GB693138A - Improvements in photogrammetric projection apparatus - Google Patents

Abstract

693,138. Photogrammetric apparatus. KELSH, H. T. March 28, 1951, No. 7182/51. Class 97 (ii). A projecting unit has a diapositive mount, a projection lens and a light beam projector angularly movable to direct a beam of light through a small area of the diapositive and through the projection lens which is coupled to the projector so as to be moved axially, as the projector is moved, to compensate radial distortions produced by the lens in the image of the selected diapositive area. In the form shown, each of two projectors is carried on rails 14 by means of a frame 16 within which a block 17 is adjustably mounted. A tube 23 is suspended below the projection lens on a yoke whose ends 28, 29 are pivoted to a gymbal ring 30 on pivots, one of which is shown at 33, in the central aperture in the block 17. A ring 18, also carried on the block 17, supports the lower end of a hollow truncated pyramid at the upper end of which the transparency is carried. A bent arm 22 is secured to the tube 23 and carries the light beam projector at its upper end and a counter weight 221. The projection lens housing 38 is flanged at 39 and three screws 40, 41, 42, each with a spring under its head, pass through the flange and are secured in a block 35 supported by a bridge 36 from the member 17. A member 50, with a spherical lower surface, is seated in the member 35 and carries a downwardly projecting rod 66 linked to the tube 23 to move parallel with it. The member 50 has an upper cam surface 51 with a follower 52 on a yoke, pivoted 60, 61 and on which bear pins 62, 63 projecting from the lens mount. Movement of the tube 23 thus causes axial lens adjustment determined by the cam surface 51. The tubes 23 of the two projectors are each secured to rods connected to the plotting device beneath so that their axes are conveyed thereon.