CN101509760A - Device and method for measuring position and size of Gaussian beam waist - Google Patents

Abstract

A device and method for measuring the position and size of the beam waist of a Gaussian beam. The device is composed of an optical path device and a circuit device: the device comprises a convex lens group, a multimode optical fiber and a beam splitting sheet which are arranged on an optical fiber coupling frame in sequence along the direction of reference light output by a reference light source, wherein the reference light is divided into transmission light R and reflection light R (f) after passing through the beam splitting sheet; the circuit device comprises a position detector signal processing circuit, a high-voltage amplifying circuit, a triangular wave generating circuit, a +/-15V operational amplifier power supply, an input socket and a computer with a PCI data acquisition board. The invention can greatly reduce the measurement cost and the measurement error.

Description

Measure the device and method of gauss light beam waist position and size

Technical field

The present invention relates to optical measurement, particularly a kind of device and method of measuring gauss light beam waist position and size, it is measured little method of moving to traditional knife-edge method, michelson interferometry and position sensor and combines, and has high precision, advantage cheaply.

Background technology

In cold atom physical study field, thereby light dipole potential well is a kind of monatomic realization on monatomic level the observation of atom and the effective means of controlling of effectively catching.Red off resonance utilizes dipolar forces with the atom limitation of the capturing gauss light beam waist place in the light intensity maximum in the optics dipole potential well of atomic resonance jump frequency, when beam waist during less than 4 μ m, collision blocking effect in the potential well is obvious, and light dipole potential well can easily capture single atom at place with a tight waist.Therefore, in this type of scientific experiment research, accurately locating the beam waist position of the Gaussian beam that produces light dipole potential well and measuring its size is a vital problem.

People such as A.H Firester at article " knife edge scanning method measure sub-wavelength magnitude focused beam " (referring to " Knife-edge scanning measurements of subwavelength focused light beams " Applied Optics, Vol.16, No.7, July 1977, p1971-1974) in, a kind of device is proposed, thereby the piezoelectric ceramics control blade that utilization is driven by the high pressure triangular signal is measured blade in the actual displacement mensuration beam waist size that this side up perpendicular to the precession cutting of tested optical propagation direction and in conjunction with interferometric method, and piezoelectric ceramics control blade the moving on tested optical propagation direction of utilizing another piece driven by the high direct voltage signal located beam waist position.The method that this measurement mechanism is measured beam waist is the gamut repeatability precession of beam cross-section is blocked and by circuit not differentiated by the optical power signals of blade shield portions of detecting to be realized by piezoelectric ceramics control blade, to such an extent as to if the output voltage of the very big high pressure amplifying circuit of beam sizes is difficult to the scanning that the drive pressure electroceramics is done full beam cross section scope, this measuring method can't be used; The method of this measurement mechanism location beam waist position be by change be added in high direct voltage signal on the piezoelectric ceramics amplitude change the transversal displacement amount of blade, since the elongation of piezoelectric ceramics and institute be alive increase into nonlinear relationship, piezoelectric ceramics have lagging characteristics and have when add thereon voltage when constant stroke the creep properties that slowly drifts about takes place, so the degree of accuracy of the method for this location beam waist position is difficult to assurance.Simultaneously, consider also precession under the high pressure triangular signal drives of another piece piezoelectric ceramics when using this method positioning blade lateral attitude, the stability of the package unit of control blade position is difficult to guarantee that the measuring accuracy of beam waist also can be affected.

The beam quality analytical instrument of the precision measurement Gaussian beam parameters of existing domestic and international in the market manufacturer exploitation, but this quasi-instrument costs an arm and a leg mostly, though function is various, but, buy the waste that these type of commodity may cause fund and resource for the scientific experiment and the production that only beam waist and location parameter thereof are had demand.

Summary of the invention

The objective of the invention is at above-mentioned prior art aspect measuring the bearing accuracy of beam waist position, be subject to the shortcoming of sluggishness in the piezoelectric ceramics self performance and non-linear factor, in the shortcoming of the voltage amplification ability of the high pressure amplifying circuit that aspect the measurement capability of light beam transversal size, is limited by the precession of drive pressure electroceramics, and between measurement input cost and measuring accuracy, be difficult to reach unified difficulty, a kind of apparatus and method of measuring gauss light beam waist position and size are provided.This device can reduce greatly to be measured cost and reduces measuring error.

Technical solution of the present invention:

A kind of device of measuring gauss light beam waist position and size is characterized in that this device comprises:

Light path device:

Reference light direction along reference light source output is equipped with convex lens group, frame multimode optical fiber, the beam splitting chip on the optical fiber coupling shelf successively, reference light is divided into transmitted light R (t) and reflected light R (f) through behind the described beam splitting chip, in reflected light R (f) direction first catoptron is arranged, described transmitted light R (t) direction is first set of devices and second set of devices successively, is described beam splitting chip, polaroid, aperture and diode photodetector successively in the reflected light direction of described first catoptron;

The formation of described first set of devices is: second catoptron is fixed on the front end face of columnar piezoelectric ceramics, the rear end face of this piezoelectric ceramics is stained with the ring-shaped pottery sheet and is fixed on the annular base, another side at this annular base is to have externally threaded rear end lens barrel, rear end face at this rear end lens barrel has first plano-convex lens, described second catoptron, piezoelectric ceramics, ring-shaped pottery sheet and the same optical axis of first plano-convex lens, described external thread are fixed on the lens barrel formula two dimension angular adjustment rack; This lens barrel formula two dimension angular adjustment rack is fixed on one can be along regulating on the platform by the photometry working direction with by the manual straight line of two dimension that the vertical direction of photometry working direction is adjusted;

Described second set of devices is an internal connecting type lens barrel, the lens barrel front slot is built-in with second plano-convex lens, lens barrel rear end face center is fixed with position sensor, the lens barrel middle part is an external thread, described second plano-convex lens and the same optical axis of position sensor, described external thread are fixed on the lens barrel formula two dimension angular adjustment rack; This lens barrel formula two dimension angular adjustment rack is fixed on one can be along regulating on the platform by the photometry working direction with by the manual straight line of two dimension that the vertical direction of photometry working direction is adjusted, and this platform has the spiral vernier adjustment knob of micron dimension precision;

Above-mentioned component is fixed on the base plate, and described convex lens group, frame are on the same level height in the horizontal center of two-port, beam splitting chip, first set of devices, second set of devices, polaroid, aperture and the diode photodetector of the multimode optical fiber on the optical fiber coupling shelf;

Blade be fixed on second catoptron on the lateral margin of tested Gaussian beam working direction, the blade of this blade at the another side of this blade, is equipped with photodetector along the tested Gaussian beam direction of propagation laterally perpendicular to tested Gaussian beam;

