With the f/2.4 focusing optics on one of the eight Helios CO2 laser beam lines, direct backscattered light from a variety of glass microballoon targets has been observed. The quantities. that have been measured include: (1) the total backscattered energy; (2) relative amplitudes of the backscattered fundamental and low harmonics (n=1, 2, 3) of the 10.6 μm incident light; (3) the 3/2 harmonic emission from a double pulse backscatter experiment; (4) the temporally resolved 10.6 pm light using a fast pyroelectric detector and a Los Alamos 5-GHz oscilloscope; and (5) the time-integrated spectrally resolved fundamental using a 3/40meter spectrometer and a high resolution pyroelectric detector array (resolution ≈ 40 Å at 10.6 μm). The suitability of these diagnostics for evaluating the CO2 laser plasma in terms of stimulated scattering processes, plasma density gradients, velocity of the critical surface, etc., is discussed.
D. E. Casperson,
"Optical Diagnostics Of CO2 Laser Fusion Targets Using Backscattered Light", Proc. SPIE 0288, Los Alamos Conf on Optics '81, (30 December 1981); doi: 10.1117/12.932087; https://doi.org/10.1117/12.932087