CN101398294A - Compact all optical fiber displacement interferometer - Google Patents
Compact all optical fiber displacement interferometer Download PDFInfo
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- CN101398294A CN101398294A CNA2008100462024A CN200810046202A CN101398294A CN 101398294 A CN101398294 A CN 101398294A CN A2008100462024 A CNA2008100462024 A CN A2008100462024A CN 200810046202 A CN200810046202 A CN 200810046202A CN 101398294 A CN101398294 A CN 101398294A
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Abstract
The invention discloses a compact all-fiber displacement interferometer, components of which are all connected by pigtailed fibers, and testing laser is transmitted completely inside optical fibers; an optical fiber laser and an optical fiber separator are sequentially connected with one end of a ratio-variable beam splitter, another two ends of the ratio-variable beam splitter are respectively connected with an adjustable optical fiber attenuator and an optical fiber circulator, and another two ends of the optical fiber circulator are respectively connected with an optical fiber amplifier and an APC ceramic ferrule that has pigtailed fibers and is used as an optical probe; the optical fiber amplifier is connected with an optical fiber filter, one end of an optical fiber coupler is respectively connected with the adjustable optical fiber attenuator and the optical fiber filter, the other end of the optical fiber coupler is connected with one end of a photoelectric converter, and the other end of the photoelectric converter is connected with an oscillograph in peripheral equipments. The compact all-fiber displacement interferometer can identify the movement direction changes of a measured object, has small instrument volume, compact structure and high signal to noise ratio, and does not need debugging.
Description
Technical field
The invention belongs to laser testing device field, be specifically related to compact all optical fiber displacement interferometer.
Background technology
The laser displacement interferometer is a kind of instrument that tests the speed that is based upon on the Doppler's principle basis, its working mechanism is as follows: the outgoing light wave of laser instrument is radiated at the surface of moving object to be measured, and laser light reflected produces small frequency change because of Doppler (Doppler) effect.Again reflector laser and laser instrument intrinsic are swashed combiner generation beat interference, by photoelectric commutator and oscillograph recording difference frequency change procedure.Thereby can be non-contactly, the change procedure of follow-on test surface of moving object (perhaps internal particle) displacement, speed and acceleration.Laser displacement interferometer and laser speed interferometer all are important testing tools in shock wave physics and the detonation physics research field, have wide application prospects in fields such as Condensed Matter Physics, shock dynamics, material science.
The Michelson interferometer that early stage laser displacement interferometer is made up of discrete optical components and parts (as beam splitter and catoptron) (Michelson ' s Interferometer), because can only be used for testing the mirror reflection surface motion, and the signal frequency that produces is too high, the photoelectric commutator and the oscillographic speed of response have been exceeded, so be difficult to promote the range of application of displacement interference instrument.Fluid Physics Inst., China Engineering Physics Academy disclosed one piece of article (Optical-fiber interferometer for velocity measurements with picosecondresolution) on the volume in 2006 the 89th at APPLIED PHYSICS LETTERS publication, a kind of full-optical-fiber laser displacement interferometer technology that the psec temporal resolution can be measured any reflecting surface movement velocity that has introduced in article, be called for short DISAR (displacement interferometer system for anyreflector), this technology has been applied for Chinese invention patent, patent name is " a kind of all-fiber displacement interference instrument ", the patent No.: 200510022172.X, DISAR can measure the movement velocity history of kinds of surface, as the plane, cylinder and sphere etc.
But the optic test probe size of DISAR is bigger, and cost is higher, the probe debug difficulties.Therefore, in some research fields of shock wave physics, for example drive in the film flying Study on Technology problem, because the laboratory sample size is less, experiment number is more in Laser Driven film flying technology and magnetic, need the underspeed consumables cost of tester reduces the size of test probe; Secondly, because observing time is shorter, measuring the depth of field only needs several millimeters just can satisfy most of test request, therefore need not or be inconvenient to use the DISAR instrument in above-mentioned experimental study.