The transmitted light that described transmitted light R (t) sees through second catoptron of the first set of devices front end arrives described position sensor through second plano-convex lens in the second set of devices entrance pupil behind first plano-convex lens;

Light path between the front surface of the described beam splitting chip and second catoptron constitutes the gage beam of Michelson interferometer, and the light path between the beam splitting chip and first catoptron constitutes the reference arm of Michelson interferometer, and described gage beam equates with the brachium of reference arm;

Circuit arrangement comprises the position sensor signal processing circuit, the high pressure amplifying circuit, circuit for generating triangular wave, ± 15V amplifier power supply, input socket and computing machine with pci data collection plate, the voltage output end of described triangle wave generating circuit is connected to the electric wire input end of the inside surface that is connected to the cylindrical shape piezoelectric ceramics through the high pressure amplifying circuit, two marking current input ends of described position sensor signal processing circuit are connected with the two-way photo-signal output terminal of position sensor, the analog input terminal group of described input socket contact pilotage link group behind respectively with the output terminal of described diode photodetector, the output terminal of photoelectric cell photodetector, the output terminal of circuit for generating triangular wave, the output terminal of position sensor signal processing circuit, the position sensor output terminal links to each other;

Described input socket is connected with the input socket of described computing machine through data line.

Described reference light source is a LASER Light Source.

Described second catoptron is a partially reflecting mirror, and its front surface plating 90% increases anti-film, and 100% anti-reflection film is plated in the rear surface.

Have bar v notch v radially on the described ring-shaped pottery sheet, draw for the electric wire of described piezoelectric ceramics inside surface.

Utilize above-mentioned device to measure the method for gauss light beam waist position and size, comprise the steps:

＜1〉regulate described convex lens group and optical fiber coupling shelf group, optimization enters the beam quality of Michelson interferometer light path;

＜2〉rotatory polarization sheet makes the luminous power through aperture reach maximum, to increase the interference fringe contrast of Michelson interferometer;

＜3〉definition z direction is the working direction of tested Gaussian beam, guarantee tested gauss light beam waist position z〉under 0 the situation, adjust the initial position of first set of devices and make that its z coordinate is 0, and make the Surface Vertical of tested Gaussian beam working direction and described blade, and tested Gaussian beam drops under the blade position near knife edge;

＜4〉start computing machine, utilize the voltage signal U1 of reflection second set of devices of pci data capture card collection position detector signal treatment circuit output with respect to the position of first set of devices, adjust the position of second set of devices according to this signal U1, make the position of first set of devices be in the zone of the signal linear change of position sensor with respect to first set of devices;

＜5〉at the initial position Z of first set of devices ₀=0, choose P complete cycle in the interferometric fringe signal of the reflection blade Michelson interferometer that induced precession changes apart from the sinusoidal form that pass through aperture of u in the equidirectional precession process of single that utilizes the described diode photodetector output that the pci data capture card gathers (p〉1) signal and reach optical power change signal corresponding to the silicon photocell detector of this p complete cycle as the data processing zone, and the normalization optical power signals amplitude of first data point in the data processing zone is designated as m1, the normalization optical power signals amplitude of last data point in the data processing zone is designated as n1, utilizes the displacement u that converses the reality of blade in the equidirectional scanning process of this single of displacement of the blade of complete cycle issue correspondence to be:

$u=p\×\frac{\mathrm{\λ}}{2},$ λ is the reference light wavelength;

As query object, the cumulative function table of query criteria normal function is designated as m2 to the functional value of the cumulative function that finds for the horizontal ordinate of the point of (1-m1) the value of (1-m1); The value of (1-n1) as query object, the cumulative function table of query criteria normal function, the functional value of the cumulative function that finds is designated as n2 for the horizontal ordinate of the point of (1-n1), | n2-m2| is the variable quantity v of the integration variable horizontal ordinate of extrapolating in the described blade moving process from the cumulative function of normalized optical power change correspondence, utilize $\mathrm{\ω}\left(z\right)=\frac{2u}{v}$ Calculate the size ω (z) of the light beam of initial position ₁

＜6〉two dimension of fixing first set of devices by turn manually straight line adjust the horizontal spiral vernier adjustment knob of platform, first set of devices is moved to z axle positive dirction, the distance that moves is the length of a lattice correspondence of minimum scale on the spiral vernier adjustment knob; Reflection second set of devices of signal processing circuit output of utilizing pci data capture card collection position detector is utilized formula with respect to the voltage signal U2 of the position of first set of devices $z=\frac{L}{2}\&times;\frac{U2-\mathrm{<figure-callout\; id="1"\; label="U"\; filenames="A200910048441E00222.png"\; state="\{\{state\}\}">U</figure-callout>}1}{10}\&times;\frac{1}{\frac{2f}{l}-1},$ Determine the distance z of blade with respect to initial position ₁, and z ₁As the lateral attitude coordinate of this position blade,

In the formula: f is the focal length of described first plano-convex lens and second plano-convex lens, l is the vertical range at distance second plano-convex lens convex front surface center on optical axis direction, back plane center of described first plano-convex lens, in this position, choose in the interferometric fringe signal of the reflection blade Michelson interferometer that induced precession changes apart from the sinusoidal form of u in the equidirectional precession process of single that utilizes the diode photodetector output that the pci data capture card collects P complete cycle signal and this p complete cycle correspondence the optical power change signal exported of the silicon photocell detector of utilizing the pci data capture card to collect as data processing object (zone), and the normalization optical power signals amplitude of first data point in the data processing zone is designated as m1, the normalization optical power signals amplitude of last data point in the data processing zone is designated as n1, and the displacement u that utilizes the displacement conversion method of the blade of complete cycle issue correspondence to calculate the reality of blade in the equidirectional scanning process of this single is λ is the reference light wavelength, and as query object, the cumulative function table of query criteria normal function is designated as m2 to the functional value of the cumulative function that finds for the horizontal ordinate of the point of (1-m1) the value of (1-m1); The value of (1-n1) as query object, the cumulative function table of query criteria normal function, the functional value of the cumulative function that finds is designated as n2 for the horizontal ordinate of the point of (1-n1), | n2-m2| is the variable quantity v of the integration variable horizontal ordinate of extrapolating in the described blade moving process from the cumulative function of normalized optical power change correspondence, utilize $\mathrm{\&omega;}\left(z\right)=\frac{2u}{v},$ Bring the value of u and v into, can try to achieve the size ω (z) of the light beam at this blade position place ₂

＜8〉repeating step＜7〉99 times, obtain a series of position z of blade successively ₃To z ₁₀₀, and corresponding ω (z) ₃To ω (z) ₁₀₀

＜9〉compare ω (z) ₁To ω (z) ₁₀₀Value, minimum promptly is the size of beam waist, the position Z of the blade of this size correspondence is position with a tight waist.

