GB1029283A - Improvements in or relating to the control of illuminants - Google Patents

Abstract

1,029,283. Control of coloured illumination. KODAK Ltd. Feb 28,1963 [March 6,1962], No.8606/62. Headings G2C and G2J. In order to obtain uniform colour balance of an illuminant for use in colour measurement or copying, the light, after passing through appropriate colour filters, is passed successively through two "scrambling" or mirror boxes, the second being larger than the first. As shown, the light from the source is passed through a preliminary light box 1, and then through two rows of colour filters 2,3 each row comprising at least two filter elements. The light then passes through first mirror box 4, whose length is twise the diagonal of its cross-section, such that the diffusing screen 5 at its lower end is illuminated by uniformly coloured light. In order that large-area transparencies may be illuminated, second mirror box 6 is provided below the first, of larger section. This has a length equal to the diagonal of its crosssection, and uniform illumination is produced on the diffusing screen 7, below which the transparency is placed. In order to produce a higher level of illumination, four separate light sources and first mirror boxes may be used with a single common second box (Fig. 2, not shown).