Patent GB-886060-A (GB)
Title: Improvements relating to panoramic cameras
IPC: G03B37/02
Filed: 1960-02-02
Abstract: 886,060. Panoramic cameras. PERKINELMER CORPORATION. Feb. 2, 1960 [Feb. 6, 1959], No. 3682/60. Classes 97(1) and 98(1). A panoramic camera comprises a double sided reflector mounted for rotation about an axis in the plane of the reflector, two identical lens systems, arranged similarly one on each side the reflector, two slits, one in the focal plane of each lens system, a shutter in the optical path between each lens system and each slit, and means for continuously rotating the reflector and for continuously moving a length of photographic film past the slits at a linear speed equal to twice the angular speed of the reflector multiplied by the focal length of the lens systems when photography by means of light reflected from the reflector so as to pass through the lenses, shutters and slits is taking place. The camera is described for use in aerial photography, in which case it is mounted above windows such as 36-38 in an aircraft, the direction of motion of which is perpendicular to the plane of Fig. 1. As the double sided prismatic reflector 41 rotates about a spindle 26, strips of ground are scanned from horizon to horizon and images of successive strips are formed alternately at exposure slits 18 and 19 by way respectively of lens systems 27, 31, mirrors 28, 32, shutters 34, 35 which are operated in synchronism with the rotating reflector 41, and field lenses 29, 33. Film 10 is fed continuously past the exposure slits from a spool 11 by means of rollers as shown, 14 and 23 of which are driven, metering units 15 and 24 being provided to control the rate of film feed and film tension. Due to unequal intervals of time between the recording of the nadir points in successive strips-which defect is inherent in the optical system as described and would lead to uneven spacing of the image frames along the length of film 10-the two exposure slits 18 and 19 are separated by a distance along the film path equal to twice the focal length of the lens 27 or 31 times the angle (in radians) at which each of the lenses 27 and 31 is inclined to the horizontal. A further result of said unequal intervals is that there is uneven overlap of the ground scanned between successive strips. To correct for this defect the lens 27 is displaced slightly backward in the direction of flight compared with lens 31. To compensate for the movement of the image in the exposure slits arising from the motion of the plane relative to the ground, the lenses 27 and 31 are moved backwards and forwards in the direction of flight with a simple harmonic motion which is synchronized with the rotating reflector 41. Mechanism for controlling the various operations is shown in Fig. 4, and includes a motor 44 which drives the feed roller 14 by way of a shaft 45. A shaft 48 is driven by way of bevel gears 46, 47 and rotates the spindle 26 of the reflector 41 by way of further bevel gears 49, 51. The lenses 27, 31 are mounted for sliding movement in guides 67, 66 and are coupled to shaft 48 for simple harmonic motion by way of bevel gears 53-55 and pin-and-slot connections such as shown at 61, 63.