CN108983253A - A kind of high-precision laser microspur measurement method - Google Patents
A kind of high-precision laser microspur measurement method Download PDFInfo
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- CN108983253A CN108983253A CN201810854454.3A CN201810854454A CN108983253A CN 108983253 A CN108983253 A CN 108983253A CN 201810854454 A CN201810854454 A CN 201810854454A CN 108983253 A CN108983253 A CN 108983253A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/06—Systems determining position data of a target
- G01S17/08—Systems determining position data of a target for measuring distance only
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
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- Computer Networks & Wireless Communication (AREA)
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- Investigating Or Analysing Materials By Optical Means (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
The invention discloses a kind of high-precision laser microspur measurement methods, with the minor change of distance between the mirror surface of plating reflectance coating and the camera lens with tail optical fiber, it is declined by the lens reflex back into optical fibers with tail optical fiber and swings intracavitary loss and change therewith, the die-away time of pulse signal is caused to change, according to distance between the mirror surface of the specific plating reflectance coating of setting and the camera lens with tail optical fiber and the ring-down time of respective distances is obtained by detection, establish linear relationship curve of the distance with ring-down time, then according to the ring-down time measured and the mirror surface for combining the linear relationship curve of distance and ring-down time to obtain plating reflectance coating to be measured and the distance between the camera lens with tail optical fiber.The present invention has many advantages, such as that high sensitivity, measurement range are wide, it is fast, easy to operate, at low cost to analyze speed and facilitate real-time monitoring, can be used for measuring the slight distance in 1mm or less range.
Description
Technical field
The invention belongs to microspur field of measuring technique, and in particular to a kind of high-precision laser microspur measurement method.
Background technique
With advancing by leaps and bounds for laser technology, precision machinery technology, electronic technology and computer technology, the measurement of laser microspur
Gradually develop to the direction of high speed, high-precision, multi-functional, multi-parameter, small size, it will be in machine vision, automatic processing, work
The fields such as industry on-line checking, control of product quality, profiling in kind, biomedicine have great importance with wide before
Scape is expected to play the role of raising production efficiency and modern production level huge.
In recent years, the research emphasis of micro-displacement measurement is concentrated mainly on both at home and abroad and improves its sensitivity and precision
On.Main microspur measurement method has CCD technology, Moire fringe technology, the interference technique of light, laser ranging technique and reflective
Optical fiber sensing technology etc..The processing of the light pulse signal of the generation and output of the pulse of CCD is very complicated in CCD technology, driving
Pulse is generated by programmable logic controller (PLC), and peripheral circuit is very complicated, is not suitable for applying in small-sized measuring system.Gatestack item
Line measuring technique obtains the mobile displacement of corresponding grating by counting the Moire fringe number moved past, but does not have when data processing
Have and fringe number is finely divided, thus precision is lower, error is larger.The interference technique of light be using to interference fringe counting come real
Now to the measurement of certain physical quantity, however system cost is improved using dual interferometer structure, can not be widely applied.In addition, swashing
The disadvantages of there are system manufacture difficulties for ligh-ranging method greatly, higher cost, cannot be widely used.
Summary of the invention
The present invention be solve in the prior art microspur measuring system structure is complicated, precision is low and it is at high cost the problems such as and provide
A kind of high-precision laser microspur measurement method, this method realize the measurement of laser microspur by fiber optic loop Research on Cavity Ring Down Spectroscopy,
Analysis, study decline swing cavity configuration under micro-displacement change caused by the light decay of optical attenuation swing signal and realize that microspur is accurately surveyed
Amount, this measurement method have that high sensitivity, measurement range are wide, analysis speed is fast, easy to operate, at low cost and facilitate real-time monitoring
The advantages that, it can be used for measuring the slight distance in 1mm or less range.
