CN103840360B

CN103840360B - Thin lens laser

Info

Publication number: CN103840360B
Application number: CN201410113935.0A
Authority: CN
Inventors: 李育德; 刘静伦; 陈梅
Original assignee: Sichuan University
Current assignee: Sichuan University
Priority date: 2014-03-26
Filing date: 2014-03-26
Publication date: 2017-02-08
Anticipated expiration: 2034-03-26
Also published as: CN103840360A

Abstract

The invention relates to the technical field of optics, optical engineering, laser devices and laser, in particular to an establishing method and device of a solid laser. Solid state laser media with good performance, a resonant cavity, a semiconductor laser array or other even light sources are mainly used for obtaining high power or high energy output in a pumping mode. The thin lens laser is characterized in that a solid laser medium block is machined to be a thin lens which can carry out radiating easily, the front surface of the thin lens is a coating film total reflection spherical surface, the spherical surface of the back surface, except the center position, of the thin lens is a total reflection face, the center position is a coating film semi-reflection face, and laser light is output through the semi-reflection face.

Description

Thin lenss laser instrument

Technical field

The present invention relates to optical engineering, laser engineering, laser technology field.

Background technology

Solid state laser, mainly has Nd:YAG laser, neodymium glass laser etc..Solid state laser typically adopts bar-shaped Jie Matter, two ends polish, polishing, plate anti-reflection film in end face, using external cavity type work.In order to increase output, general employing is connected Formula or parallel, encourages multiple dielectric rods simultaneously, is also adopted by external cavity type work.Because dielectric rod has thermal lensing effect, from And so that laser beam quality is affected, people to avoid heat effect using thin plate medium strip or multiple laminated dielectric, and improves note Enter power or energy.Higher high light beam quality can be obtained using thin plate medium strip or multiple laminated dielectric and exocoel work to swash Light output.Why using exocoel work, no inner chamber solid swashs laser instrument to solid state laser, and corresponding technical problem is：Because Dielectric rod be heated uneven be easily deformed, in addition thermal lensing effect then be more difficult to consider inner-cavity structure, another aspect dielectric rod is relatively Long that entirety is inconvenient as optical element processing；Thin plate medium strip adopts Z-shaped light path exocoel work double to thermal distoftion and thermic Refraction effect has compensation elimination effect, but the no Z-shaped light path inner chamber of conjunction or no consideration inner chamber；Many flake structures can only be using outer Chamber works.

Content of the invention

The present invention is exactly directed to the fact that no inner chamber solid swashs laser instrument and relevant art problem and proposes.The present invention Solid laser medium thin lenss laser instrument, provides a kind of inner chamber solid state laser, and laser instrument has structure simply, output Or the feature that energy is larger.Relevant art problem is to solve by following scheme.

It using the solid laser medium of characteristic good as the material of thin lenss, using the thickness of thin lenss as laser medium Length, using the width of thin lenss as the length of gain medium；

Become two minute surfaces of resonator cavity with two surfaces of thin lenss after plated film, with the central authorities of wherein one side as portion Reflecting surface is divided to make output coupling；

With semiconductor laser or other Uniform Irradiation light sources for pump light, uniform spoke be can achieve by semiconductor laser array pumping According to pumping, and laser medium is higher to the absorbance of pump light, and used heat is less, is conducive to overcoming the heat of solid laser medium abnormal Change, thermal lensing effect；

Overcome thermal distoftion, the thermal lenss of solid laser medium because thin with the well radiating that thin slice or lamellar bring Effect, can be reduced to fairly small degree, or only at edge with the presence of to a certain degree thermal distoftion；

The Z-shaped light path of intracavity of lens laser device and the Z-shaped light path of sheet laser device exocoel are very close to therefore to thermal distoftion and heat Birefringence effect is caused to have compensation elimination effect；

The even variation of the radius of curvature that the even variation of lens causes no negatively affects to laser output in principle；Conventional Solid-state laser medium Nd:The thermal coefficient of expansion of YG is 8x10^-6.^oC^-1,0-250^oC, when lens laser device thickness is far smaller than table The radius of curvature in face, uniform for temperature situation suitable control can make the change of lens curvature that laser cavity work will not be made to be subject to bright Development rings；

Even if lens have the special change in local outside central area, remaining symmetric part of lens still can do as usual as laser Device works；

Suitable thickness and supporting way can keep that the deformation of lens is slight, and the generation to laser has no significant effect.