Summary of the invention
The invention provides a kind of compact all optical fiber displacement interferometer, the diameter of test probe has only several millimeters even littler, with low cost, instrument integrated level height, can be applied to shock wave physics and detonation Physical Experiment, impact sample free face or internal particle moving displacement history under the loading at several millimeters field depth build-in tests, and can differentiate that direction of motion changes.
All-fiber displacement interference instrument of the present invention, characteristics are that interferometer and test probe are made up of the fiber optic element device entirely, comprise fiber laser, fibre optic isolater, no-load voltage ratio beam splitter, optical fiber circulator, adjustable optic fibre attenuator, fiber amplifier, optical fiber filter, fiber coupler and photoelectric commutator, above-mentioned fiber optic element device all connects by optical fiber.Its annexation is, fiber laser, fibre optic isolater and no-load voltage ratio beam splitter one end are connected successively, the no-load voltage ratio beam splitter is connected with optical fiber circulator with the adjustable optic fibre attenuator respectively at two ends in addition, and the two ends in addition of optical fiber circulator are connected with APC (Angle planeconnection) ceramic contact pin of fiber amplifier and magnetic tape trailer fibre respectively; Fiber amplifier is connected with optical fiber filter, one end of fiber coupler is connected with optical fiber filter with the adjustable optic fibre attenuator respectively, the other end of fiber coupler is connected with an end of photoelectric commutator, and the photoelectric commutator other end is connected with oscillograph in the peripherals.Interferometer and optic probe are made up of optical fiber entirely, the system architecture compactness, and volume is small and exquisite.The fiber coupler that adopts in the interferometer is any one in 3 * 3 fiber couplers, 2 * 2 fiber couplers or 1 * 2 fiber coupler.
Directly the APC ceramic contact pin that adopts the magnetic tape trailer fibre can realize that the height of system is integrated on the one hand as optic probe; On the other hand,, can strengthen the reflective light intensity on surface to be measured, thereby help improving the contrast of interference signal and realize high-resolution displacement measurement by fiber amplifier because the fiber end face reflected light of APC ceramic contact pin can be ignored substantially.
Peg graft by ring flange between the fiber optic element device, also can connect by the tail optical fiber welding.
The peripherals supporting with all-fiber displacement interference instrument comprises laser instrument, photoelectric commutator and oscillograph.
Under the enough situations of fiber laser output power, what geometric ratio fiber optic splitter as long as peg graft (1 * 2 or 1 * 3 fiber optic splitter all can) in the fibre optic isolater back, laser is divided into multi beam, continue again and overlap other elements except that fiber laser and isolator in the all-fiber displacement interference instruments more, the motion of a plurality of measured points on the test target simultaneously.
All-fiber displacement interference instrument of the present invention, fiber laser wherein produces the 1550nm narrow-linewidth laser.Isolator can be unidirectional by laser, but stop reciprocal laser to pass through.The no-load voltage ratio beam splitter is one 1 * 2 fiber optic splitter, from single tail optical fiber end input, and the two tail optical fibers output of double tail fiber end.The no-load voltage ratio beam splitter is unequal from the luminous power of two tail optical fibers output, and in this displacement interferometer, a tail optical fiber only occupies 5～10% of total output, the light of another tail optical fiber output more than 90%.Optical fiber circulator has three ports, and light is from wherein " 1 " port input, and from the output of " 2 " port, the light of sample surfaces reflection is exported from " 3 " port from the input of " 2 " port.When adopting 3 * 3 fiber couplers in the interferometer, 3 * 3 fiber coupler input ends and output terminal respectively have three tail optical fibers, when a branch of light during from tail optical fiber input of input end, produce three tunnel outputs of splitting ratio 1:1:1, when two bundle differentiated laser of frequency (coherent light) during from the input of two tail optical fibers of input end, produce beat frequency interference in 3 * 3 fiber couplers, carry-out bit differs 120 ° three road light signals.
