Based on photoconductive and photovoltaic effects of Semiconductors, a variety of infrared detectors such as InSb, GeAu and HgCdTe have been developed and widely used in industrial application, medical examination, weather observation and pollution measurement. To extend spectrum ranges, we are now studying infrared detectors using new materials such as PbSnTe. In this paper, we have reported the outlines of InSb, GeAu and HgCdTe infrared dete-ctors. The problems of the detectors may be summarized into five points, including (1) detector housing, (2) detector element sensitivity, (3) time constant, (4) cooling of element and (5) spectral response. Binary semiconductors, Hg1-xCdxTe and Pb1-xSnxTe, have composition-dependent energy gaps which can be made arbitrarily small according to the proposed band model, The unique structure of the energy bands together with the ease in producing single crystals of excellent homogeneity and good quality have made these alloys particularly useful for long wavelength infrared detectors as well as lasers. As described above, HgCdTe and PbSnTe crystals provide very interesting characteristics and are the most suitable materials for infrared detectors. A great many applications of HgCdTe and PbSnTe detectors may be expected in the near future.
Utilization of LNG Cold is important from the view-point of saving energy since the amount of LNG used will be more increased in the future. So far only a part of the cold is used for an air separation plant and a super freezing warehouse in our country. Studies on other new applications like, for example, crushing of scrapped metals and tires at low temperature are being made by many engineers and some of them have been proved to be technically possible, though economic or other terms are not satisfactory. Therefore it is expected that utilization of LNG cold will go towards wide and large scale combination of such processes as storage, handling and distribution of foods and garbage disposition. This affords profits which are not available if those undertakings are schemed individually.