Brief description Fig. 1 is the vertical section schematic diagram of thin lenss laser instrument, and thin lenss are circular or oval Shape or square, 1 represents front surface or the upper surface of lens laser device, and radius of curvature is ρ₁, 2 represent that thickness is the saturating of d Mirror laser medium, 3 is light path, and 4 represent rear surface or the lower surface of lens laser devices, and radius of curvature is ρ₂, 5 is lens laser The output coupling face of device, a diameter of D₀, positioned at the central authorities on rear surface, 6 is metal heat sink or heat exchanger, and 8 is pump light source, Fig. 2 is the front surface of Fig. 1 lens laser device or the schematic diagram of upper surface, and 7 is symmetrical bar shaped sanding face, a width of b, Broken circle represents the position corresponding with Fig. 15.In conjunction with accompanying drawing, its operation principle is described further.It is sharp in figure 1 The total reflection coated surface of light, is the transmission plane of pump light simultaneously again, lens medium thickness generally 6mm about, 4 are all-trans for laser Penetrate face, pump energy transmissive goes out this face, and 6 inner surface is also sphere, and radius of curvature is approximately consistent with 4, to pump light total reflection So that laser medium is made with secondary pumping, on the right side of Fig. 1, oscillation light transmits between upper and lower two spheres along 3 directions of arrow, transmit in Between the fractional transmission through output coupling face 5 for the position and export, the part reflection of coupling surface makes light wave continue to come and go between two surfaces Transmission, the then light wave return when being transferred to symmetrical with the right side position in left side, the fractional transmission again when returning to middle position And export, part reflection makes the continuous round-trip transmission of light wave return to the right side then, then again left and right running, until light accurately return to former go out Send out point and orientation just starts new round round-trip transmission.If the total degree that the many journeys of wheel come and go is N, ripple transmits n times between two surfaces After be changed into its own.By design can make a wheel only comprise from right to left more from left to right such a single many journeys come and go, can Accurately it is returned to former starting point and direction.Positioned at radius r₀Light that locate, that direction is taken from the front surface center of curvature is past through n time Radius 0.5D is reached after returning₀Position and part outgoing.If the coordinate of original light is（x₀,y₀）, initial slope is（x’₀,y ’₀）, x under conditions₀=0 and x '₀=0 has y₀=r₀, y’₀=r’₀, and the n effect through round_trip matrixes can get 0.5D₀Position The slope of light, thus can obtain outgoing ray relative in the slope of optical axis.

Embodiment：Continuous wave or quasi c. w. lens laser device adopt Nd:This mechanical performance of YAG, optical property, Heat dispersion and the new laser medium of the excellent material of hardness property and similar nature, low-repetition-frequency or pulse lens swash Light device can adopt nd glass laser medium.This two classes laser medium can carry out optical manufacturing.Because lens laser device medium with general Close, their more machinable optical crystal media hardness height of penetrating mirror, therefore the optical manufacturing of lens laser device is Easy to perform and should carry out by optical lenses processing request.Optical maser wavelength is selected to be 1.06 μm, for 1.06 μm of light The coating raw material of reflection and transmission is hard material, and in recent years the lot of research of the fast light impact strength of this film is made The enough intensity that has use as hysteroscope face.Wavelength for pump light is typically selected in 0.81 μm, and 0.75 μm, be solid state laser Actually used.Pump light adopts array semi-conductor laser, be also existing solid state laser practical and have far-reaching significance side Case, also can utilitarian design krypton lamp etc..Radiator adopts aluminum metal radiator, and in addition to the punching of middle position, remainder can be adopted With some fin being attached thereto.The upper or front surface of duralumin first can become a radius of curvature bent with convex lens surface with lathe milling A close concave surface of rate radius, then with the method for optical manufacturing, it is processed so as to radius of curvature and lens radius of curvature base This is equal, and this has been the problem completely solving in reality, and the upper surface of lens laser device or front surface can enter sector-style Cold etc..Radiator also can also can carry out air-cooled, but preferably adopts more constant cooler environment or condition so that lens laser device Temperature more all permanent, and scalable cooling condition, make the thermal change of lens tend to uniform.

