Abstract

Double-exposure Fourier transform holographic interferometry using a pulsed, long coherence length Nd:YAG laser is reported. The recording medium is pure and iron doped lithium niobate. Interferometry experiments with λ₁ = 532 nm only and λ₁ = 532 nm with λ₂ = 1064 nm simultaneously present (two-photon recording) have been conducted. Pulsed recording of holograms in undoped crystals is possible with acceptable results but low diffraction efficiency. The diffraction efficiency and the sensitivity are greatly enhanced by simultaneous presence of the 1064-nm line as expected with the holograms permanently stored in the crystals. These recording techniques are applied to recording and visualization of transient aerodynamic flow field phenomena. Good results are also obtained in heat transfer studies from electronic chips.

© 1989 Optical Society of America