Patent GB-792662-A (GB)
Title: Improvements in or relating to optical alignment apparatus
IPC: G01B11/27
Filed: 1953-07-13
Abstract: 792,662. Optical apparatus. OPTICAL MEASURING TOOLS, Ltd.. and DIETRICH. C. F. July 7. 1954 [July 13, 1953], No. 19339/53. Class 97(1) Apparatus for aligning, with a reference axis. a carriage movable along a guideway comprises an optical system having a common optical axis at least part of which lies parallel with the guide-way to act as a reference axis upon projecting light through the system, optical elements carried by the carriage and located at points spaced apart thereon in its direction of movement, each of which elements receives projected light and thereby indicates its own position, and hence the position of the corresponding point, laterally with resnect to the reference axis, means for indicating simultaneously deviations of the points from the reference axis and means for moving the carriage to re-align the points with the reference axis. A system, Fig. 2, for aligning a carriage 50 with an axis ab comprises a lamp 16 illuminating a graticule on a prism 11 which reflects the light by way of an inclined mirror b, a lens 12, mirrors, e, d, a lens 13, a mirror a to a prism 14 carrying a reference mark, the lamp and prisms being on the carriage. The lenses 12, 13 form a unit magnification telescopic system which images the graticule on the plane of the reference mark: Any relative movement between the reference mark and the image of the graticule provides a measure of movement of a point P, mid-way between the prisms 11, 14 transverse to the axis ab. A similar system comprising prisms 21, 24 in conjunction with mirrors a, b, c, d. lenses 12, 13 and lamp 26, provides a measure of any such movement of the point Q. Both reference marks and graticule images are viewed simultaneously by a miscroscope 35 in conjunction with lenses 17, 27, mirrors 18, 28 and a prism 31. In a modification of this system the mirrors a, b, c. d and the lenses 12, 13 are replaced by concave mirrors at the ends of the axis a, b having their axes aligned with that axis. Systems as described above are used in the apparatus of Fig. 5. A base 60 carries guides 61, 62 for a carriage 63 movable bv a motor controlled by push buttons 69 and a fine adjustment device 79. The carriage supports a hollow arm 76 containing a scale 77 imaged by a lens 81 on to a screen 82 to indicate the longitudinal carriage movement, the lens and screen being supported by a bracket 80 on the base. Mirrors corresponding to a, b, c, d and lenses corresponding to 12. 13 are mounted in the base and the remaining elements of a system as described are mounted in the carriage 63, the images .being observed in a .microscope 135. Fine adjustment of the carriage 63, transversely of the guides 61, 62, is effected at the two ends of the carriage by knobs 136, 137. The carriage 63 has transverse guides for the cross slide 65 actuated by a handle 64 and fine adjustment 86, scale indications of the movement being projected on to screen 83. Small transverse adjustments of the cross slide at. its two ends are produced by knobs 237, 238 in accordance with indications of an optical system, as described above, carried partly in the carriage 63 and partly in the cross slide 65, the images being observed through a microscope 235. The cross slide supports a table 67 rotatable by a handle 66 with a fine adjustment 85, indications of the rotation being projected on to a screen 84. An object 68 on the table 67 may be viewed through a microscope carried from the base 60 on a column 70 and comprising an eyepiece 75, with graticules in a casing 74, and a triple nose piece 73.