Data processing principle of the present invention and method:

(1) computing method of the horizontal displacement of blade:

Definition z direction is the working direction of tested Gaussian beam G, the y direction be tested Gaussian beam G perpendicular to the vertical direction that passes through the beam cross section center in the xsect of the working direction of this light beam, the x direction be in described beam cross-section pass through the beam cross section center and perpendicular to the direction of direction y.

If L is the length of effective photoelectric conversion regions of position sensor, U1 be the reflection blade that utilizes the pci data capture card to collect when being in position 1 on the tested optical propagation direction second set of devices with respect to the output voltage of the position sensor signal processing circuit of the position relation of first set of devices, U2 be the reflection blade that utilizes the pci data capture card to collect when being in position 2 on the tested optical propagation direction second set of devices with respect to the output voltage of the position sensor signal processing circuit of the position relation of first set of devices.By geometric optical theory, two plano-convex lenss identical, that focal length is all f, when these two lens axis coincide and the front focus of the back focus of first plano-convex lens and second plano-convex lens between at a distance of for l the time, the incident light of optical axis of the displacement magnification of the incoming position lens combination that these two plano-convex lenss are formed is parallel to to(for) incident direction is

By the structure of plano-convex lens, the focus that the focal length of its plane one side defines side for this reason on optical axis direction to the distance of the back principal plane of plano-convex lens, and the back principal plane in plano-convex lens and to the distance h of the back plane of plano-convex lens be (

), the focal length of its convex surface one side defines for this reason that focus preceding principal plane to plano-convex lens on optical axis direction of side is the distance at the convex surface center of plano-convex lens, therefore for reaching

Displacement magnification doubly, the back plane of first plano-convex lens should be 2f+l-h to the vertical range at the convex front surface center of second plano-convex lens.Self performance characteristics for position sensor and signal processing circuit thereof, consider the architectural feature of first set of devices of the present invention and second set of devices, and first set of devices takes place laterally to move in actual measurement, second set of devices remains on the constant measuring method of its initial position, especially the relative displacement of the lens combination formed of first plano-convex lens in first set of devices of 2f+l-h and second plano-convex lens in second set of devices amplify relation promptly first set of devices and blade take place laterally when mobile simultaneously, dropping on the distance that the interior luminous point of photoelectric conversion regions of position sensor moves is the horizontal displacement of actual blade

Doubly, therefore if move to the process of position 2 from position 1 at blade, second set of devices changed to U2 with respect to the output voltage of the displacement signal end of the position sensor signal processing circuit of the position relation of first set of devices from U1 when the reflection blade that utilizes the pci data capture card to collect was in certain position on the tested optical propagation direction, and the distance of 2 of position 1 and positions is so:

$z=\frac{L}{2}\&times;\frac{U2-\mathrm{<figure-callout\; id="1"\; label="U"\; filenames="A200910048441E00222.png"\; state="\{\{state\}\}">U</figure-callout>}1}{10}\&times;\frac{1}{\frac{2f}{l}-1}---\left(1\right)$

F is the focal length of described first plano-convex lens and second plano-convex lens in the formula, l is the vertical range at distance second plano-convex lens convex front surface center on optical axis direction, back plane center of described first plano-convex lens, like this, if the measuring error that position sensor moves for the hot spot that drops in its effective photoelectric conversion regions is K μ m, position sensor will be reduced to for the measuring error that blade laterally moves so

(2) the xsect inner light beam size calculation method of Gaussian beam certain position on perpendicular to tested Gaussian beam G working direction

Light distribution is in the xsect at Gaussian beam certain z place, position on perpendicular to the light beam working direction:

$I(x,y)=\frac{2P_0}{{\mathrm{\&pi;\&omega;}}^2\left(z\right)}\exp \left(\frac{-2(x^2+y^2)}{{\mathrm{\&omega;}}^2\left(z\right)}\right)---\left(2\right)$

Wherein: P ₀Be the laser general power, ω (z) is the lateral beam size of this position.

If shelter from segment beam in mode as shown in Figure 6 with blade 8 in the cross section perpendicular to the light beam working direction, then the luminous power of not blocked by blade 8 is:

$P\left(x\right)={\&Integral;}_x^{\&infin;}\mathrm{dx}{\&Integral;}_{-\&infin;}^{\&infin;}\frac{2P_0}{{\mathrm{\&pi;\&omega;}}^2\left(z\right)}\exp \left(\frac{-2(x^2+y^2)}{{\mathrm{\&omega;}}^2\left(z\right)}\right)\mathrm{dy}$

$=\sqrt{\frac{2}{\mathrm{\&pi;}}}\frac{P_0}{\mathrm{\&omega;}\left(z\right)}{\&Integral;}_x^{\&infin;}\exp \left(\frac{-2x^2}{{\mathrm{\&omega;}}^2\left(z\right)}\right)\mathrm{dx}---\left(3\right)$

Wushu (3) normalization:

$P\left(x\right)\&prime;=\frac{P\left(x\right)}{P_0}=\sqrt{\frac{2}{\mathrm{\&pi;}}}\frac{1}{\mathrm{\&omega;}\left(z\right)}{\&Integral;}_x^{\&infin;}\exp \left(\frac{-2x^2}{{\mathrm{\&omega;}}^2\left(z\right)}\right)\mathrm{dx}---\left(4\right)$

Order $t=\frac{2x}{\mathrm{\&omega;}\left(z\right)},$ Bring into after formula (3) does substitution of variable, have:

$P\left(t\right)\&prime;=\frac{1}{\sqrt{2\mathrm{\&pi;}}}{\&Integral;}_x^{\&infin;}\exp (-\frac{t^2}{2})\mathrm{dt}$

$=1-\frac{1}{\sqrt{2\mathrm{\&pi;}}}{\&Integral;}_{-\&infin;}^x\exp (-\frac{t^2}{2})\mathrm{dt}---\left(5\right)$

Be not difficult to find that last is the cumulative function of standardized normal distribution for formula (5) the right.Therefore, can connect the luminous power that sees through behind the blade 8 with the variation relation of blade position displacement and the cumulative function of standardized normal distribution by substitution of variable.If u is blade displacement in the equidirectional scanning process of certain single in perpendicular to light beam working direction cross section, v is the variable quantity of the integration variable horizontal ordinate extrapolated from the cumulative function of normalized optical power change correspondence in the blade precession process.Then the lateral dimension ω (z) at z place, this position light beam is:

$\mathrm{\&omega;}\left(z\right)=\frac{2u}{v}---\left(6\right)$

Actual vertical moving distance (with respect to tested Gaussian beam working direction) u of blade 8 can determine apart from moving period's number of the interference signal of the Michelson interferometer of the sinusoidal form variation of u by the reaction blade 8 that passes through aperture induced precession in the equidirectional precession process of single that the diode photodetector that calculating utilizes the pci data capture card to collect in the blade moving process is exported: if this signal has moved p cycle in this process, be that interference fringe whenever moves one according to principle of interference then, the relative length between two corresponding interference arms changes size and is

So the distance that blade moves is $u=\frac{\mathrm{\&lambda;}}{2}\&times;p,$ Wherein λ is the reference light wavelength.