Implementation example：Nd by a diameter of 30mm:YAG rod is cut to long 100mm, a width of 30mm, and thickness is the thin plate of 6.3mm, By optical element requirement, its front surface or upper surface are processed as concave surface, surface curvature radius is 9600mm, rear surface bent or Person's lower surface is processed as convex surface, and surface curvature radius is the lens of 9560m, and concave surface plates the total reflection film of 1.06 mum wavelengths, Convex surface central radius are the semi-reflective film of region plating 1.06 mum wavelengths of 2mm, and transmitance is 10%.Bar shaped sanding face width b= 0.3mm.Select multiple matrix array semiconductor lasers that its concave surface is illuminated.Radiator one long 12cm, wide 6cm, thickness The hard alloy aluminium block of 15mm to be processed as material, a diameter of 4mm of interstitial hole, first its back side milling rectangularity radiates Chip arrays, fin thickness 0.5mm, wide 10mm, spacing 1mm, then its front is processed as radius of curvature is approximately the recessed of 9560mm Face and approximately polishing.The hundreds of watts of angles of divergence can be obtained when pump light is sufficiently strong and cooling is good enough and be approximately the defeated of 20mrad Go out, if there being the Nd of larger diameter：YAG is more preferably.Neodymium glass material can use as the medium of pulse lens laser device, in a word The medium of continuous wave solid state laser, can it is possible to medium as continuous wave output or the lens laser device of pulse output Medium for pulsed solid stale laser can serve as the medium of pulse lens laser device, and adaptable key point is that it is Thin it is easy to radiating and reduce temperature difference.

A kind of solid state N d:YAG thin lenss laser aid, by plated film total reflection concave surface 1, lens on front side of laser medium 2, lens Bar shaped on rear side convex spherical plated film fully reflecting surface 4, convex spherical central authorities plated film semi-reflective surface 5 on rear side of lens, lens front side surface Sanding face 7, radiator 6 and pump radiant 8 form, and concavo-convex coated surface is lens front-back, in convex surface central authorities and heat exchanger 6 Central aperture is alignd, and pumping radiant 8 is located at concave lens surface side it is characterised in that laser medium area is lens medium area, lens Coated surface is the resonator mirror of laser instrument in front and back, and output coupling is located at rear face center.

Claims

1. with solid-state laser material as laser medium, plated film minute surface is hysteroscope to one kind, meets steady-state conditionss, pump optical pumping, heat is handed over Parallel operation radiates, the solid state laser that the pump light overcoming thermal lensing effect and thermal distoftion with Z-shaped light path enters from medium concave surface end face Construction method it is characterised in that laser material block is processed to a large-sized circle thin concavo convex, or large scale is ellipse Circular thin concavo convex, or large scale square concave-convex thin lenss, the concave surface of lens is the total reflection concave surface of plated film, but with bar shaped mill Concave surface is divided into some symmetric fanning slab region by hair side, and the convex spherical central authorities of lens are plated film semi-reflective surface, and remaining region is Plated film fully reflecting surface, passes to sector from the light wave of fan-shaped slab region the initial segment minute surface between concavo-convex minute surface through multiple reflections Area face latter end minute surface tailing edge backtracking, to the initial segment minute surface, forms cavity oscillations in Z-shaped light path, each Z-shaped light path inner chamber oscillation light Ripple, from the part reflecting face output in minute surface central authorities, forms symmetry output beam.

2. a kind of solid state N d:YAG thin lenss laser instrument, by Nd:YAG laser medium（2）, on front side of laser medium lens, plated film is all-trans Penetrate concave surface（1）, convex spherical plated film fully reflecting surface on rear side of laser medium lens（4）, the half reflection plating in convex spherical central authorities on rear side of lens Face（5）, bar shaped sanding face on lens front side surface（7）, heat exchanger（6）With pump radiant（8）Composition, concavo-convex coated surface For lens front-back, convex surface central authorities and heat exchanger（6）The alignment of central centerline hole, pump light source is located at concave lens surface one Side is it is characterised in that laser medium area is bar shaped sanding face（7）The lens medium area separating and connecting as one, bar shaped sanding Some symmetric fanning slab region concave surface that face is divided into forms inner chamber reflecting surface, the output coupling of each Z-shaped light path inner chamber with convex surface Positioned at rear face center.

3. thin lenss laser instrument according to claim 2, its laser medium is that the Solid State Laser that can be processed into thin lenss is situated between Matter.