Abstract: A puff tonometer in which the eyepiece and objective lens form a simple telescope which is capable of presenting to the user an in-focus image of distant objects, as well as an image of light reflected by an eye under test at close quarters when viewed through the eyepiece. A Pechan-Schmidt prism inverts the image and presents to the user an image of the patient's eye which is correctly oriented and handed in a vertical and horizontal sense. The focal length of the eyepiece typically lies in the range 62-100 mm, preferably 80 mm.

Abstract: A puff tonometer includes two light sources located at diametrically opposite points, preferably equidistant from the optical axis of the objective lens assembly of the tonometer. The sources are arranged to direct light forwardly of the tonometer such that, in use, and when positioned close to a patient's eye under test, light from the two sources, after reflection by the anterior corneal surface of the eye under test, will be imaged by the objective lens assembly of the tonometer, to appear as two small areas of light in the field of view.

Abstract: A puff tonometer which includes an object at a point in the optical path of light from a source of light in the tonometer, typically near to the source, such that an in-focus image of the object will be formed in the user's field of view when the tonometer is at the critical distance from an eye under test at which the automatic air pulse generating means will be triggered by light reflected from the eye forming an in focus image of a mask on a plurality of photoelectric sensors. A second object may be located in the same region of the tonometer as the first object, but in a plane which is spaced from the plane containing the first object, whereby its image will come into focus in the field of view just before the image of the first object comes into focus, as the unit is moved slowly towards the patient's eye.

Abstract: An apparatus for providing a two-dimensional image of a three-dimensional object illuminates the surface of the object using an illumination source. Portions of the surface are imaged through an aperture in a plate onto a portion of a matrix sensor. The object is rotated about its principle axis while being simultaneously translated, and, at the same time the aperture is also rotated. By synchronizing these translational and rotational movements, successive portions of the object surface can image onto respective successive portions of the matrix sensor, thereby providing an improve two-dimensional image of the surface of the object.