CN2927040Y - Interference measuring device of solid laser medium heat distortion - Google Patents

Abstract

The utility model discloses an interference measuring device for dynamic thermal distortion of solid-state laser medium, which comprises a He-Ne laser, a beam expander telescope, a first spectroscopy, a second spectroscopy, a first totally reflecting mirror, a second totally reflecting mirror, an observation screen, a CCD detector, and a computer; wherein, the He-Ne light produced by the He-Ne laser is divided into two beams by the first spectroscopy after passing through the beam expander telescope, a beam of the reflected light is reflected by the first totally reflecting mirror, then by the second spectroscopy after passing through the solid-state laser medium, the other reflected light passes through the second spectroscopy after being reflected by the second totally reflecting mirror, the two beams of light are interfered on the semi reflecting surface of the second spectroscopy, the interference pattern is imaged on the observation screen and are collected and then sent into the computer by the CCD detector to process data. The utility model is has the advantages of simple structure, easy manufacture, low cost and dynamic measurement of the temperature distribution of the slab laser medium without contact.

Description

The interferometric measuring means of solid laser medium dynamic heat distortion

Technical field

The utility model relates to laser medium, particularly a kind of interferometric measuring means of solid laser medium dynamic heat distortion.

Background technology

The distortion of working-laser material heat is to hinder the key factor that laser power further improves and obtain high light beam quality.Therefore effectively in real time the dynamic heat distortion of detection laser medium fully, is in depth understood the Temperature Distribution of working-laser material, and it is effectively compensated, to guarantee great-power solid laser continuously, efficient operation is very important.

In the heat distortion research of solid state laser, great majority all are Temperature Distribution, the thermal stress that the mode of employing numerical simulation is analyzed laser medium, [the thermal effect research of LD profile pump Nd:YAG laser instruments such as Zhang Ling such as thermal focal, laser and infrared, 2003, Vol.33, No.1], but can not obtain the Temperature Distribution of laser medium really and accurately.The heat distortion that utilizes interference technique exploring laser light medium that the also has [interference testing of YAG laser bar optical pumping dynamic thermal effect such as Luo Bikai, Chinese laser, 1993, Vol.A20, No.3], but only be used under the situation of monopulse pumping, and what obtain is three-dimensional skiodrome, does not obtain temperature profile.Also utilize in the pumping process, reference light is in the other end incident of laser crystal pumping, after the reflection of front/rear end, interfere mutually, [interferometric method such as Yang Yongming is measured LD end pumping Nd:YAG crystal thermal focal length to the thermal focal length of measuring crystal according to moving of taking place of the interference fringe that produces, the photon journal, in February, 2005, Vol.34, No.2], but adopt the degree of accuracy of this method not high.In a word, the Temperature Distribution of all failing in experiment, dynamically to measure laser medium of prior art, and do not have real-time, and handle more satisfactoryization, precision is not high.

Summary of the invention

The purpose of this utility model is to provide a kind of interferometric measuring means of solid laser medium dynamic heat distortion, and claimed structure is simple, debugs easily, can obtain the dynamic heat distortion of laser medium.

Technical solution of the present utility model:

A kind of interferometric measuring means of solid laser medium dynamic heat distortion, it is characterized in that laser instrument by He-Ne, beam expanding telescope, first spectroscope, second spectroscope, first total reflective mirror, second total reflective mirror, film viewing screen, ccd detector and computing machine are formed, the position relation of said modules is as follows: the He-Ne light that the He-Ne laser instrument sends is divided into two bundles through behind the beam expanding telescope by first spectroscope, a branch of transmitted light is reflected by first total reflective mirror through the laser medium of solid state laser, reflect through second spectroscope again, another folded light beam is through the second total reflective mirror reflecting ﹠ transmitting, second spectroscope, this two-beam interferes on second spectroscopical semi-reflective surface, interference pattern is imaged on the film viewing screen, and the interference fringe pattern is sent into computing machine by the ccd detector collection and carried out data processing.

Because the thermal effect that the measured laser medium produces during by pumping can change the refractive index of laser medium, and change of refractive will make the optical path difference by laser medium change, the interference fringe generation deformation that causes producing is with mobile, utilize ccd detector to take the interference fringe dynamic changing process continuously, obtain a series of interference fringe images according to time sequence.By analyzing these interference fringe pictures, calculate the change of refractive situation according to every bit on these bar graphs at the corresponding constantly progression that moves of difference, and calculate the heat distortion situation of laser medium according to change of refractive.For the more accurate fringe order that moves that obtains every bit correspondence on the striped, thereby adopted the way of Flame Image Process, through some steps such as image pre-service, adopt thinning algorithm to extract the skeleton that extracts striped at last, this brings great convenience for follow-up data processing.

Be example with side pump slab laser below, concrete computation process is as follows: set up the coordinate system (see figure 2), the length of establishing the slab laser medium is L, and the wavelength of surveying light (He-Ne light) is λ, and the refractive index of half bar medium of pumping is not n ₀, axial (z axle) refractive index gradient is zero after the pumping, cross section (x-y plane) gone up index distribution and is:

n＝n(x，y) (1)

Corresponding point (x, the variable quantity of optical path difference y) be Δ l (x, y), the striped number that moves past be Δ m (x, y), the change of refractive amount be Δ n (x y), has so:

Δl(x，y)＝Δm(x，y)·λ (2)

And have:

Δl(x，y)＝[n(x，y)-n ₀]·L＝Δn(x，y)·L (3)

Contrast (2) (3) two formulas have so:

$\mathrm{\Δn}(x,y)=\frac{\mathrm{\Δm}(x,y)\·\mathrm{\λ}}{L}---\left(4\right)$

The change of refractive amount that just can calculate according to the striped amount of movement like this.The temperature variation that temperature refraction rate coefficient dn/dt causes be the thermic refractive index change delta n (x, main cause y) are therefore approximately thought:

$\mathrm{\Δn}(x,y)=\mathrm{\Δn}{(x,y)}_T=\mathrm{\ΔT}(x,y)\·\left(\frac{\mathrm{dn}}{\mathrm{dt}}\right)---\left(5\right)$

Comprehensive above-mentioned two formulas (4), (5) then have:

$\mathrm{\ΔT}(x,y)=\mathrm{\Δn}(x,y)/\left(\frac{\mathrm{dn}}{\mathrm{dt}}\right)---\left(6\right)$

So just can obtain the slab laser medium by the Temperature Distribution in the pumping process, and also can directly obtain three-dimensional skiodrome from interference fringe.