The computing method of the variable quantity v of the integration variable horizontal ordinate of extrapolating from the cumulative function of normalized optical power change correspondence in the blade moving process are:

The part of getting in the optical power change signal of the silicon photocell detector output of the luminous power size of the part that the tested Gaussian beam G of reflection that utilizes the pci data capture card to collect from the equidirectional precession scanning process of certain single of blade is not blocked by blade in this signal corresponding to p complete cycle in the interference signal of the Michelson's interferometer of the sinusoidal form variation of pass through aperture of the diode photodetector output that utilizes the pci data capture card to collect in this blade moving process is the data processing area territory. The optical power change signal of the silicon photocell detector output that collects is done normalized.The normalization optical power signals amplitude of first data point in the data processing zone is designated as m1, the normalization optical power signals amplitude of last data point in the data processing zone is designated as n1.As query object, the cumulative function table of query criteria normal function, the functional value that finds cumulative function are that the horizontal ordinate of the point of (1-m1) is designated as m2 (1-m1); As query object; The cumulative function table of query criteria normal function, the functional value that finds cumulative function are that the horizontal ordinate of the point of (1-n1) is designated as n2 (1-n1) .| m2-n2| is the variable quantity v of the integration variable horizontal ordinate of extrapolating in the described blade precession process from the cumulative function of normalized optical power change correspondence.

So far, can calculate the light beam transversal size that this blade lateral attitude goes out easily by formula (6).And, through measuring and calculating, because the irrelevance that the optical power signals that the silicon photocell photodetector that blade causes for tested diffraction of light detects departs from standardized normal distribution less than 5%, is therefore thought and still can be calculated the light beam transversal size by the query criteria gaussian distribution table.

In addition, find out easily, even the scope in the data processing zone of being got less than the scope of light beam entire cross section, also can use described computing method to calculate the light beam transversal size easily.Therefore, described method is with regard to having avoided prior art and must covering whole beam cross-section scope to the measurement of beam cross-section and be limited by the problem of the enlargement factor of high pressure amplifying circuit.

(3) definite method beam waist and beam waist position

The z coordinate of guaranteeing tested gauss light beam waist position is determined the initial position of a blade greater than under 0 the situation, makes that its z coordinate is 0.In initial position, by interference signal to the Michelson interferometer of the sinusoidal form variation of pass through aperture that utilizes the diode photodetector output that the pci data capture card collects, the optical power change signal that the silicon photocell detector of the luminous power size of the part that the tested Gaussian beam G of the reflection that utilizes the pci data capture card to collect is not blocked by blade detects, utilize reflection second set of devices of signal processing circuit output of the position sensor of pci data capture card collection to carry out data processing, determine the beam sizes w at this blade position place with respect to the voltage signal of the position of first set of devices ₁The two dimension of fixing first set of devices by the turn manually horizontal spiral vernier adjustment knob regulated on the platform of straight line makes first set of devices move to the positive dirction of z axle, and distance is the length of a lattice correspondence of minimum scale on the spiral vernier adjustment knob.According to the lateral attitude of described method repeatability moving blade 100 times, and calculate the distance z of this position with respect to initial position at each blade position place ₁To z ₁₀₀And corresponding beam sizes w ₁To w ₁₀₀Compare w ₁To w ₁₀₀, minimum promptly is the size of beam waist, the blade position Z of this size correspondence is beam waist position.

The invention has the beneficial effects as follows, can make things convenient for, accurately, simultaneously the beam waist of Gaussian beam and position thereof are measured at low cost and are located.

Description of drawings

Fig. 1 is the light path synoptic diagram of the light path device of the embodiment of the invention

Fig. 2 is the structural representation of first set of devices (6) of the light path device of the embodiment of the invention

Fig. 3 is the structural representation of second set of devices (7) of the light path device of the embodiment of the invention

Fig. 4 is the schematic appearance of thin ring-shaped pottery sheet (15) in first set of devices (6) of light path device of the embodiment of the invention

Fig. 5 is a circuit arrangement annexation synoptic diagram of the present invention

Fig. 6 is the shielding mode synoptic diagram of blade of the present invention (8) to tested Gaussian beam xsect

Embodiment

The invention will be further described below in conjunction with embodiment and accompanying drawing, but should not limit protection scope of the present invention with this.

See also Fig. 1 to Fig. 5, as seen from the figure, the present invention measures the device of gauss light beam waist position and size, comprising:

Light path device:

Reference light R direction along reference light source output is equipped with convex lens group 1, frame multimode optical fiber 3 and the beam splitting chip 4 on optical fiber coupling shelf 2 successively, reference light R is divided into transmitted light R (t) and reflected light R (f) through behind the described beam splitting chip 4, in reflected light R (f) direction first catoptron 5 is arranged, described transmitted light R (t) direction is first set of devices 6 and second set of devices 7 successively, is described beam splitting chip 4, polaroid 10, aperture 11 and diode photodetector 12 successively in the reflected light direction of described first catoptron 5;

The formation of described first set of devices 6 is: second catoptron 13 is fixed on the front end face of columnar piezoelectric ceramics 14, the rear end face of this piezoelectric ceramics 14 is stained with ring-shaped pottery sheet 15 and is fixed on the annular base 16, another side at this annular base 16 is the rear end lens barrel 18 with external thread 17, rear end face at this rear end lens barrel 18 has first plano-convex lens 19, described second catoptron 13, piezoelectric ceramics 14, ring-shaped pottery sheet 15 and first plano-convex lens, 19 same optical axises, described external thread 17 are fixed on the lens barrel formula two dimension angular adjustment rack (not shown); This lens barrel formula two dimension angular adjustment rack is fixed on one can be along regulating on the platform by the photometry working direction with by the manual straight line of two dimension that the vertical direction of photometry working direction is adjusted;

Described second set of devices 7 is an internal connecting type lens barrel, the lens barrel front slot is built-in with second plano-convex lens 20, lens barrel rear end face center is fixed with position sensor 22, the lens barrel middle part is an external thread 21, described second plano-convex lens 19 and position sensor 21 same optical axises, described external thread 21 are fixed on the lens barrel formula two dimension angular adjustment rack (not shown); This lens barrel formula two dimension angular adjustment rack is fixed on one can be along regulating on the platform by the photometry working direction with by the manual straight line of two dimension that the vertical direction of photometry working direction is adjusted, and this platform has the spiral vernier adjustment knob of micron dimension precision;

