The recent progress in chemical lasers is reviewed from a technical standpoint, including the authors' works. The performance characteristics of the individual chemical lasers is briefly compared in terms of pumping reaction, laser wavelength, output, and efficiency, where their applications such as spectroscopy and laser fusion are described. Especially on HF lasers, the initiation technique, preparation of an H2/F2 mixture, fluorine handling, and waste disposal are discussed. The spectroscopic application of a chemical laser to CO2 molecule is mentioned and some methods of 16μm laser emission by an HBr laser pumping are presented. Finally, the maximum storable energy of a photochemical iodinelaser is discussed.
With a view to separating isotopic bromine by the use of the laser, the absorption spectrum of bromine molecules, 1∑, (0+g) (ground level)→ 3∏ (0+u) (predissociation level), was measured by the tunable dye laser and isotope shifts were observed. The molecules selectively excited by the irradiation of the dye laser were predissociated and reacted with hydrogen iodide (HI) to give hydrogen bromide (HBr). The obtained over-all maximum separation factor was 1.02. If the quantity of HBr produced by the dark reaction was subtracted from that of total HBr product, the maximum separation factor is 1.15. This is almost in agreement with the separation factor 1.2 estimated from the limited line width of the laser.
Nematic liquid-crystal prism cells are made, in which liquid-crystal molecules are aligned homogeneously. Relationship between incident angles and deflection angles of the prism cells are investigated for ordinary and extraordinary rays (λ=632.8nm). Combining a TN (twisted nematics) cell to the prism cell, the light beam deflection can be achieved by switching the direction of polarization by the TN cell. In the n-fold multilayered structures made by stacking the prism cells and the TN cells, 2n directions of deflection can be selected. Two or more points can be displayed simultaneously provided that the applied voltages are adjusted to the value around the threshold voltage in each TN cell. Utilizing 4 stages of the prism cells and the TN cells, 4×4 points display is demonstrated. The light deflection system described in this article is characterized by its low operation voltage. Matching of refractive indices between the liquid-crystal and the substrate glass-plate is not a necessary condition in this system.
A radio wave imaging method is proposed, where the radio wave fields are mapped by scanning a small shielding plate in the fields. Since the electric power from the receiver decreases as the shielding plate sweeps across a radio wave field of a stronger intensity, the field pattern can be recorded by displaying the signals received by a fixed receiver. An experiment is conducted with a 10 GHz microwave, where images of planar objects are recor-ded by scanning a small aluminum plate near the objects and displaying the signals from a receiving electromagnetic horn by a CRT. Based on experimental results, applications of this imaging method to the detection of metallic objects in optically opaque dielectric materials and to the visualization of radiation fields from the microwave apparatus are discussed. Fur-ther, this imaging method is discussed from the point of view of radio wave shadowgraphy and holography also with experimental results.