The object of the present invention is achieved like this, is example with the interferometer that adopts 3 * 3 fiber couplers.Fiber laser output wavelength 1550nm laser, through behind the isolator, enter the no-load voltage ratio beam splitter and be divided into the unequal two-beam of power, wherein the first bundle light is about 5～10% of general power, send into 3 * 3 fiber couplers through attenuator again, the intrinsic concussion frequency of this bundle light frequency and fiber laser is identical, is called intrinsic laser.The no-load voltage ratio beam splitter is told another Shu Guang of about 90%, " 1 " end input from optical fiber circulator, enter APC ceramic contact pin from the laser of " 2 " end output as the magnetic tape trailer fibre of optic probe, the measurement depth of field of APC ceramic contact pin has several millimeter, and the APC ceramic contact pin by the magnetic tape trailer fibre makes the laser lighting sample.Sample generally is polished into diffuse surface (even be smooth surface, also can become diffuse surface under the shock wave effect), from the irreflexive light beam of tested pilot, collects return laser light by the APC ceramic contact pin again.
After sample was impacted, the laser that is radiated at sample surfaces produced Doppler shift because of the sample surfaces motion makes reflector laser, and promptly carrying movable information becomes flashlight.The reflected light that the APC ceramic contact pin is collected enters optical fiber circulator " 2 " end, by " 3 " end of optical fiber circulator reflected light being sent into fiber amplifier amplifies, send into 3 * 3 fiber couplers and intrinsic laser interference through behind the optical fiber filter again, produce three road light signals of 120 ° of phasic differences, enter photoelectric commutator and become three road electric signal and send into oscillograph recording.Obtain measured surface displacement change procedure in time through signal handler then.
When adopting 3 * 3 fiber couplers of geometric beam-splitting in the all-fiber displacement interference instrument, when two bundle frequencies differentiated light during from the equidirectional two tail optical fibers input of coupling mechanism, produce 120 ° of three road beat signal of phasic difference, this technology can be used for discerning the direction of motion change of testee, mechanism is as follows, and when measured object during towards the instrument test probe movement, the flashlight frequency is higher than intrinsic light, if leading the second tunnel 120 ° of first via signal, Third Road lag behind the second the tunnel 120 °; When measured object instrument when motion dorsad, the flashlight frequency is lower than intrinsic light, the position phase sequence of three road beat signals can be conversely, be the second tunnel 120 ° of first via signal lag, leading the second tunnel 120 ° of Third Road, thereby this working mechanism not only can monitor direction of motion at any time and change, and can improve data processing precision, makes the measuring accuracy of all-fiber displacement interference instrument of the present invention reach nanometer scale.
Can not swing to if confirm the motion of measured object, also can adopt 2 * 2 fiber couplers or 1 * 2 fiber coupler to replace 3 * 3 fiber couplers, produce beat frequency interference, so that reduce development cost.
Adopt optical fiber not only to reduce the end face reflection light of self, promptly reduced background signal, help improving the performance of instrument as popping one's head in; And dwindled the volume of fibre optic interferometer optic probe, help realizing historical measurement of moving displacement of a plurality of points and small sample.
Fiber coupler is used to discern the direction of motion change of measured object.Adopt fiber amplifier amplifying signal light, adopt wave filter to filter the parasitic light of accompaniment signal light; Adopt the adjustable attenuator intrinsic light of suitably decaying, amplifier, wave filter and attenuator Compositional balance system improve signal to noise ratio (S/N ratio).As long as at fibre optic isolater back grafting geometric ratio fiber optic splitter, other element of many cover all-fiber displacement interference instruments that continue again can become the multipath interference instrument system, the motion of a plurality of measuring points on the test target simultaneously.
In all-fiber displacement interference instrument, adopt the adjustable optic fibre attenuator to regulate the intrinsic luminous energy, adopt amplifier amplifying signal luminous energy, the parasitic light that adopts optical fiber filter isolation environment light and loading experiment to produce, adjustable optic fibre attenuator, fiber amplifier, optical fiber filter three consist of a kind of balanced system, make intrinsic light and flashlight energy equal substantially, thereby improve the signal to noise ratio (S/N ratio) of interferometer, improve the contrast of interference signal.
