Throughout my career, my research has focused on taking advantage of an historic opportunity. By the 1950's, it was understood that there were many interesting and important physical systems that could be investigated using photons with far infrared to millimeter wavelengths. However, the performance of measurement systems, including sources, spectrometers and detectors was so poor that most of the important experiments were not practical. My research has developed measurement tools for this spectral range and used these tools to work on the most interesting accessible physical problems, first in Condensed Mater Physics and then in Astrophysics and Cosmology.
Early scientific problems studied included energy gap measurements in superconductors, Josephson effect detectors, antiferromagnetic resonance, hemin compounds and hemoglobin, laser sources and molecules bound to metal surfaces. Studies of the far infrared and millimeter wave properties of solids at low temperatures provided the scientific background for the invention and development of vastly more sensitive detectors for these wavelengths. As we improved the detectors, it became possible to study astrophysical sources of millimeter waves. Our later work has focused on balloon-based measurements of the spectrum and anisotropy of the Cosmic Microwave Background Radiation. I was the principal investigator of the Woody-Richards experiment, which measured the spectrum of the CMB before COBE and the MAXIMA experiment, which measured the degree scale anisotropy of the CMB before WMAP.
My group, including students, postdocs and collaborators, has contributed to the development of important detectors and mixers for the millimeter and submillimeter bands. We invented and developed the SIS quasiparticle heterodyne mixer, which has improved the sensitivity of heterodyne receivers by a factor 102 and is widely used in millimeter wave radio astronomy. We invented the stressed Ge photoconductive detector, which is orbiting in the Spitzer Space Telescope. We designed and built generations of composite bolometric detectors with metal film absorbers, which have improved the sensitivity of direct detectors by a factor 108 and are the basis of many important cosmology experiments. Our team made the first balloon observations with 3He-cooled bolometers and with bolometers cooled to 100 mK by a miniature adiabatic demagnetization refrigerator.
I retired in 2004 and now hold an appointment as Professor of the Graduate School at Berkeley. I continue to work with the group that I started in 1966, which is now led by Professor Adrian Lee.