The present invention adopts the following technical scheme that solve above-mentioned technical problem, a kind of high-precision laser microspur measurement method,
It is characterized by: by passing sequentially through the first connected fiber coupler of optical fiber, 3.6km single mode optical fiber, erbium-doped fiber amplifier, three
Port circulator, the second isolator and the second fiber coupler, which constitute optical fiber and decline, swings chamber, and the first fiber coupler passes sequentially through light
Fibre is connect with the first isolator and laser source, which passes sequentially through route and semiconductor laser modulator and digital signal is sent out
Raw device is connected, and the second fiber coupler is connected by optical fiber with photodetector, which passes through route and oscillograph
It is connected, the isolated port of three port circulators is connected with the camera lens with tail optical fiber, and the mirror surface for plating reflectance coating is placed in the mirror with tail optical fiber
Before head, semiconductor laser modulator, semiconductor laser modulator are accessed when digital signal generator generates a series of impulse waves
Control the output power and wavelength of laser source, it is modulated after optical pulse train via the first isolator and the first fiber coupler
10% port is coupled in optical fiber loop, successively by 3.6km single mode optical fiber, erbium-doped fiber amplifier, three port circulators and
Second isolator is projected by the optical signal that three port circulator input ports input from three port circulator end delivery outlets, is passed through
Optical signal after reflection is returned from three port circulator output ports and is projected from three port circulator isolated ports, and optical fiber, which declines, to be swung
In chamber 90% output light through the second fiber coupler access the first fiber coupler, optical fiber decline swing in chamber 10% output light warp
Second fiber coupler accesses photodetector by optical fiber loop, and the output periodic sequence for the pulse that decays is turned by photodetector
It changes electric signal into, is eventually displayed on digital oscilloscope, with distance between the mirror surface of plating reflectance coating and the camera lens with tail optical fiber
Minor change is declined by the lens reflex back into optical fibers with tail optical fiber and swings intracavitary loss and change therewith, leads to the decaying of pulse signal
Time changes, and is obtained according to distance between the mirror surface of the specific plating reflectance coating of setting and the camera lens with tail optical fiber and by detection
The ring-down time of respective distances establishes linear relationship curve of the distance with ring-down time, then simultaneously according to the ring-down time measured
It is obtained between the mirror surface and camera lens with tail optical fiber of plating reflectance coating to be measured in conjunction with the linear relationship curve of distance and ring-down time
Distance.
Preferably, the erbium-doped fiber amplifier is by the Er-doped fiber of one section of low gain, pump laser and three ports
WDM coupler composition, Er-doped fiber, pump laser and the light pulse of WDM coupler output of low gain are connect respectively in WDM coupling
Three ports of clutch.
Compared with the prior art, the invention has the following beneficial effects:
1, the invention proposes a kind of microspur measurement methods of optical fiber cavity attenuation and vibration technique based on intracavitary amplification, effectively realize
The high-sensitivity measurement of microspur；
2, the present invention is reduced noise in wave distortion and compensated optical fiber ring cavity using low gain low noise Er-doped fiber and declined
Subtract；
3, the present invention increases pulse peak number come compensated optical fiber ring cavity internal loss using erbium-doped fiber amplifier to improve microspur
The precision of measurement；
4, measuring system of the present invention is compact-sized, measurement process is simplified, convenience is rapid, can carry out real-time measurement, and quartz
Optical fiber has many advantages, such as that electromagnetism interference, light-weight, core diameter is slightly easy to process.
Detailed description of the invention
Fig. 1 is the optical path connection figure of microspur measuring system in the present invention.
In figure: 1- digital signal generator, 2- semiconductor laser modulator, 3- laser source, the first isolator of 4-, 5- first
Fiber coupler, 6-3.6km single mode optical fiber, 7- erbium-doped fiber amplifier, tri- port circulator of 8-, camera lens of the 9- with tail optical fiber, 10-
Plate the mirror surface of transmitting film, the second isolator of 11-, the second fiber coupler of 12-, 13- photodetector, 14- oscillograph, 15- light
It is fine.
Specific embodiment
Above content of the invention is described in further details by the following examples, but this should not be interpreted as to this
The range for inventing above-mentioned theme is only limitted to embodiment below, and all technologies realized based on above content of the present invention belong to this hair
Bright range.
Embodiment
A kind of high-precision laser microspur measurement method, by pass sequentially through the first connected fiber coupler 5 of optical fiber 15,
3.6km single mode optical fiber 6, erbium-doped fiber amplifier 7,12 structure of three port circulators 8, the second isolator 11 and the second fiber coupler
It declines at optical fiber and swings chamber, the first fiber coupler 5 passes sequentially through optical fiber 15 and connect with the first isolator 4 and laser source 3, the laser source
3 pass sequentially through route is connected with semiconductor laser modulator 2 and digital signal generator 1, and the second fiber coupler 12 passes through light
Fibre 15 is connected with photodetector 13, which passes through route and be connected with oscillograph 14, three port circulators 8 every
It is connected with the camera lens 9 with tail optical fiber from port, the mirror surface 10 for plating reflectance coating is placed in front of the camera lens 9 with tail optical fiber, wherein er-doped light