Advantage of the present utility model or technological achievement are:

1, in the utility model, owing to adopt the method for interference fringe, the computer image processing technology of maturation is applied to handle striped, can access higher precision.

2, in the utility model,, can not influence the operate as normal of laser instrument because employing is the metering system of noncontact.

3, in the utility model,, can calculate the heat distortion situation etc. that change of refractive obtains laser medium because the interference fringe of ccd detector collection can import and handle in the computing machine and calculate.

4, in the utility model, because used device architecture is simple, whole device is stable to be used, and is convenient to processing and manufacturing.

Description of drawings

Fig. 1 is the structured flowchart of the interferometric measuring means of the utility model solid laser medium dynamic heat distortion.

Fig. 2 is the slab laser medium synoptic diagram of profile pump.

Concrete embodiment

Consult Fig. 1, Fig. 1 is the structured flowchart of the interferometric measuring means of the utility model Laser Measurement medium dynamic heat distortion.The interferometric measuring means of the utility model solid laser medium dynamic heat distortion as seen from the figure, by He-Ne laser instrument 1, beam expanding telescope 2, first spectroscope 3, second spectroscope 7, first total reflective mirror 6, second total reflective mirror 8, film viewing screen 11, ccd detector 10 and computing machine 12 are formed, the position relation of said modules is as follows: the He-Ne light that He-Ne laser instrument 1 sends is divided into two bundles through beam expanding telescope 2 backs by first spectroscope 3, a branch of transmitted light is reflected by first total reflective mirror 6 through the laser medium 5 of solid state laser, again through 7 reflections of second spectroscope, another folded light beam is through second total reflective mirror, 8 reflecting ﹠ transmittings, second spectroscope 7, this two-beam interferes on the semi-reflective surface of second spectroscope 7, and interference pattern is imaged on the film viewing screen 11, and the interference fringe pattern is gathered and sent into computing machine 12 and carry out data processing by ccd detector 10.

The laser that sends from He-Ne laser instrument 1 enters interferometer light path through beam expanding telescope 2, and the laser medium 5 in the light path collects the width of cloth interference fringe picture of this moment not by pumping by ccd detector 10 at this moment, preserves bar graph as a setting.

When pumping source 4 and 9 pairs of laser medium 5 beginning pumpings, gather storage by the interference fringe on the film viewing screen 11 of ccd detector 10 real-time continuous and send into computing machine 12, till pumping finishes.

Number for convenience of moving interference fringes on the accurate Calculation cross section, fringe center is handled and extracted to all interference fringes that collect, the a series of interference fringes and the background striped that collect during then with pumping compare, and analysis meter is calculated three-dimensional wave face, Temperature Distribution, equivalent thermal focal etc.

Having adopted a block size among embodiment of the utility model is the process of tabular laser glass simulated laser diode (LD) the pumping laser slab of 2cm*3cm*1cm, change two LD laser instruments 4,9 into two sides that two refrigerating sheets stick on laser glass, the experimental situation temperature is 20 ℃.Adopt the temperature of two refrigerating sheets of temperature control circuit control, its temperature difference is remained on about 60 ℃, the heat transfer process when simulating lath by pumping.

Put up light path earlier, clap a width of cloth background bar graph.Then laser glass is put into light path, ccd detector 10 was gathered 12 seconds altogether with the process of the moving interference fringes on the speed continuous acquisition film viewing screen 11 of per second 25 frames when refrigerating sheet is started working, and at this moment heat transfer process is basicly stable.

For the progression that more accurate calculating striped moves, must extract the center of striped earlier, according to the Theoretical Calculation of front, can obtain the dynamic heat distortion situation of this laser glass in heat transfer process.Show from experimental result: the result conforms to Theoretical Calculation, the utlity model has simple in structure, be easy to make, with low cost, can under non-contacting condition, the Temperature Distribution to the slab laser medium carry out kinetic measurement, and in pumping continuously, monopulse pumping or repetition pulse pumping, can both measure, be widely used.

Claims (1)

1, a kind of interferometric measuring means of solid laser medium dynamic heat distortion, it is characterized in that by He-Ne laser instrument (1), beam expanding telescope (2), first spectroscope (3), second spectroscope (7), first total reflective mirror (6), second total reflective mirror (8), film viewing screen (11), ccd detector (10) and computing machine (12) are formed, the position relation of said modules is as follows: the He-Ne light that He-Ne laser instrument (1) sends is divided into two bundles through beam expanding telescope (2) back by first spectroscope (3), a branch of transmitted light is reflected by first total reflective mirror (6) through the laser medium (5) of solid state laser, reflect through second spectroscope (7) again, another folded light beam is through second total reflective mirror (8) reflecting ﹠ transmitting second spectroscope (7), this two-beam interferes on the semi-reflective surface of second spectroscope (7), interference pattern is imaged on the film viewing screen (11), and the interference fringe pattern is sent into computing machine (12) by ccd detector (10) collection and carried out data processing.

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