A prototype of a scalable and potentially low-cost stacked array piezoelectric deformable mirror (SA-PDM) with 35 active elements is presented in this paper. This prototype is characterized by a 2 μm maximum actuator stroke, a 1.4 μm mirror sag (measured for a 14 mm × 14 mm area of the unpowered SA-PDM), and a ±200 nm hysteresis error. The initial proof of concept experiments described here show that this mirror can be successfully used for shaping a high power laser beam in order to improve laser machining performance. Various beam shapes have been obtained with the SA-PDM and examples of laser machining with the shaped beams are presented.
High quality, efficient calibration of astronomical insiruments is a pre-requisite for the modern observatory. Each of the Gemini telescopes will be equipped with identical facility calibration units (GCALs) designed to provide wavelength and flat-field calibrations for the suite of instruments. The broad range of insirumentation planned for the telescopes heavily constrains the design of GCAL Short calibration exposures are required over wavelengths from O.3um to 5um, field sizes up to 7arcminutes and spectral resolution from R-5 to 50,000. The output from GCAL must mimic the f-16 beam of the telescope and provide a uniform illumination of the focal plane. The calibration units are mounted on the Gemini Instrument Support Structure (155), two meters from the focal plane, necessitating the use of large (400mm diameter) optical components.We will discuss the opto-mechanical design of the Gemini calibration unit, with reference to those features which allow these stringent requirements to be met. A novel reflector/diffuser unit replaces the integrating sphere more normally found in calibration systems. The efficiency of this system is an order of magnitude greater than for an integrating sphere. A system of two off-axis mirrors reproduces the telescope pupil and provides the 7' focal plane. The results of laboratory tests of the uniformity and throughput of the GCAL will be presented.
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