Above-mentioned component is fixed on the base plate, and described convex lens group 1, frame are on the same level height in the horizontal center of two-port, beam splitting chip 4, first set of devices 6, second set of devices 7, polaroid 10, aperture 11 and the diode photodetector 12 of the multimode optical fiber on the optical fiber coupling shelf 23;

A blade 8 is fixed on second catoptron 13) on the lateral margin of tested Gaussian beam G working direction, the blade of this blade 8 at the another side of this blade 8, is equipped with photodetector 9 along the tested Gaussian beam G direction of propagation laterally perpendicular to tested Gaussian beam G;

The transmitted light that described transmitted light R (t) sees through second catoptron 13 of first set of devices, 6 front ends arrives described position sensor 22 through second plano-convex lens 20 in second set of devices, 7 entrance pupils behind first plano-convex lens 19;

Light path between the front surface of the described beam splitting chip 4 and second catoptron 13 constitutes the gage beam of Michelson interferometer, light path between the beam splitting chip 4 and first catoptron 5 constitutes the reference arm of Michelson interferometer, and described gage beam equates with the brachium of reference arm;

Circuit arrangement comprises: position sensor signal processing circuit 23, high pressure amplifying circuit 24, circuit for generating triangular wave 25, ± 15V amplifier power supply 26, input socket 27 and computing machine 29 with pci data collection plate 28, the voltage output end 31 of described triangle wave generating circuit 25 is connected to the electric wire input end 24 of the inside surface that is connected to cylindrical shape piezoelectric ceramics 14 through high pressure amplifying circuit 24, two marking current input ends 35 of described position sensor signal processing circuit 23,36 with the two-way photo-signal output terminal 37 of position sensor 14,38 are connected, the analog input terminal group of described input socket 27 contact pilotage link group 39 behind respectively with the output terminal 39 of described diode photodetector 12, the output terminal 40 of photodetector 9, the output terminal 31 of circuit for generating triangular wave 25, position sensor signal processing circuit 2) output terminal 30, position sensor 22 output terminals 37,38 link to each other;

Described input socket 27 is connected with the input socket 41 of described computing machine 29 through data line.

In the present embodiment, reference light R is divided into two-beam through behind the beam splitting chip 4---transmitted light R (t) and reflected light R (f), R (f) arrives first completely reflecting mirror, 5 backs and reflects along original optical path, the 20 ° of catoptron 13 backs that transmitted light R (t) arrives first set of devices, 6 front ends are divided into reflected light and transmitted light two parts on its surface, the R of reflected back (t) light returns along original optical path, and cross at beam splitting chip 4 places and outgoing with R (f) light of reflected back, on the working direction of this emergent light F, be equipped with polaroid 10 successively, 40 μ m aperture aperture 11 and diode photodetectors 12, arrive the photoelectric conversion regions of one dimension position sensors 22 behind the one 6.4mm focal length plano-convex lens 19 of the afterbody of the R of transmission (t) by first set of devices, 6 rear end lens barrels 18 through the 2nd 6.4mm focal length plano-convex lenss 20 in second set of devices 7, the 20 ° of catoptron 13 of first set of devices, 6 front ends is fixed on the preceding annular end face of cylindrical shape piezoelectric ceramics 14, the back annular end face of piezoelectric ceramics 14 is fixed on the thin annular base 16 after being stained with thin ring-shaped pottery sheet 15, blade 8 be fixed in second catoptron 13 towards by on the lateral margin of photometry working direction, a proceeds posterolateral 1.5mm place of the tested dorsad Gaussian beam G of blade 8 direction of propagation is equipped with silicon photocell photodetector 9; The voltage output end 31 of the triangle wave generating circuit 25 in the circuit part device of the present invention is connected to the voltage input end 32 of high pressure amplifying circuit 24, the voltage output end 33 of high pressure amplifying circuit 24 is connected to the electric wire input end 24 of the inside surface that is connected to the hollow cylinder piezoelectric ceramics, two marking current input ends 35 of position sensor signal processing circuit 23,36 with the two-way photo-signal output terminal 37 of position sensor, 38 are connected, and the analog input terminal group of circuit part input socket 27 contact pilotage link group 39 behind is connected to the output signal end 39 of diode photodetector 12, the output signal end 40 of photoelectric cell photodetector 9, the output signal end 31 of circuit for generating triangular wave 25, the displacement signal output terminal 30 of position sensor signal processing circuit 23, the first via output current signal end 37 of position sensor 22, the second road output current signal end 38 of position sensor 22.

Described convex lens group 1 contains two 2cm focal length convex lens, and using this lens combination purpose is to make implementation pattern coupling between the reference light of input and multimode optical fiber.

Described second set of devices 7 keeps its initial position constant in measuring process.

Described reference light source R can select LASER Light Source commonly used arbitrarily, as He-Ne Lasers light source, semiconductor laser light resource.

The described luminous power that incides the reference light source R on the beam splitting chip 4 is not less than 0.4mW, be not higher than 4mW so that fall luminous power in the photoelectric conversion regions of position sensor 22 through the photocurrent size after the opto-electronic conversion in position detector signal treatment circuit 23 has the input photocurrent magnitude range of response.

The luminous power splitting ratio of described beam splitting chip 4 is transmitted optical power: reflected optical power=1:1.

The front surface plating 90% of described second catoptron 13 increases anti-film, and 100% anti-reflection film is plated in the rear surface.

The external thread screw socket 17 of described first set of devices 6 through connecing thereafter is fixed on the common lens barrel formula two dimension angular adjustment rack; Common lens barrel formula two dimension angular adjustment rack is fixed on one can be along regulating on the platform by the photometry working direction with by the manual straight line of two dimension that the vertical direction of photometry working direction is adjusted, the degree of regulation of two spiral vernier adjustment knobs of this platform is regulated the position of these two knob scalable blades 8 with respect to tested Gaussian beam in micron dimension.

Described second set of devices 7 is an internal connecting type lens barrel, optical tube length is 420mm, the lens barrel front slot is built-in with the 2nd 6.4mm focal length plano-convex lens 20, lens barrel afterbody circular end surface center is fixed with position sensor 22, below, lens barrel tail end face position sensor 22 present positions has aperture, conveniently to draw the electric wire that is connected to position sensor.

Described second set of devices 7 is fixed on the common lens barrel formula two dimension angular adjustment rack through the external thread screw socket 21 at lens barrel middle part; Common lens barrel formula two dimension angular adjustment rack is fixed on one can be along regulating on the platform by the photometry working direction with by the manual straight line of two dimension that the vertical direction of photometry working direction is adjusted, the degree of regulation of two spiral vernier adjustment knobs of this platform is regulated the position of this two knob scalable, second set of devices 7 with respect to first set of devices 6 in micron dimension.