All-fiber displacement interference instrument of the present invention, laser transmits in optical fiber fully, and compact conformation, instrument exempt to transfer, and can realize multi-point sampler easily.The present invention can be used to measure the change in displacement of moving object under a few km per second speed, measures the several millimeters of the depth of field.
Description of drawings
The agent structure synoptic diagram of Fig. 1 compact all optical fiber displacement interferometer of the present invention
Embodiment
As shown in Figure 1, compact all optical fiber displacement interferometer of the present invention, contain fiber laser, fibre optic isolater, no-load voltage ratio beam splitter, optical fiber circulator, adjustable optic fibre attenuator, fiber amplifier, optical fiber filter, fiber coupler and photoelectric commutator, above-mentioned fiber optic element device all connects by single-mode tail fiber.Its annexation is, fiber laser, fibre optic isolater and no-load voltage ratio beam splitter one end are connected successively, no-load voltage ratio beam splitter in addition two ends is connected with optical fiber circulator with the adjustable optic fibre attenuator respectively, and other two ends of optical fiber circulator are respectively with fiber amplifier, be connected as the APC ceramic contact pin of the magnetic tape trailer fibre of optic probe; Fiber amplifier is connected with optical fiber filter, one end of fiber coupler is connected with optical fiber filter with the adjustable optic fibre attenuator respectively, the other end of fiber coupler is connected with an end of photoelectric commutator, and the photoelectric commutator other end is connected with oscillograph in the peripherals.Interferometer and optic probe are made up of optical fiber entirely, the system architecture compactness, and volume is small and exquisite.The fiber coupler that adopts in the interferometer is any one in 3 * 3 fiber couplers, 2 * 2 fiber couplers or 1 * 2 fiber coupler.
In the enforcement, having between the fiber optic element device of tail optical fiber pegs graft by ring flange links to each other.
Compact all optical fiber displacement interferometer is directly to adopt optical fiber as optic probe, and optic probe directly is radiated at the output light-wave of laser instrument on the tested target surface, receives the light wave of target surface reflection simultaneously and transfers to interferometer.
With fiber coupler is that 3 * 3 fiber couplers are example, the laser of fiber laser output, enter the no-load voltage ratio beam splitter through fibre optic isolater, tell small part light (5%～10%) and enter the adjustable optic fibre attenuator, suitably enter 3 * 3 fiber couplers after the decay by the adjustable optic fibre attenuator, this part light frequency is consistent with the frequency of fiber laser output, be called the intrinsic light wave, thereby the adjustable optic fibre attenuator can be adjusted the intensity rate of intrinsic light wave and target surface reflected signal light wave and can obtain high interference signal contrast.Most of laser of telling from the no-load voltage ratio beam splitter enters the optical fiber circulator device, optical fiber circulator with light wave transmissions to optic probe and by the optic probe tested target surface that throws light on.Optic probe is collected diffusing of target surface again and is returned optical fiber circulator, thereby the frequency domain of this part light wave is called as flashlight because of the sample surfaces motion produces Doppler shift.Flashlight passes through wave filter again after fiber amplifier amplifies, filter parasitic light by optical fiber filter, then by entering 3 * 3 fiber couplers behind the adjustable attenuator, with intrinsic light wave beat frequency interference, produce three road beat signals of 120 ° of phasic differences, become three road electric signal through photoelectric commutator again and by oscillograph recording.
