ABSTRACT
Various photographic recording techniques are concerned with the ultra-violet (UV) spectral region, principally 200–100 nm. In comparison with infrared (IR) photography, there are practical difficulties which are principally due to the spectral transmission of the optical materials available. Techniques of UV reflectance photography, where the subject is illuminated by a UV-rich source, such as electronic flash, which also emits strongly in the visible and IR regions, require that a ‘black glass’ optical filter is used over the camera lens. A UV lens must be chromatically corrected or achromatized, in particular for the UV region and the visible, so that visual focusing will be correct for subsequent UV imagery. The use of UV-sensitive video tubes with suitable lenses and a quartz faceplate to give real-time UV visualization and recording was described by R. Marshall. Several camera systems have had a UV lens available in the lens ranges offered, but few are available.
