Holographic Technology for Solar Energy Concentration. Final Report and 1983 Annual Report

摘要

The objective of 3-year R and D project has been to explore the possibility of using dichromated-gelatin holographic technology for solar energy concentration. Special emphasis has been given to spectrum-splitting holoconcentrators based on the stack of sub-holograms focusing adjusted parts of solar spectrum to various photocells with different band-gaps. Reflection Bragg holograms have been preferred because of low chromatic dispersion and flatter shape of spectral characteristics. During the last year, significant progress has been made in the photochemistry, physics and optics of the holoconcentrators. It was verified that in Lippmann geometry, the reflectivity of the selective holographic mirrors can reach at least 99.9%, i.e., the photochemistry of the dichromated gelatin to a good approximation preserves the physical properties of reflection Bragg holograms. In holoconcentrator geometry, the hologram diffraction efficiency, limited only by Fresnel losses, has been obtained (up to 92%) and it was shown that in the case of zero-dispersion gratings with curved holographic coatings, the optical efficiency of the holoconcentrator system can reach this value. Hence, the holoconcentrator systems can be uniquely very close to the ideal PV spectrum-splitting systems. Moreover, several additional attractive holographic applications, such as high-efficiency selective reflective filters, holographic mirrors for long-path multi-gas optical sensors, heat holowindows and laser-protection selective mirrors, have been developed. (ERA citation 10:038959)