Laird A. Thompson Professor Emeritus

My new book from Cambridge University Press (2020/2021) is now available at Amazon.com:

Galaxies & Cosmology (1974-1987): Early in my career I studied clusters of galaxies, galaxy morphology, and did galaxy redshift surveys. While working primarily with collaborator Stephen A. Gregory (U. New Mexico, Prof. Emeritus), I completed a series of deep wide-angle redshift surveys to study the galaxy distribution in and around the richest galaxy clusters in the nearby universe. When mapping the 3D galaxy distribution with a complete magnitude-limited redshift survey in the direction of the Coma cluster and the cluster A1367, Gregory and I recognized for the first time large voids in the galaxy distribution ( (Gregory and Thompson 1978. ApJ vol. 222, p. 784). In this 1978 paper we used the term "voids" for the first time in the astronomical literature. By doing so, we implicitly posed a challenge to theoretical cosmologists to explain this completely unanticipated structure in the galaxy distribution. In 2020 Cambridge University Press published my book entitled The Discovery of Cosmic Voids. It presents a detailed description of our discovery and its relationship to the other observational and theoretical work of our contemporaries. I show how each successive redshift survey -- CfA, Las Campanas, 2dF, SDSS -- confirmed the significance of the beautiful & intricate filamentary structure traced by the large scale distribution of galaxies. My book is available for purchase at Amazon.com .

Instrumentation (1982-1990): In the early 1980's I began to work on projects aimed at improving in real-time the image quality at ground-based telescopes. The was before any astronomical adaptive optics systems existed. My first instrument was a microprocessor controlled tip-tilt system called ISIS which was built while I was working at the Institute for Astronomy and was used at Mauna Kea Observatory (Thompson and Ryerson 1983, Proc. SPIE, vol.445, p. 560). Following Foy & Labeyrie's suggestion that laser guide stars might provide an excellent reference source for Adaptive Optics (AO) systems, I initiated the first effort to project a sodium laser guide star into the mesosphere above Mauna Kea Observatory (Thompson and Gardner 1987, Nature, vol. 328, pg. 229). This was followed by 3 years of intense work with Chester Gardner and his students in the Univ. of Illinois Electrical and Computer Engineering Dept. to define many of the pioneering aspects of laser guided AO systems, results that we published in the Proc. IEEE. Unknown to us at that time, a parallel laser guided AO development effort was underway by the U.S. Air Force. How our work helped to trigger the declassification of this Top Secret research is described in the section AO History. In the last 25 years laser guided adaptive optics technology has been integrated into every large state-of-the-art ground-based telescope, and it is one of the foundation-technologies of the next generation of giant telescopes. Those of us who pioneered this technology know what a struggle it was to convince conventional astronomers to incorporate AO technology into even a single large telescope. My initial requests for NSF funding were rejected (in 1987 and 1988), but my third funding request (submitted in 1989) was funded only after the US Air Force let it be known that they had already succeeded in building and operating their own laser guided adaptive optics system behind the cover of military secrecy.

Adaptive Optics Work (1990 - 2011): In 1990 I obtained funds from the National Science Foundation to begin experiments with Rayleigh scattered UV laser guide stars. These experiments with a 35 Watt Excimer laser led directly into my Mt. Wilson laser guided AO system called UnISIS. Unlike AO systems on giant telescopes, UnISIS has an open and flexible design. It is laid out on a large optical bench at the Coude focus of the Mt. Wilson 2.5-m telescope. UnISIS has both laser guide star and natural guide star AO capabilities. Two science cameras allow images to be taken simultaneously at visual and at near-IR wavelengths. On the right is an image of a star taken with UnISIS at 2.12 microns (Ks-band) with a Strehl ratio of 0.67. Following the publication of the 2009 summary paper describing UnISIS (Thompson et al. 2009, Pub. ASP, 121, 498-511), I began to work on other projects. Although the system is still operable (I last ran it experimentally in 2014), it is essentially furloughed.

Nebular Spectrograph Work (2011 - present): Any astronomical source with a large angular extent and a uniform surface brightness can be detected spectroscopically equally well with a large or a small aperture telescope. The large aperture telescope will provide results with a higher spatial resolution than the small aperture telescope, but both will produce spectra at the same "speed". Although this fact was recognized as early as 1910 by Vesto Slipher, and was eloquently described by Edwin Hubble in his book "Realm of the Nebulae" (it was Hubble's tribute to Slipher), nebular spectrographs on smaller telescopes are generally not exploited these days. I have recently built a fiber-fed nebular spectrograph and have begun to use it at Mt. Laguna Observatory, the only major observatory in California that is not compromised by light pollution. I have placed 14 optical fibers (in a so-called "Integral Field Unit") at the focal plane of a 0.25-m telescope to feed light into the spectrograph. The first results of this research are briefly described here: Nebular Spectrograph. My development work was slowed when I took a significant amount of time away from this project to write my book on "The Discovery of Cosmic Voids".

Postdocs Past & Present	Grad Students Past & Present	Other Links
Paul Eskridge 1987-1989	Christopher Neyman 2002	Contact Information
Peter McCullough 1993-1995	Michelle Griffin 2003	Teaching
Robert Gruendl 2002-2004	Samuel Crawford	Academic Biographical Information
Abhijit Chakraborty 2004-2006		Personal Highlights