• Korean Journal of Optics and Photonics
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• v.19 no.2
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• pp.144-149
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• 2008

Thermal distortion of the laser mirrors which are the Coude mirrors of the laser beam director and the wavefront error caused by the thermal distortion are studied. Coude mirrors consist of three relay mirrors and one fast steering mirror. The mirrors have reflectivity of 99.5% with respect to the laser wavelength of $3.8\;{\mu}m$, and absorption of 500 W per second. Thermal distortion and its related wavefront errors are studied with laser beam irradiation for 5 seconds. For the relay mirror, the wavefront error is 334 nm_PV, 98 nm rms and for fast steering mirror, $11.5\;{\mu}m$_PV, $3{\mu}m$ rms.

• Korean Journal of Optics and Photonics
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• v.15 no.3
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• pp.254-257
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• 2004

A null optical system for monitoring the alignment of the optical beam director is proposed instead of the conventional autocollimator alignment system. A null optical system for the optical beam director of aperture 30 cm is designed and its performance is analysed.

• Korean Journal of Optics and Photonics
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• v.16 no.6
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• pp.521-526
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• 2005

We assembled the optical beam director with diameter 300 mm. This consists of primary, secondary mirrors and 5 folding mirrors. Among them, the primary mirror is the most important component so that we measure any possible deformation on it at every step of assembly. Also, we developed the systematic alignment algorithm, which is essential because the number of mirrors is 7. The final wavefront error of the system is 1.9 wave rms (wave=633 nm) which is 7 times larger than we expected. The main source is the deformation of the 131ding mirrors. We expect that what we have learned from the assembly of this system would be helpful when we deal with a larger system in the future.