Use of thermal sieve to allow optical testing of cryogenic optical systems.
Full aperture testing of large cryogenic optical systems has been impractical due to the difficulty of operating a large collimator at cryogenic temperatures. The Thermal Sieve solves this problem by acting as a thermal barrier between an ambient temperature collimator and the cryogenic system under test. The Thermal Sieve uses a set of thermally controlled baffles with array of holes that are lined up to pass the light from the collimator without degrading the wavefront, while attenuating the thermal background by nearly 4 orders of magnitude. This paper provides the theory behind the Thermal Sieve system, evaluates the optimization for its optical and thermal performance, and presents the design and analysis for a specific system.
Cryogenic Thermal Mask for Space-Cold Optical Testing for Space Optical Systems
An optical testing configuration utilizing the Cryogenic Thermal Mask (CTM) provides thermal decoupling between a cryogenic optical system under test and a collimator operating at ambient temperature, while passing the test wavefront without significant degradation.
Optical emission spectroscopy of self-sustained magnetron sputtering
Abstract The results of plasma investigation during very high power magnetron sputtering processes are presented. Magnetron sputtering during both standard and self-sustained modes was investigated. Owing to very effective target cooling and appropriate magnetic field distribution, the high target power density could be reached (up to ∼1000 W/cm 2 , ∼1.5 A/cm 2 ). A copper target 50 mm in diameter and 7 mm in thickness was used during the experiments. Two modes of magnetron sputtering, i.e. standard and self-sustained, were investigated. Optical emission spectra were measured. The emission intensity of the Cu species as a function of target power density during both magnetron sputtering modes was observed. The spectra were observed in the 200–800 nm wavelength range. When target current rose, the emission intensity of copper ion lines increased and neutrals ones decreased.