Double arch mirror study. Part 1: Preliminary engineering report

In the proposed design, the NASA AMES 20-in double arch mirror is supported by three clamp and flexure assemblies. The mirror clamp consists of a T-shaped Invar-36 member that goes into a similarly shaped socket in the back of the mirror. The mirror socket is made oversize and contacts the clamp only along the conical surface. The clamp is preloaded by a spring washer and pulls the mirror into contact with the flexure. The clamp is then inserted into the mirror socket through a cutout, is rotated 90 deg, and is then pinned in place. Loading conditions considered in socket design are discussed as well as stress in the socket and clamp. Flexure geometry and stress are examined as well as the effects of flexure error and of mirror cell error

Double arch mirror study. Part 3: Fabrication and test report

A method of mounting a cryogenically cooled, lightweight, double arch, glass mirror was developed for infrared, astronomical telescopes such as the Space Infrared Telescope Facility (SIRTF). A 50 cm, fused silica mirror which was previously fabricated was modified for use with a new mount configuration. This mount concept was developed. The modification of the mirror, the fabrication of the mirror mount, and the room temperature testing of the mounted mirror are reported. A design for a SIRTF class primary mirror is suggested

Double arch mirror study

The development of a method of mounting light weight glass mirrors for astronomical telescopes compatible with the goals of the Shuttle Infrared Telescope Facility (SIRTF) was investigated. A 20 in. diameter double arch lightweight mirror previously fabricated was modified to use a new mount configuration. This mount concept was developed and fabricated. The mounting concept of the double mounting mirror is outlined. The modifications made to the mirror, fabrication of the mirror mount, and room temperature testing of the mirror and mount and the extension of the mirror and mount concept to a full size (40 in. diameter) primary mirror for SIRTF are discussed

Mueller Polarimetry for Quantifying the Stress Optic Coefficient in the Infrared

The stress optic coefficient of an infrared transmitting material was measured at room temperature at a wavelength of 1550nm. This work discusses a Mueller matrix imaging experiment to measure the stress optic coefficient, observe the spatial distribution of birefringence, and quantify experimental sources of uncertainty. A one-inch diameter disk of sample material was diametrically loaded with increasing force, and linear retardance was measured in the central region. Finite element and analytical modeling was done to estimate the magnitude of stress in this central region. A Rotating Retarder Mueller Matrix Imaging Polarimeter measured the spatial distribution of linear retardance. The retardance is related to the change in birefringence with stress magnitude. The slope of this linear fit is the stress optic coefficient. The stress optic coefficient of the infrared transmitting material was measured to be 1.89 ± 0.1424 [TPa]−1. To test the precision of our stress optic coefficient measurement procedure, a 1-inch diameter N-BK7 disk was measured at a wavelength of 1550nm and compared with industry-accepted values. The stress optic coefficient of N-BK7 was measured as 2.83 ± 0.1057[TPa]−1. The published N-BK7 value measured at visible wavelengths is 2.77 [TPa]−1 ± 3%.1-3 This agreement validates the experimental Mueller matrix imaging methods and supports the common assumption of minor wavelength dependence of the stress optic coefficient. © 2023 SPIE.Immediate accessThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Multibody Systems Modeling and Optimization Problems of Lower Limb Prostheses

To study the effect of prosthesis design on the kinematic, dynamic, energetic and other characteristics of an amputee\u27s locomotion and to improve and create new efficient lower limb prostheses it is expendient to use mathematical modeling of a human walk process and dynamic optimization techniques. In this paper a mathematical model is proposed for investigating the dynamics of a man\u27s skeletal system (MSS) with a below-knee prosthesis. A MSS is simulated by a plane controlled dynamic system of rigid masses. The controlled motions of the system are described by Lagrange\u27s equations of the second kind, and for the expressions for ki\uadneto-static balance of the prosthesis under the action of ankle and metatarsal moments and the forces of reactions are derived. An algorithm is construced for solving the pro\uadblem of human gait dynamics with a below-knee prosthesis. The series of dynamics pro\uadblems for multibody biothechnical system "Man-Prosthesis" and optimization of struc\uadtural parameters of the artificial lower extremity of a man has been solved