This interview reviews Westphal's family background, education, and early employment at the Seismograph Service Corporation and at Sinclair Research Labs, a division of Sinclair Oil Corporation, where he gained experience in designing and constructing a variety of instrumentation. The bulk of the interview is devoted to a thorough discussion of Westphal's career at the California Institute of Technology (CalTech), first as an instrumentation engineer and later as an associate professor and professor of planetary science. The interview documents his initial activities in the design and improvement of infrared detectors and telescopes, his pioneering work with the Silicon Vidicon photometers, and then his increasing interest and involvement in the science of infrared astronomy and planetary astronomy. Also covered in great detail is Westphal's work on the Wide Field Camera (WFC) for the Space Telescope (ST) project, including discussion of the evaluation of detectors, design, competing for the contract award, NASA's procedures and structure and their effect on the development of ST and its instrumentation, and the use of ST and WFC after launch. Other topics discussed include: NASA Infrared Telescope Facility; Smithsonian Astrophysical Observatory, Moonwatch project; Sputnik satellite projects; Charles Hewitt Dix; Heinz Lowenstam; Bruce Murray; Gerry Neugebauer; Frank (Francis) Low; and James Van Allen, among others.