The external diameter of the external thread 21 of described second set of devices 7 equals the internal diameter of the lens barrel connecting thread of common lens barrel formula two dimension angular adjustment rack, and the external diameter of actual lens barrel part is less than 21 mouthfuls of external diameters of external thread spiral shell.

A described 6.4mm focal length plano-convex lens 19, the 2nd 6.4mm focal length plano-convex lens 20 are convex surface towards the reference light direction of propagation, and the plane of two lens is parallel to each other.

In the heart vertical range l is 10.2mm in the convex front surface 20 of the back plane center of a described 6.4mm focal length plano-convex lens 19 and the 2nd 6.4mm focal length plano-convex lens.

The thin annular base 16 of described first set of devices 6, external thread 17, after connect lens barrel 18 and be the structure of one, the external diameter of external thread 17 equals the internal diameter of the lens barrel connecting thread of common lens barrel formula two dimension angular adjustment rack, also equal the external diameter of thin annular base 16, the external diameter of actual lens barrel part 18 is less than external thread screw socket 17 external diameters, and the internal diameter of thin annular base 16 equals to connect thereafter the internal diameter of lens barrel 18, external diameter less than piezoelectric ceramics 14, the external diameter of thin annular base 16 is greater than the external diameter of piezoelectric ceramics 14, so that external diameter can be fixed together with common lens barrel formula two dimension angular adjustment rack less than the piezoelectric ceramics 14 of the lens barrel connecting thread internal diameter of common lens barrel formula two dimension angular adjustment rack.

Have as shown in Figure 5 bar v notch v radially on the described thin ring-shaped pottery sheet 15, to play insulating effect, thereafter common lens barrel formula two dimension angular adjustment rack is charged when preventing to increase piezoelectricity on the piezoelectric ceramics 14 in measuring process.

The described electric wire input end 34 that is connected to piezoelectric ceramics 14 inside surfaces is drawn from the bar v notch v radially that thin ring-shaped pottery sheet 15 has.

A described 6.4mm focal length plano-convex lens 19, the 2nd thickness r of 6.4mm focal length plano-convex lens 20 on optical axis direction are 5.381mm.

The optical element of described light path part device of the present invention is fixed in through respective seat and is of a size of on the high-quality aviation aluminium material optical flat that length x width x thickness is 250 * 400 * 12mm, be covered with metric system M6 screw on this optical flat, the line-spacing of screw * row distance is 25 * 25mm.

Described data acquisition board 28 is directly inserted the PCI slot in the computer host box 29, the circuit part input socket of installing in circuit part device of the present invention 27 is connected to the input socket end 41 of PCI slot on computer host box 29 backboards through data line, start computing machine 29, after the supporting application program of installation data capture card 28 on the computing machine 29, promptly can read each the road signal that collects, handle thereby carry out related data.

The frequency of described circuit for generating triangular wave 25 output symmetries is the triangular signal of 1Hz, after this signal is connected to the signal input part 32 of high pressure amplifying circuit 24, the triangular signal that has amplified by one of output terminal 33 output of high pressure amplifying circuit 24, import described piezoelectric ceramics 14 inside surfaces, so that closely at the uniform velocity precession of front and back repeatedly takes place for piezoelectric ceramics 14 and blade 8 fixed thereon, thereby the repeatability that realizes 8 pairs of tested Gaussian beam xsects of blade is closely at the uniform velocity blocked.

Described position sensor 22 can require to change the device of different model according to measuring accuracy, and what adopt in the present embodiment is the product one dimension position sensitive detector of Japanese Hamamatsu Photonics K. K, and product type is S4581-04.

Use measurement device Gaussian beam of the present invention to measure the method for gauss light beam waist position and size, comprise the steps:

＜1〉regulate described convex lens group 1 and optical fiber coupling shelf group 2, reference beam R implemented the optical fiber coupling operation, purpose be make enter the Michelson interferometer light path beam quality reach optimization;

＜2〉the rotatory polarization sheet 10, make the luminous power through aperture 11 reach maximum, to increase the interference fringe contrast of Michelson interferometer;

＜3〉definition z direction is the working direction of tested Gaussian beam G, the y direction be tested Gaussian beam G perpendicular to the vertical direction that passes through the beam cross section center in the xsect of the working direction of this light beam, the x direction be in described beam cross-section pass through the beam cross section center and perpendicular to the direction of direction y.Guarantee tested gauss light beam waist position z〉under 0 the situation, adjust the initial position of first set of devices 6, make that its z coordinate is 0, and make tested Gaussian beam working direction and described blade 8 Surface Vertical, and tested Gaussian beam G drops on that luminous point on the blade 8 is in blade 8 middle and lower parts and near the position of knife edge;

＜4〉start computing machine, utilize pci data capture card 28 collection position detector signal treatment circuits 3) reflection second set of devices 7 of displacement signal output terminal 30 output with respect to the voltage signal U1 of the position of first set of devices 6, adjust the position of second set of devices 7 according to this signal U1, make size that the position of the set of devices 6 of winning is in signal U1 move the zone that is the linear changing relation with the linearity of the second set of devices position with respect to first set of devices 6;

＜5〉in the initial position of first set of devices 6, choose p complete cycle in the interferometric fringe signal that utilizes reflection blade 8 that pci data capture card 28 the gathers described diode photodetector 12 outputs Michelson interferometer that induced precession changes apart from the sinusoidal form that pass through aperture 11 of u in the equidirectional precession process of single (p〉2 positive integer) signal and reach the optical power change signal that utilizes pci data capture card 28 collection silicon photocell detector 9 corresponding to this p complete cycle as the data processing zone, and the normalization optical power signals amplitude of first data point in the data processing zone is designated as m1, the normalization optical power signals amplitude of last data point in the data processing zone is designated as n1, utilizes the displacement u that converses the reality of blade 8 in the equidirectional scanning process of this single of displacement of the blade (8) of complete cycle issue correspondence to be:

$u=p\&times;\frac{\mathrm{\&lambda;}}{2},$ λ is the reference light wavelength;

As query object, the cumulative function table of query criteria normal function is designated as m2 to the functional value of the cumulative function that finds for the horizontal ordinate of the point of (1-m1) the value of (1-m1); The value of (1-n1) as query object, the cumulative function table of query criteria normal function, the functional value of the cumulative function that finds is designated as n2 for the horizontal ordinate of the point of (1-n1), | n2-m2| is the variable quantity v of the integration variable horizontal ordinate of extrapolating in described blade 8 moving process from the cumulative function of normalized optical power change correspondence, utilize $\mathrm{\&omega;}\left(z\right)=\frac{2u}{v}$ Calculate the beam waist w of initial position ₁

