Patent GB-519201-A (GB)
Title: Improvements in or relating to optical measuring or testing apparatus
IPC: G02B21/00
Filed: 1938-09-17
Abstract: 519,201. Optical testing-apparatus. KAPELLA, Ltd., WARMISHAM, A., REASON R. E., and CLIFFORD, T. W. Sept. 17, 1938, No. 27139. [Class 97 (i)] Apparatus for testing profiles of screw threads &c. comprises a work support, an optical head carrying means for defining a section surface of the profile and for projecting an image of the profile, and means whereby the support and head may be relatively rotated about two mutually perpendicular axes ; means for translating the head in a direction parallel to one axis and for translating the support in three directions may be provided, and the apparatus may be, constructed with the rotational and translatory movements interchanged. The apparatus may embody features described in Specifications 498,377, 498,378, 498,382, 498,419, 498,420, and 498,458, and, as shown in Fig. '2, comprises a hood D rotatable about a fixed shaft B and carrying an optical head E rotatable about an axis perpendicular to that of the shaft B, the two axes being coplanar and intersecting at a " zero point" C. The position of the work A<1> is adjustable by means of three slides A<2>, A<3>, A<4> and the hood D comprises a portion F which is adjustable on a slide D' in a direction parallel to the axis of the head E. Operating means, scales &c. and a counterweight D<1> are provided in connection with the hood and optical head, and are described in detail ; a fixed flat surface B<3> at right angles to the axis of the shaft B is also provided to aid in locating the object under examination. Fig. 3 is a sectional elevation of the head E, perpendicular to that of Fig. 2, showing the optical systems &c. The illuminating system is contained in a casing N secured to the head E, and may be as described in Specification 498,377, or may be modified by the provision of a stop plate O, Fig. 10, movable to either of extreme positions along the knife edges N<1>, N<2> thus enabling images of the knife edges to be brought either on to two flanks of one tooth of a wheel under examination or on to the flanks of two consecutive teeth. The projection system may be as described in Specification 498,419 and is contained in a unit H secured to a rotor G carried on bearings E<3>, E'. The image is received on a screen or photographic plate K<2> in a fixed position in a plate box J. The plate or screen is carried in a slide K insertable through an opening J<2> and pressed by a spring J<5> against a roller J<4> ; the plate is itself pressed against three feet J<6> by a spring K' in the slide the slide shutter K' has been withdrawn. Direct viewing of the image on the screen may be effected by an eye piece L and a reflector L<1>, and the image of an illuminated graticule in a housing L<3> may be superimposed on the screen image with the aid of a semi-transparent reflector L<2>. A sliding shutter M may be operated through a lever M<1> &c. by a push rod M<6>. A modification is described in which the work table is carried by three slides on an arm about the shaft B, the hood being incapable of rotation about this shaft. Specification 519,224 also is referred to.