Page 326 - High Power Laser Handbook

294 So l i d - S t at e La s e r s Heat-Capacity Lasers 295

Beam quality
10
9
8
7
Early fall 2005
6
Late fall 2005
5
4
3
Spring 2006
2
1
0 1 2 3 4 5
Seconds
BK7 window, no diffusers Fused silica window
FS window, with diffusers (Model)
(Model)

Figure 11.31 Improvements in beam quality (times the diffraction limit) as a result
of changes made to the laser.

11.5 Scaling Approaches
The HCL’s architecture described in this chapter has confirmed that
significant amounts of laser output power (67 kW of average output
power) can be produced in a very small volumetric footprint via an
extremely simple, straightforward laser cavity design. The five laser
gain module HCL shown in Fig. 11.28 could fit on a typical dining
room table. The power of the HCL scales linearly in each of the fol-
lowing three independent methods:

• Adding more inline laser gain media (slabs)
• Increasing the cross-sectional area of the laser gain media
(and a corresponding increase in diode pump light)
• Increasing the duty cycle of the high-powered diode arrays

The simplicity of increasing any or all of these three parameters
makes for a very straightforward, practical approach to increasing
the HCL’s output power.
Looking ahead to the next level of power, a concept design for a
megawatt-class HCL is as follows:

• 16 transparent ceramic Nd:YAG laser gain media arranged
in series
• Each gain medium equipped with a 20 × 20 × 4 cm–thick slab