Proceedings Article | 17 September 2013
KEYWORDS: Mirrors, Mercury, Beam expanders, High power lasers, Image quality, Quality systems, Laser damage threshold, Interferometers, Finite element methods, Spherical lenses
As currently, laser calibration, laser radar, laser ranging and the relative field raised up the demand for high
magnification laser beam expander. This article intends to introduce a high-energy laser beam expander research and
design, large- diameter, wide-band, high-magnification and small obscuration ratio are the main features. By using
Cassegrain reflective optical system, this laser beam expander achieves 24 times beam expand, and outgoing effective
limiting aperture is Φ600 mm, band scope between 0.45μm to 5μm, single-pulse laser damage threshold greater than
1J/cm2, continuous-wave laser damage threshold greater than 200W/cm2 and obscuration ratio 1:10. Primary mirror
underside support uses 9 points float supporting, lateral support mainly depends on mercury belt support and assists by
mandrel ball head positioning support. An analyzing base on finite element analysis software ANSYS, and primary
mirror deformation status analysis with debug mode and operativemode, when inputs four groups of Angle 170°, 180°,
210° and 240° , mercury belt under each group of angle load-bearing is 65%, 75% , 85% and 100% respectively, totally
16 workingcondition analyze results. At last, the best way to support primary mirror is finalized. Through design of
secondary mirror to achieve a five-dimensional precision fine-tune. By assembling and debugging laser beam expander,
Zygo interferometer detection system proof image quality (RMS) is 0.043λ (λ=632.8nm), stability (RMS) is 0.007λ
(λ=632.8nm), and effective transmission hit 94%, meets the requirements of practical application completely.
