GB1374295A - Light beam homogenizer - Google Patents

Abstract

1374295 Optical ranging HEWLETTPACKARD CO 23 Dec 1971 [18 Jan 1971] 59953/71 Heading H4D In an optical range detecting arrangement, Fig. 1, in which a light emitting diode (LED) 10 is driven to emit a modulated light beam or a pulse, the phase of the beam or timing of the pulse will vary across the radiating surface 28 of the diode such that a phase comparison at 26 between the modulations of the driver 12 and that of the received reflected beams gives a range indication varying in dependance on where the reflector 22 is in the cross-section of the beam, One way of overcoming this source of range uncertainty is to spread the light emitted from any point of surface 28 over the whole crosssection of the beam. This is done by a light beam homogenizer 34, Fig. 2, e.g., consisting of a glass light prism Fig. 3, exactly covering the diode 10 and internally reflecting and dispersing the light emitted by the diode surface 28. The light emitting surface 40 of the prism may be frosted. A highly polished hole in a metal sheet may be used for the homogenizer.