＜6〉two dimension that is fixed with first set of devices 6 by turn manually the straight line horizontal spiral vernier adjustment knob of adjusting platform first set of devices 6 is moved to z axle positive dirction position, distance is the length of a lattice correspondence of minimum scale on the spiral vernier adjustment knob; Utilize the voltage signal U2 of reflection second set of devices 7 of pci data capture card 28 collection position detector signal treatment circuits 23 outputs, according to formula with respect to the position of first set of devices 6 $z=\frac{L}{2}\&times;\frac{U2-U1}{10}\&times;\frac{1}{\frac{2f}{l}-1}$ Determine the distance z of blade 8 with respect to initial position ₁, and z ₁Lateral attitude coordinate as this position blade 8, f is the focal length of described first plano-convex lens 19 and second plano-convex lens 20 in the formula, and l is the vertical range at distance second plano-convex lens (20) convex front surface center on optical axis direction, back plane center of described first plano-convex lens 19.In this position, in the interferometric fringe signal of the reflection blade 8 of choosing output terminal 39 outputs that utilize the diode photodetector 12 that pci data capture card 28 the collects Michelson interferometer that induced precession changes apart from the sinusoidal form of u in the equidirectional precession process of single several complete cycles (establishing the complete cycle issue is p) signal and this p complete cycle correspondence the optical power change signal exported of the output terminal (40) that utilizes the silicon photocell detector (9) that pci data capture card (28) collects as data processing object (zone), and the normalization optical power signals amplitude of first data point in the data processing zone is designated as m1, the normalization optical power signals amplitude of last data point in the data processing zone is designated as n1.The displacement u that utilizes the displacement conversion method of the blade 8 of complete cycle issue correspondence to calculate the reality of blade 8 in the equidirectional scanning process of this single is

λ is the reference light wavelength, and as query object, the cumulative function table of query criteria normal function is designated as m2 to the functional value of the cumulative function that finds for the horizontal ordinate of the point of (1-m1) the value of (1-m1); The value of (1-n1) as query object, the cumulative function table of query criteria normal function, the functional value of the cumulative function that finds is designated as n2 for the horizontal ordinate of the point of (1-n1), | n2-m2| is the variable quantity v of the integration variable horizontal ordinate of extrapolating in described blade 8 moving process from the cumulative function of normalized optical power change correspondence, utilize $\mathrm{\&omega;}\left(z\right)=\frac{2u}{v},$ Bring the value of u and v into, can try to achieve the beam waist w at this blade position place ₂

＜8〉repeating step＜7〉99 times, obtain z successively ₂To z ₁₀₀, and corresponding w ₂To w ₁₀₀

＜9〉compare w ₁To w ₁₀₀Value, minimum promptly is the size of beam waist, the position Z of the blade 8 of this size correspondence is position with a tight waist;

Adopt device and method of the present invention that the focus gauss light beam of one known waist spot size is measured, the measuring error of beam waist is ± 0.2 μ m, the positioning error of beam waist position is ± 0.85 μ m～± 1.69 μ m, and this proves absolutely the high measurement accuracy of device and method of the present invention.

Claims (5)

1, a kind of device of measuring gauss light beam waist position and size is characterized in that this device comprises:

Light path device:

Reference light (R) direction along reference light source output is equipped with convex lens group (1) successively, multimode optical fiber (3) and the beam splitting chip (4) of frame on optical fiber coupling shelf (2), be divided into transmitted light R (t) and reflected light R (f) behind reference light (R) the described beam splitting chip of process (4), in reflected light R (f) direction first catoptron (5) is arranged, described transmitted light R (t) direction is first set of devices (6) and second set of devices (7) successively, is described beam splitting chip (4) successively in the reflected light direction of described first catoptron (5), polaroid (10), aperture (11) and diode photodetector (12);

The formation of described first set of devices (6) is: second catoptron (13) is fixed on the front end face of columnar piezoelectric ceramics (14), the rear end face of this piezoelectric ceramics (14) is stained with ring-shaped pottery sheet (15) and is fixed on the annular base (16), another side at this annular base (16) is the rear end lens barrel (18) with external thread (17), rear end face at this rear end lens barrel (18) has first plano-convex lens (19), described second catoptron (13), piezoelectric ceramics (14), ring-shaped pottery sheet (15) and the same optical axis of first plano-convex lens (19), described external thread (17) are fixed on the lens barrel formula two dimension angular adjustment rack; This lens barrel formula two dimension angular adjustment rack is fixed on one can be along regulating on the platform by the photometry working direction with by the manual straight line of two dimension that the vertical direction of photometry working direction is adjusted;

Described second set of devices (7) is an internal connecting type lens barrel, the lens barrel front slot is built-in with second plano-convex lens (20), lens barrel rear end face center is fixed with position sensor (22), the lens barrel middle part is external thread (21), described second plano-convex lens (19) and the same optical axis of position sensor (21), described external thread (21) are fixed on the lens barrel formula two dimension angular adjustment rack; This lens barrel formula two dimension angular adjustment rack is fixed on one can be along regulating on the platform by the photometry working direction with by the manual straight line of two dimension that the vertical direction of photometry working direction is adjusted, and this platform has the spiral vernier adjustment knob of micron dimension precision;

Above-mentioned component is fixed on the base plate, and the horizontal center of two-port, beam splitting chip (4), first set of devices (6), second set of devices (7), polaroid (10), aperture (11) and the diode photodetector (12) of described convex lens group (1), the frame multimode optical fiber (3) on optical fiber coupling shelf (2) is on the same level height;

A blade (8) be fixed on second catoptron (13) on the lateral margin of tested Gaussian beam (G) working direction, the blade of this blade (8) is laterally perpendicular to tested Gaussian beam (G), another side in this blade (8) is equipped with photodetector (9) along tested Gaussian beam (G) direction of propagation;

The transmitted light that described transmitted light R (t) sees through second catoptron (13) of first set of devices (6) front end arrives described position sensor (22) through second plano-convex lens (20) in second set of devices (7) entrance pupil behind first plano-convex lens (19);

Light path between the front surface of described beam splitting chip (4) and second catoptron (13) constitutes the gage beam of Michelson interferometer, light path between beam splitting chip (4) and first catoptron (5) constitutes the reference arm of Michelson interferometer, and described gage beam equates with the brachium of reference arm;

Circuit arrangement comprises: position sensor signal processing circuit (23), high pressure amplifying circuit (24), circuit for generating triangular wave (25), ± 15V amplifier power supply (26)/input socket (27) and have the computing machine (29) of pci data collection plate (28), the voltage output end (31) of described triangle wave generating circuit (25) is connected to the electric wire input end (24) of the inside surface that is connected to cylindrical shape piezoelectric ceramics (14) through high pressure amplifying circuit (24), two marking current input ends (35) (36) of described position sensor signal processing circuit (23) are connected with the two-way photo-signal output terminal (37) (38) of position sensor (14), the analog input terminal group of described input socket (27) contact pilotage link group (39) behind respectively with the output terminal (39) of described diode photodetector (12), the output terminal (40) of photoelectric cell photodetector (9), the output terminal (31) of circuit for generating triangular wave (25), the output terminal (30) of position sensor signal processing circuit (23), position sensor (22) output terminal (37) (38) links to each other;

Described input socket (27) is connected with the input socket (41) of described computing machine (29) through data line.

