Patent GB-662940-A (GB)
Title: Improvements in or relating to optical apparatus for the examination of the human eye
Inventor: BINSTEAD HUGH CECIL
IPC: A61B3/00
Filed: 1949-01-25
Abstract: 662,940. Eye examining apparatus. ALLIED INSTRUMENT MANUFACTURERS, Ltd. Jan. 19, 1950 [Jan. 25, 1949], No. 2033/49. Class 97 (i). Optical apparatus for the examination of the human eye comprises a head-rest for locating the eye to be examined at an object position, a microscope for observing the object position mounted on a bracket rotatable about an axis approximately aligned on the object position, the optical axis of the microscope being approximately normal to said axis of rotation, and means for illuminating the object position also rotatable about said axis of rotation and including an aperture, a source of light for illuminating the aperture and an objective for focusing an image of the aperture on the object position, the optical axis of such objective being approximately parallel to the axis of rotation and the illuminating beam from the objective being deflected to the object position by a small reflector which lies close to but just clear of the path of movement of the microscope. The apparatus shown comprises a head-rest A supported by columns A<SP>1</SP> on a table B. A platform E is carried on the table B by two freelyrotatable balls and by a roller C pivoted to a bracket G<SP>1</SP> which is rotatable in a member G<SP>2</SP> attached to the platform so that the latter can be moved horizontally to align the axis of a spindle C with the eye to be examined. The spindle C is slidable in a sleeve D mounted on the platform and is movable vertically by manual operation of a finger-wheel F which is connected to a bracket C<SP>1</SP> on the spindle by bevel-gears F<SP>2 </SP>and a threaded rod F<SP>1</SP>. The weight of the spindle and the bracket G<SP>1</SP> is partially supported by a spring D<SP>1</SP>, which abuts the upper end of the spindle and the lower end of sleeve D. A bracket K<SP>1</SP>, which can be clamped to the spindle by a screw L<SP>1</SP>, is rotatable about the spindle and carries a housing K<SP>2</SP> enclosing a light source K<SP>3</SP> illuminating an aperture M, a focused image of which is formed by an objective K<SP>5</SP> and directed by a mirror K<SP>7</SP> on to the eye. A bracket J<SP>1</SP>, which can be clamped to the spindle by a screw L2 and, if desired, to the bracket K<SP>1</SP> by a screw L3, is also rotatable about spindle C and carries a microscope J. The objective K<SP>5</SP> is mounted for axial adjustment in a housing K<SP>6</SP> which threads on to housing K<SP>2</SP> and the aperture M is formed by members M<SP>3</SP>, M<SP>4</SP>, Fig. 5, which are spring- urged outwardly. Cam surfaces on the outer edges of these members co-operate with pins on a rotatable collar Ml to vary the width of the slit aperture M. A member M<SP>5</SP> provided with cam surfaces co-operating with pins on another collar M<SP>2</SP> is movable across aperture M to align one of the three apertures M<SP>6</SP>, M' and M<SP>8</SP> in the upper surface thereof with the aperture M. The apertures M', M<SP>8</SP> are circles of different radii and the aperture M<SP>6</SP> presents no obstacle to the passage of light to aperture M so that it is possible to provide a slit aperture of any width or a circular aperture of one or other of two radii. The lamp housing K<SP>2</SP> is rotatable in the bracket K<SP>1</SP> and is held in adjusted position by a spring-loaded detent; the reflector K<SP>7</SP> is carried by a collar freely rotatable about the lamp housing K<SP>2</SP> and may remain stationary when the lamp housing is rotated.