Fiber amplifier 7 is made of the WDM coupler of the Er-doped fiber of one section of low gain, pump laser and three ports, and low gain is mixed
The light pulse of erbium optical fiber, pump laser and the output of WDM coupler is connect respectively in three ports of WDM coupler, when number is believed
Number generator 1 generates a series of impulse waves access semiconductor laser modulators 2, and semiconductor laser modulator 2 controls laser source 3
Output power and wavelength, it is modulated after optical pulse train via the first isolator 4 and the first fiber coupler 5 10% port coupling
It closes in optical fiber loop, successively by 3.6km single mode optical fiber 6, erbium-doped fiber amplifier 7, three port circulators 8 and the second isolation
Device 11 is projected by the input optical signal of three port circulators, 8 input port from three port circulators, 8 output port, through reflecting
Optical signal afterwards is returned from three port circulators, 8 output port and is projected from three port circulators, 8 isolated port, and optical fiber, which declines, swings chamber
In 90% output light through the second fiber coupler 12 access the first fiber coupler 5, optical fiber decline swing in chamber 10% output light
Photodetector 13 is accessed by optical fiber loop through the second fiber coupler 12, the output periodic sequence for the pulse that decays is visited by photoelectricity
It surveys device 13 and is converted into electric signal, be eventually displayed on digital oscilloscope 14, decline in optical fiber and swing the second intracavitary isolator 11 and be used for
Ensure signal one-way transmission, light source is avoided to damage, with distance between the mirror surface 10 of plating reflectance coating and the camera lens 9 with tail optical fiber
Minor change, be reflected back optical fiber by the camera lens 9 with tail optical fiber and decline and swing intracavitary loss and change therewith, lead to declining for pulse signal
Subtracting the time changes, and according to distance between the mirror surface 10 of the specific plating reflectance coating of setting and the camera lens 9 with tail optical fiber and passes through inspection
The ring-down time for measuring respective distances establishes linear relationship curve of the distance with ring-down time, is then swung according to declining of measuring
Time and the mirror surface 10 for combining the linear relationship curve of distance and ring-down time to obtain plating reflectance coating to be measured and the camera lens 9 with tail optical fiber
The distance between.
The principle of the present invention is based on fiber optic loop Research on Cavity Ring Down Spectroscopy, a series of impulse waves that digital signal generator generates
Semiconductor laser modulators modulate is transported into pulsed light by " analog-modulated input " port, is entered through the first fiber coupler
Optical fiber loop is declined by optical fiber and swings the intracavitary erbium-doped fiber amplifier of chamber, three port circulators and the second isolator, through plating reflectance coating
Mirror-reflection come out from one end of the second fiber coupler, access photodetector.In order to improve the measurement essence of ring-down time
Degree, it is necessary to increase pulse number.So with an erbium-doped fiber amplifier come the loss of compensated optical fiber loop.Pass through different length
Spend the Amplifier Experiment of Er-doped fiber, Er-doped fiber is too long can generate laser for discovery, and Er-doped fiber is too short, gain not enough, pulse
It is spaced smaller.Therefore, the image intensifer and 980nm pump laser of the Er-doped fiber that length is 2m have been built in laboratory.
Under the same conditions, the decaying spectrum that compared the erbium-doped fiber amplifier (EDFA) for being placed on inside and outside of cavity, when EDFA is put
It sets when intracavitary, the peak strength of pulse signal is bigger, more, is more advantageous to and detects ring-down time.With conventional CRD
Signal processing is compared, and optical fiber, which declines, to be swung the intracavitary system of swinging that declines with EDFA and be greatly improved to the raising of microspur measurement sensitivity.
Temporal analysis is usually to determine fiber optic loop by monitoring the Decay for the light pulse for being introduced into optical fiber circuit
Light loss in road.In FLRDS system, the pulsed light of modulation enters optical fiber loop by the first fiber coupler, then exists
It is repeatedly round-trip in optical fiber loop, in each two-way process, swings a small amount of light of cavity loss since optical fiber declines and can lose, result
It is that light in annular chamber is exponentially decayed at any time, optical cavity ring-down signal may be expressed as:
It=I0exp(-t/τ) (1)
Wherein I0For initial beam intensity, τ is the optical cavity ring-down time.
Damped exponential signals are obtained by the small amount of leakage light of the second coupler every time by photodetector detection record.?
In microspur measurement experiment, optical fiber, which declines, to be swung intracavitary decaying and changes with the variation of distance, when the loss in annular chamber is lower, decaying
Time, τ was bigger.Therefore τ reflects the loss as caused by distance change, and can be obtained by measurement τ.When the decaying of optical cavity
Between τ be defined as the time needed for light decay reduces to the 1/e of its initial strength, which is
In formula, d is the length of optical fiber ring cavity, and c is the light velocity, and n is the refractive index of optical fiber ring cavity, and A is each cavity-type BPM process
In total losses, decline including optical fiber and swing the loss that chamber inherent loss and camera lens are docked with high reflecting mirror surface.It is intracavitary in fiber annular,
The inherent loss of optic fiber ring-shaped cavity is damaged mainly from the scattering of the absorption of optical fiber ring cavity, the insertion loss of fiber coupler, optical fiber
The junction loss of consumption and optical fiber.
