Hypersonic Re-Entry Optical Transfer Equations And Photographic Techniques

Radiation transfer equations applicable to various types of imaging instruments used against distant sources are presented. Emphasis is placed on measurements against point and line radiators made with instruments yielding image spectra. Framing and streaking cameras are discussed in terms of the overall transfer functions of the instrument and sensor. Calibration techniques used for absolute intensity measurements are shown to yield data within a factor of two of the actual value in most cases. The instruments described are of specific use in optical radiometry against bodies penetrating the earth's atmosphere in the hypervelocity regime, and are equally applicable to measurements in a ballistic range. For the problem of tracking these fast-moving objects, imaging instruments are preferred to point detector devices.