Patent GB-1040665-A (GB)
Title: Improvements relating to optical scanning devices
IPC: H04N3/06
Filed: 1964-04-07
Abstract: 1,040,665. Optical apparatus. OPTISCHE INDUSTRIE "DE OUDE DELFT" N.V. April 7, 1964 [April 8, 1963], No.14346/64. Heading G2J. [Also in Division H4] focal surface, and scanning means which rotate about an axis passing through the centre of curvature of the focal surface and carries a radiation receiver upon which successive elemental portions of the image lying on a scanned line in the focal surface are projected, the scanning means scanning along a circle surrounding the lens system. Figs. 1 and 2 show a device for scanning along a line which may be carried in an aircraft to obtain an image of the terrain. This device comprises a cylindrical housing 1 having half the circumferential wall omitted to allow the radiation to pass through lens system 3 which comprises a ring- shaped part 4 consisting of two cemented halves and a spherical core 5, all the refractive surfaces having a common centre of curvature 6. The rotatable scanner comprises two tubular members 9 and 10 integral with hollow hub 11 and having lateral extensions with pin holes 12 and 13 which act as radiation receivers in this embodiment. The radiation which enters through hole 12 is deflected and focused by mirrors 19, 20, 21 and lenses 14 and 16 on to sensitive element 18 which is mounted so as to be stationary on the axis of rotation of the scanner and generates electrical signals which are fed to a display device e.g. a cathode ray tube. Motor 27 drives the scanner so that holes 12 and 13 describe alternately the same arc of 180 degrees. Plates 8 are provided to limit the width of the beams incident on the lens system. Figs. 3 and 4 show a device for scanning wide solid angles from a fixed point e.g. the upper hemisphere for flying objects. This device is similar to that in Figs. 1 and 2 except that the lens system 29 is asymmetric having its centre of curvature 30 lying in its boundary face thus causing the image forming beams to be deflected as shown. The radiation is focused by means of lenses such as 40 and 41 onto diaphragm plates 39, and a tubular shutter member 42, which has a light transmitting slot 47 and is accommodated in the hub of the scanner, ensures that only radiation from a field of view of 180 degrees is admitted to the deflecting mirror 48. Housing 32 which supports the objective 29 is mounted on a hollow arm 49 which is rotatably supported by structure 50 so as to be rotatable about an axis passing through the centre 30 of the lens system and perpendicular to the axis of rotation of the scanner. The radiation is deflected and focused by mirrors 54, 55, 56 and lenses 57 and 58 on to a sensitive element 59 which is mounted so as to be stationary in the hollow shaft 60 of arm 49. In operation the housing 32 is turned clock-wise, motor 61, at a slow rate while the scanner is rotated, motor 51 and gear 52, at a relatively fast rate and when the axis of rotation of the scanner is vertical driving mechanism 46 is activated which causes a quick half turn of the shutter member 42 so that scanning of the horizon to the left of the device can start. Between housing 32 and cover plate 34 a number of radially extending diaphragm blades 35 are mounted to limit the width of the incident beams on the lens system. The device may be modified for use with infra-red and ultra-violet radiation. A row of apertures or sensitive elements may be used so that a number of parallel lines of the focal surface are scanned simultaneously.