Solid state lasers

Details Solid state lasers Solid state lasers

1998-01-27

2000-03-21

Bovernick, Rodney

Abrading

Abrading process

Glass or stone abrading

B24B 100, B24B 719, B24B 730

Patent

active

060396326

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to solid state lasers and in particular, though not necessarily, to solid state lasers employing a slab-type lasing medium.
Many conventional solid state lasers employ a cylindrical lasing rod, for example of Nd:YAG, with mirrors placed at opposed ends of the rod. Lasing light propagates axially backwards and forwards along the rod causing amplified stimulated emission to occur. A problem with this arrangement is that the optical pump light applied to the rod generates heat which in turn gives rise to temperature gradients across the rod, i.e. transverse to the direction in which light propagates. The temperature gradients cause non-uniformities in the optical properties of the rod to arise, causing distortion and power loss in the light output of the laser. Whilst it is possible to alleviate the steady state problem by various means including use of liquid coolants, the problem of dynamic changes in temperature remains significant with respect to lasing performance.
More recently, rod-type lasing media have been replaced with elongate slabs having a rectangular or square cross-section, in an attempt to further reduce the problems caused by temperature gradients within the lasing media. In a slab-type medium, light propagates lengthwise along the medium in a zig-zag manner, reflecting alternately off the two opposed longer side faces of the slab which are polished smooth to maximise internal reflections. This is illustrated in FIG. 1.
The zig-zagging of the light path effectively averages out the effect of temperature gradients .DELTA.T.sub.b between the two opposed faces 1, 2 from which the light reflects, reducing distortion of the light beam and therefore improving collimation of the laser output beam. To remove heat from the slab it is usually cooled via one or both of the internally reflecting faces 1, 2, e.g. using a liquid coolant.
With slab-type lasing media however, there still remains the problem of temperature gradients .DELTA.T.sub.66 arising across the width of the media, i.e. between the side faces 3, 4 from which the light beam is not reflected.
It is an object of the present invention to overcome or at least mitigate disadvantages of known solid state lasers.
It is a further object of the present invention to reduce heat generation within solid state laser media and to reduce temperature gradients arising therein.
According to a first aspect of the present invention there is provided a method of reducing temperature gradients within an elongate solid state lasing medium, the medium comprising one or more substantially non-reflecting faces for emitting or scattering radiation generated by amplified spontaneous emission (ASE), the method comprising treating said non-reflecting face or faces to reduce the amount of heat generated by radiation passing therethrough.
Where the medium is provided with one or more preroughened faces, the or each face may first be polished visually smooth and then reroughened, such that the depth of surface damage at the roughened face is less than that of the original face. Thus, the scatter path at the roughened face is reduced and heat generation, due primarily to pump light, is also consequently reduced. "Roughening" may be taken to include producing a surface finish which scatters incident light. The finish may comprise periodic or random patterning.
Alternatively, faces of the lasing medium through which it is required to emit or scatter parasitic ASE light can be polished visually smooth and coated with a material whose thermal and optical properties are the same or similar to those of the lasing medium, but in which heat dissipation is less than that in the lasing medium. The outer surface of the coating is then roughened to provide a substantially non-reflecting scattering finish. Given the relatively low heat dissipation which occurs within the coating material, even a relatively large scatter path at the outer surface of the coating material will result in a relatively small amount of heat generation compared to that which wo

REFERENCES:
patent: 4899347 (1990-02-01), Kuchar et al.
patent: 4918703 (1990-04-01), Kukla
patent: 5084889 (1992-01-01), Tajima
patent: 5335237 (1994-08-01), Zapata

Affiliated with

Also associated with

Rating

Solid state lasers does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Solid state lasers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Solid state lasers will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-726017