2, the device of mensuration gauss light beam waist position according to claim 1 and size is characterized in that described reference light source is a LASER Light Source.

3, the device of mensuration gauss light beam waist position according to claim 1 and size is characterized in that described second catoptron is a partially reflecting mirror, and its front surface plating 90% increases anti-film, and 100% anti-reflection film is plated in the rear surface.

4, the device of mensuration gauss light beam waist position according to claim 1 and size is characterized in that having on the described ring-shaped pottery sheet (15) bar v notch v radially, draws for the electric wire of described piezoelectric ceramics (14) inside surface.

5, utilize the described device of claim 1 to measure the method for gauss light beam waist position and size, it is characterized in that comprising the steps:

＜1〉regulate described convex lens group (1) and optical fiber coupling shelf group (2), optimization enters the beam quality of Michelson interferometer light path;

＜2〉rotatory polarization sheet (10) makes the luminous power through aperture (11) reach maximum, to increase the interference fringe contrast of Michelson interferometer;

＜3〉definition z direction is the working direction of tested Gaussian beam G, guarantee tested gauss light beam waist position z〉under 0 the situation, adjust the initial position of first set of devices (6) and make that its z coordinate is 0, and make the Surface Vertical of tested Gaussian beam working direction and described blade (8), and tested Gaussian beam (G) drops under the blade (8) position near knife edge;

＜4〉start computing machine, utilize the voltage signal U1 of reflection second set of devices (7) of pci data capture card (28) collection position detector signal treatment circuit (23) output terminal (30) output with respect to the position of first set of devices (6), adjust the position of second set of devices (7) according to this signal U1, make the position of first set of devices (6) be in the zone of the signal linear change of position sensor (22) with respect to first set of devices (6);

＜5〉at the initial position Z of first set of devices (6) ₀=0, choose P complete cycle in the interferometric fringe signal of reflection blade (8) Michelson interferometer that induced precession changes apart from the sinusoidal form that pass through aperture (11) of u in the equidirectional precession process of single that utilizes described diode photodetector (12) output that pci data capture card (28) gathers (p〉1) signal and reach optical power change signal corresponding to this p silicon photocell detector of a complete cycle (9) as the data processing zone, and the normalization optical power signals amplitude of first data point in the data processing zone is designated as m1, the normalization optical power signals amplitude of last data point in the data processing zone is designated as n1, utilizes the displacement u that converses the reality of blade (8) in the equidirectional scanning process of this single of displacement of the blade (8) of complete cycle issue correspondence to be:

$u=p\&times;\frac{\mathrm{\&lambda;}}{2},$ λ is the reference light wavelength;

As query object, the cumulative function table of query criteria normal function is designated as m2 to the functional value of the cumulative function that finds for the horizontal ordinate of the point of (1-m1) the value of (1-m1); The value of (1-n1) as query object, the cumulative function table of query criteria normal function, the functional value of the cumulative function that finds is designated as n2 for the horizontal ordinate of the point of (1-n1), | n2-m2| is the variable quantity v of the integration variable horizontal ordinate of extrapolating in described blade (8) moving process from the cumulative function of normalized optical power change correspondence, utilize $\mathrm{\&omega;}\left(z\right)=\frac{2u}{v}$ Calculate the size ω (z) of the light beam of initial position ₁

＜6〉two dimension of fixing first set of devices (6) by turn manually straight line adjust the horizontal spiral vernier adjustment knob of platform, first set of devices (6) is moved to z axle positive dirction, the distance that moves is the length of a lattice correspondence of minimum scale on the spiral vernier adjustment knob; Reflection second set of devices (7) of signal processing circuit (23) output of utilizing pci data capture card (28) collection position detector (22) is utilized formula with respect to the voltage signal U2 of the position of first set of devices (6) $z=\frac{L}{2}\&times;\frac{U2-U1}{10}\&times;\frac{1}{\frac{2f}{l}-1},$ Determine the distance z of blade (8) with respect to initial position ₁, and z ₁As the lateral attitude coordinate of this position blade (8),

In the formula: f is the focal length of described first plano-convex lens (19) and second plano-convex lens (20), l is the vertical range at distance second plano-convex lens (20) convex front surface center on optical axis direction, back plane center of described first plano-convex lens (19), in this position, in the interferometric fringe signal of the reflection blade (8) of choosing output terminal (39) output that utilizes the diode photodetector (12) that pci data capture card (28) the collects Michelson interferometer that induced precession changes apart from the sinusoidal form of u in the equidirectional precession process of single P complete cycle signal and this p complete cycle correspondence the optical power change signal exported of the output terminal (40) that utilizes the silicon photocell detector (9) that pci data capture card (28) collects as data processing object (zone), and the normalization optical power signals amplitude of first data point in the data processing zone is designated as m1, the normalization optical power signals amplitude of last data point in the data processing zone is designated as n1, and the displacement u that utilizes the displacement conversion method of the blade (8) of complete cycle issue correspondence to calculate the reality of blade (8) in the equidirectional scanning process of this single is

λ is the reference light wavelength, and as query object, the cumulative function table of query criteria normal function is designated as m2 to the functional value of the cumulative function that finds for the horizontal ordinate of the point of (1-m1) the value of (1-m1); The value of (1-n1) as query object, the cumulative function table of query criteria normal function, the functional value of the cumulative function that finds is designated as n2 for the horizontal ordinate of the point of (1-n1), | n2-m2| is the variable quantity v of the integration variable horizontal ordinate of extrapolating in described blade (8) moving process from the cumulative function of normalized optical power change correspondence, utilize $\mathrm{\&omega;}\left(z\right)=\frac{2u}{v},$ Bring the value of u and v into, can try to achieve the size ω (z) of the light beam at this blade position place ₂

＜8〉repeating step＜7〉99 times, obtain a series of position z of blade (8) successively ₃To z ₁₀₀, and corresponding ω (z) ₃To ω (z) ₁₀₀

＜9〉compare ω (z) ₁To ω (z) ₁₀₀Value, minimum promptly is the size of beam waist, the position Z of the blade of this size correspondence (8) is position with a tight waist.

Images