The incident light issued by 1550nm light source is entered in optical fiber loop by the first fiber coupler, by Er-doped fiber
Amplifier enters three port circulators, and incident light reflects on the mirror surface of plating reflectance coating, defeated by three port circulator output ports
Out, via the second fiber coupler, it is finally transferred to the variation that reflective light intensity is detected on photodetector, thus measuring band tail optical fiber
Camera lens and plating reflectance coating the distance between mirror surface to get the displacement for arriving reflecting surface.In system the exact value of displacement by
Micrometer control, the camera lens with tail optical fiber are fixed, and micrometer makees the movement perpendicular to sensing direction.
From experiment it can be seen that the light by three port circulator isolated ports is all anti-when tested distance is zero
It is emitted back towards in optical fiber loop, the output intensity of photodetector is maximum at this time, and it is most that declining on oscillograph swings pulse；With band tail optical fiber
Camera lens and plate reflectance coating the distance between mirror surface be gradually increased, the light being reflected back in optical fiber loop is fewer and fewer, photoelectricity visit
It is smaller and smaller to survey device output intensity, declines and swings pulse and also tail off therewith.Therefore, which can be used for the accurate survey of microspur
Amount.
Embodiment above describes basic principles and main features of the invention and advantage, the technical staff of the industry should
Understand, the present invention is not limited to the above embodiments, and the above embodiments and description only describe originals of the invention
Reason, under the range for not departing from the principle of the invention, various changes and improvements may be made to the invention, these changes and improvements are each fallen within
In the scope of protection of the invention.
Claims (2)
1. a kind of high-precision laser microspur measurement method, it is characterised in that: by passing sequentially through the first connected fiber coupling of optical fiber
Device, 3.6km single mode optical fiber, erbium-doped fiber amplifier, three port circulators, the second isolator and the second fiber coupler constitute light
Fibre, which declines, swings chamber, and the first fiber coupler passes sequentially through optical fiber and connect with the first isolator and laser source, which passes sequentially through
Route is connected with semiconductor laser modulator and digital signal generator, and the second fiber coupler passes through optical fiber and photodetector
It is connected, which is connected by route with oscillograph, and the isolated port of three port circulators is connected with the mirror with tail optical fiber
Head, the mirror surface for plating reflectance coating are placed in front of the camera lens with tail optical fiber, when digital signal generator generates a series of impulse wave accesses
Semiconductor laser modulator, the output power and wavelength of semiconductor laser modulator control laser source, it is modulated after light pulse
String is coupled in optical fiber loop via 10% port of the first isolator and the first fiber coupler, successively passes through 3.6km single-mode optics
Fibre, erbium-doped fiber amplifier, three port circulators and the second isolator are believed by the light that three port circulator input ports input
It number is projected from three port circulator end delivery outlets, optical signal after reflection returns from three port circulator output ports and from three
Port circulator isolated port projects, and optical fiber declines the output light for swinging in chamber 90% through the second fiber coupler the first optical fiber coupling of access
Clutch, optical fiber, which declines, to be swung in chamber 10% output light and accesses photodetector by optical fiber loop through the second fiber coupler, and decay pulse
Output periodic sequence electric signal is converted by photodetector, be eventually displayed on digital oscilloscope, with plating reflectance coating
Mirror surface and camera lens with tail optical fiber between distance minor change, declined by the lens reflex back into optical fibers with tail optical fiber and swing intracavitary damage
Consumption changes therewith, and the die-away time of pulse signal is caused to change, according to the mirror surface and magnetic tape trailer of the specific plating reflectance coating of setting
Distance and the ring-down time of respective distances is obtained by detection between fine camera lens, establishes linear relationship of the distance with ring-down time
Then curve obtains plating to be measured according to the ring-down time and the linear relationship curve of combination distance and ring-down time that measure and reflects
The mirror surface of film and the distance between the camera lens with tail optical fiber.
2. high-precision laser microspur measurement method according to claim 1, it is characterised in that: the erbium-doped fiber amplifier
It is made of the WDM coupler of the Er-doped fiber of one section of low gain, pump laser and three ports, Er-doped fiber, the pump of low gain
The light pulse of Pu laser and the output of WDM coupler is connect respectively in three ports of WDM coupler.
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Cited By (3)
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| CN110657749A (en) * | 2019-10-12 | 2020-01-07 | 山东师范大学 | Micro-distance measuring device, method and equipment based on imaging |
| CN114089353A (en) * | 2020-07-31 | 2022-02-25 | 宁波飞芯电子科技有限公司 | Detection system and detection method |
| CN114264238A (en) * | 2021-12-23 | 2022-04-01 | 西南交通大学 | Interferometric displacement measurement system and method based on frequency multiplication principle |
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Application publication date: 20181211 |