Claims (2)
1. compact all optical fiber displacement interferometer is characterized in that: all connect by tail optical fiber between the assembly in the described interferometer, testing laser is transmitted in optical fiber fully; Fiber laser, fibre optic isolater and no-load voltage ratio beam splitter one end are connected successively, no-load voltage ratio beam splitter in addition two ends is connected with optical fiber circulator with the adjustable optic fibre attenuator respectively, and other two ends of optical fiber circulator are respectively with fiber amplifier, be connected as the APC ceramic contact pin of the magnetic tape trailer fibre of optic probe; Fiber amplifier is connected with optical fiber filter, one end of fiber coupler is connected with optical fiber filter with the adjustable optic fibre attenuator respectively, the other end of fiber coupler is connected with an end of photoelectric commutator, and the photoelectric commutator other end is connected with oscillograph in the peripherals;
2. all-fiber displacement interference instrument according to claim 1 is characterized in that: 3 * 3 fiber couplers of splitting ratios such as described fiber coupler employing produce three road beat signals of 120 ° of phasic differences.
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101825435A (en) * | 2010-05-18 | 2010-09-08 | 江苏大学 | All-fiber-optic displacement measuring method and device thereof |
| CN102226683A (en) * | 2011-04-01 | 2011-10-26 | 中国工程物理研究院流体物理研究所 | Light wave microwave secondary frequency mixing system |
| CN102253390A (en) * | 2011-04-19 | 2011-11-23 | 中国工程物理研究院流体物理研究所 | Optical-fiber displacement interferometer |
| CN102419442A (en) * | 2011-09-06 | 2012-04-18 | 中国工程物理研究院流体物理研究所 | Double source laser interference velocity measurement system |
| CN104197844A (en) * | 2014-09-18 | 2014-12-10 | 中国工程物理研究院流体物理研究所 | All optical fiber frequency domain interference absolute distance measurement method and device |
| CN105698674A (en) * | 2016-02-25 | 2016-06-22 | 上海大学 | Integration fiber optic interferometer |
| CN105811235A (en) * | 2014-12-29 | 2016-07-27 | 中国兵器装备研究院 | Multi-spectral modulation module for fiber laser |
| CN107806841A (en) * | 2017-10-20 | 2018-03-16 | 东华大学 | Optical-fiber type homodyne interference system is used in the detection of composite material sealing part surface roughness |
| CN108731597A (en) * | 2018-05-11 | 2018-11-02 | 南京工程学院 | A kind of light path optical-fibre precise displacement sensor altogether |
-
2008
- 2008-09-26 CN CN2008100462024A patent/CN101398294B/en not_active Expired - Fee Related
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101825435A (en) * | 2010-05-18 | 2010-09-08 | 江苏大学 | All-fiber-optic displacement measuring method and device thereof |
| CN102226683A (en) * | 2011-04-01 | 2011-10-26 | 中国工程物理研究院流体物理研究所 | Light wave microwave secondary frequency mixing system |
| CN102253390A (en) * | 2011-04-19 | 2011-11-23 | 中国工程物理研究院流体物理研究所 | Optical-fiber displacement interferometer |
| CN102419442A (en) * | 2011-09-06 | 2012-04-18 | 中国工程物理研究院流体物理研究所 | Double source laser interference velocity measurement system |
| CN104197844A (en) * | 2014-09-18 | 2014-12-10 | 中国工程物理研究院流体物理研究所 | All optical fiber frequency domain interference absolute distance measurement method and device |
| CN104197844B (en) * | 2014-09-18 | 2017-02-22 | 中国工程物理研究院流体物理研究所 | All optical fiber frequency domain interference absolute distance measurement method and device |
| CN105811235A (en) * | 2014-12-29 | 2016-07-27 | 中国兵器装备研究院 | Multi-spectral modulation module for fiber laser |
| CN105698674A (en) * | 2016-02-25 | 2016-06-22 | 上海大学 | Integration fiber optic interferometer |
| CN107806841A (en) * | 2017-10-20 | 2018-03-16 | 东华大学 | Optical-fiber type homodyne interference system is used in the detection of composite material sealing part surface roughness |
| CN108731597A (en) * | 2018-05-11 | 2018-11-02 | 南京工程学院 | A kind of light path optical-fibre precise displacement sensor altogether |
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