Biomedical subjects
Publications and source records attributed to Geoff Andersen.
A photon sieve with 10(7) holes has been constructed for operation at optical wavelengths. Details of the design, fabrication, and performance of this device are presented. The 1 m focal-length, 0.1 m diameter element is diffraction limited over a significant bandwidth and has a moderate field of view.
I have constructed a 1-m-diameter telescope using separate, low-quality spherical primary mirror segments. A single hologram of the mirrors is used to correct the random surface distortions as well as spherical aberration, while simultaneously phasing the individual apertures together. I present experimental results of the removal of an error of thousands of waves to produce a diffraction-limited instrument operating over a narrow bandwidth. This technique promises to have many benefits in future space-based telescopes for imaging, lidar, and optical communications.
We have designed a novel rotational Raman and Rayleigh lidar system that incorporates a simple holographic optical element. The hologram simultaneously disperses and focuses the backscattered signal light so that narrow spectral features can be isolated and detected with high efficiency. By measuring the relative strength of several nitrogen rotational Raman lines, we can obtain an accurate temperature of the atmosphere at a given altitude without the need for external calibration. Simultaneous photon counting of the Rayleigh backscatter signal permits temperature measurements at much higher altitudes.