecord the detectable signal P of i port _i(t) be △ T in the shared time period of detection port _i, detection signal is pressed the series arrangement of detection port, and all signals can be expressed as in the test side $P\left(t\right)=\underset{i=1}{\overset{N}{\mathrm{\Σ}}}{P}_i\left(t\right)[U(t-t_i)-U(t-t_i-\mathrm{\Δ}{T}_i)]---\left(2\right)$

In the following formula,

Unit is a step function.

In order to realize the multi-point sampler function, select the fibre delay line length of suitable different detection ports to become key.The selection of lag line should not occur overlappingly with the signal of input end different port, that is to say, is as the criterion can finish time division multiplex.The fibre delay line length of first port is 0, and then the time delay of the fibre delay line of i port correspondence is $T_i\≥\underset{i=2}{\overset{i}{\mathrm{\Σ}}}\mathrm{\Δ}{T}_{i-1}---\left(3\right)$ Fibre delay line time-delay T _iWith fiber lengths L _iCorresponding pass is $T_i=\frac{1}{C}{n}_{\mathrm{eff}}{L}_i---\left(4\right)$ In the following formula, n _EffBe the equivalent refractive index of optical fiber, C is a light velocity of propagation in a vacuum.

Suppose that the time that the interference signal of first detection port begins to detect is set to t ₀=0 t _i=T _i, under the prerequisite that satisfies (3) formula, just can guarantee that the signal of all end of probe can intactly be detected in detection port; Otherwise in time overlapping of signal occur, can't intactly extract.

The utility model is compared with the full optical fiber velocity interferometer of prior art, has increased fibre delay line and optical fiber collimator II, and the system that makes does not have the vacancy port, has made full use of the injection luminous power of laser instrument.Input end in system is compared with the full optical fiber velocity interferometer that is used for single-spot testing, though without any change, by time division multiplex, can realize the detection to the multiplexed detection signal.Structure shown in Figure 2 can be finished 2 test functions to target surface; If add [2 * 2] coupling mechanism or [3 * 3] coupling mechanism and corresponding fibre delay line at two detection ports, can also realize 4 tests or 6 test functions, promptly finished two and overlapped or test function that many covering devices just can be finished with a covering device.The utility model is simple in structure, debugging is convenient, for the states of matter characteristic of research material under shock wave, has clear meaning.

Description of drawings

Fig. 1 is a structured flowchart of the present utility model.

Fig. 2 is the full optical fiber speed interference device figure of 2 tests of the present utility model.Wherein 1-4 is respectively input, the output port of fiber coupler II, the 5, the 6th, and the input port of fiber coupler III, the 7th, specimen, the 8th, laser instrument, the 9th, coupling mechanism I, the 10th, coupling mechanism II, the 11st, postpone optical fiber, the 12nd, coupling mechanism III, the 13, the 14th, optical fiber collimator, the 15th, fibre delay line, the 16th, photodetector I, the 17th, photodetector II, the 18th, data processing, the 19th, full optical fiber interference part of the present utility model.

Fig. 3 is 2 the interference curve figures of test full optical fiber interference device under the effect of low velocity impact ripple.

Embodiment

Embodiment

In the present embodiment, used laser instrument is the SOF131-B LD type stabilized light source (8) that Wuhan post and telecommunications research institute produces, and connects with wire jumper (FC/PC) to enter the single-mode optical-fibre coupler (9) that optical fiber Wuhan post and telecommunications research institute produces.Fiber coupler (9) is connected with (10), (10) are connected with (12) and also adopt wire jumper to connect.1-4 is respectively input, the output port of fiber coupler II, the 5, the 6th, and the input port of fiber coupler III.Single-mode fiber postpones arm (11) and fibre delay line (15) is " healthy and free from worry " G652 type single-mode fiber produced in USA, single-mode fiber postpones arm (11) and is connected between coupling mechanism II and the coupling mechanism III, and fibre delay line (15) is connected between coupling mechanism III and the collimating apparatus (14).Collimating apparatus (13), (14) are the FCO-155-A-C-09/FC/APC optical fiber collimator for the model that Wuhan post and telecommunications research institute produces, and connect for wire jumper with being connected also between the coupling mechanism (12).After sample 7 places collimating apparatus during test.Photodetector is that the model that the ministry of electronics industry 44 is produced is the InGaAs photodetector of GT322C500.Detector (16), (17) adopt wire jumper to be connected with fiber coupler (9), (10).With 2 full optical fiber velocity interferometer of test shown in Figure 2, practical application is tested the velocity variations situation of aluminium sample free face under the low speed collision on the Huo Bujinsen bar.Testing used light source power is 400 microwatts, and the light source spectrum width is 4 nanometers, and postponing arm fibre delay line length in the all-fiber interferometer is 20 meters, time division multiplex fibre delay line length is about 3,100 meters, and the aluminium sample is LY12, specification Φ 10 * 5, and drop bar speed is about 30m/s.Adopt digital oscilloscope as signal recorder, the oscillograph trigger pip is provided by the foil gauge on the drop bar.Under the superincumbent test condition, the interference fringe curve that obtains signal as shown in Figure 3.

Claims (4)

1, a kind of full optical fiber speed interference device of multi-point sampler, by laser instrument, the full optical fiber interference device, fibre delay line, data processing etc. are partly formed, it is characterized in that by light path device be following structure: the light that laser instrument (8) sends is through coupling mechanism I (9), enter coupling mechanism II (10) by (1), enter coupling mechanism III (12) again, be optical fiber collimator (13) thereafter, tested sample (7) reflection, another Lu Guangjing fibre delay line (15), optical fiber collimator (14), tested sample (7) reflection is in optical fiber collimator (13), (14) and be fiber coupler or fibre delay line between the fiber coupler (12); Catoptrical light path is through coupling mechanism III, coupling mechanism II, coupling mechanism I successively, and end is the interference signal of output in coupling mechanism II (2) end and coupling mechanism I (17), and last interference signal arrives detecting device.

2, the full optical fiber speed interference device of multi-point sampler according to claim 1 is characterized in that interference device is three 2 * 2 fiber couplers or 2 * 2,3 * 3 fiber couplers.

3, the full optical fiber speed interference device of multi-point sampler according to claim 1 is characterized in that fiber coupler between optical fiber collimator (13), (14) and fiber coupler (12) is 1 * 2 or 1 * 3 fiber coupler.

4, the full ray velocity interference device of multi-point sampler according to claim 1 is characterized in that laser instrument is semiconductor laser diode or semiconductor light-emitting-diode.

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