Spaced-based mirrors that operate in cryogenic temperatures have a decreased gravity sag value than their phase maps at 293k. To characterize how the gravity sags changes at cryogenic temperatures a 1.2m aluminum mirror made of 5083 had a horizontal rotation test done for N=3 rotations (0°, 120°, 240°) for multiple temperatures ranging from 293k to 35K.

Large Aperture Mirrors (LAMs) are critical components of space- and ground-based telescopes and surveillance systems. The need exists in assessing temporal multiple modality dynamics of various types of LAMs, including recently developed mirrors with membrane support structure and 3D printed mirrors. This presentation discusses practical results for Whole-Field Laser Doppler Vibrometer (WF-LDV) - a newly developed instrument capable of instantaneous characterization of LAM’s vibrational spectra. Contrary to typical single beam scanning LDV or laser-beam array matrix LDV, the whole-field LDV used in this study operates in global mirror illumination mode while pixilation of the data is performed at the receive. Given the capacity of the WF-LDV to capture and characterize structural vibration in real time with negligible latency, it is possible to adaptively excite and probe the LAM allowing rapid convergence on resonant modes combined with Dynamic Mode Decomposition of the dynamics of the mode evolution.

Optics manufactured in a gravitational field are made with inherent internal stresses. When these optics are removed from the gravitational field (I.E., put into space) these stresses release. This is referred to as G-release. Theory offers methods of predicting the resulting 0-G shape of these optics. The intent of this paper is to compare results of real data measured on the same mirror from two separate methods; the ‘N-1 rotation test’ and the ‘face up/face down test’.

Photonic lanterns are a powerful emerging technology with critical applications in wavefront sensing, ultra-resolution hyperspectral imaging, telecommunications, adaptive optics for deep turbulence, LIDAR, directed energy, and astronomical investigations of extrasolar planets. A photonic lantern is a monolithic optical fiber device consisting of a smooth, continuous 3-D waveguide transition that implements spatial transformations. The lantern effectively decomposes the input light into eigenmodes of the lantern, with each mode corresponding to an output SMF. Thus, we can measure the distribution of intensities among the output single-mode beams to reconstruct the incoming optical field. Our group has pushed lanterns to high coupling efficiencies, with demonstrated broadband (400-700nm) transmission >91%, with efficiency rising to >97% for wavelengths approaching 1000nm and beyond. A rapidly expanding application of photonic lanterns is in the area of wavefront sensing. We will present our recent developments for Photonic Lantern WaveFront Sensors (PLWFS), with particular emphasis on their potential applications for optical system metrology and aberration control.

This study explores a novel approach for optical system surface finish using Gas Cluster Ion Beam (GCIB).

We discuss optical elements based on the sulfur monochloride copolymers (DSG: disulfide glass, poly(S2-TIC-Cl2)) for IR imaging applications. DSG copolymers show high refractive index, excellent transparency, low birefringence, and low dispersion compared with conventional optical polymer materials. The excellent thermomechanical properties allow for both molding and diamond-turning fabrication. The diffraction angle of a molded optical diffraction grating agreed well with the design and a diamond-turned plano-convex lens shows a 1.8 times larger imaging area compared to a BK-7 lens of the same dimensions.

Structural design of optical components launched into space requires fracture mechanics properties. To perform component design of a calcium fluoride (CaF2) prism, the fracture toughness and slow crack growth parameters were measured on the {100}, {110} and {111} low index planes. The fracture toughness is lowest on the {111} plane at 0.35 ± 0.01 MPam with a very flat cleavage surface exhibited during both fracture toughness and strength testing. Slow crack growth was significant on the {111} plane with a power law exponent of n = 30 ± 8. For engineering purposes, slow crack growth was insignificant on the {100} and {110} planes with n > 75. The facture surfaces have distinct patterns that are indicative of the cleavage plane. Biaxial testing with disks implies that design for general multiaxial states should be based on {111} strength and crack growth properties.