Sharpening Images using Guidestars at the Hale Telescope

The SIGHT Senior Project team at Cal Poly San Luis Obispo designed and prototyped the Science Cryostat subsystem of the Sharpening Images using Guidestars for the Hale Telescope (SIGHT) Adaptive Optics system. SIGHT will improve the capabilities of astronomical observations and measurements at the Hale Telescopes using adaptive optics. SIGHT will consist of a Laser Guidestar (LGS) subsystem which focuses a UV laser into Earth’s high atmosphere, adjacent to a science target the Hale Telescope is observing. The LGS subsystem calculates how the laser light has been distorted by temperature and pressure differences as the light travels through the atmosphere. The Science Cryostat subsystem will be located within Hale Telescope’s baffle tube, which will collect the science target light from the telescope’s secondary mirror and provide AO wavefront correction to sharpen the image using information from the LGS subsystem. The light is relayed through mirrors in the Science Cryostat to instrumentation below for imaging or taking measurements. The final design of the Science Cryostat contains optics, optic mounts, a baseplate, bipods, radiation shielding, a pressure vessel, a cooling system, and vacuum interfaces. A verification prototype was manufactured and delivered for future testing and project development. This report presents the project’s scope of work, concept design decisions, preliminary design analysis, critical design analysis, and final design changes. The final design presented in this report reflects the culmination of numerous design iterations improved based on research, feedback, analysis, and project developments to fulfill the problem definition as determined by the project sponsors at the California Institute of Technology (Caltech). Further recommendations for design improvements and testing procedures are presented in this report. The Science Cryostat is scheduled for implementation into the Hale Telescope in 2023