8 January 1996 Ophthalmoscope with microchannel image intensifier tube
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Abstract
Since 1851, the image quality of ophthalmoscopes has improved dramatically. Moreover, during this period the intensity of light used in ophthalmoscopy also has increased, but the exact limits of transient light damage at high light levels are unknown. Therefore, we have developed an instrument which functions as a low light level ophthalmoscope and ocular fundus camera. The basic structure is similar to the von Helmholtz ophthalmoscope. The beamsplitter is built of a thin glasplate. The fundus is illuminated through the outer part of the pupil. The cornea reflection is suppressed by ring-shaped illumination and orthogonal polarizers in the illumination and observation beam path. The microchannel image intensifier tube has a luminous gain of between 30,000 and 70,000 lm/lm. The image of the fundus can be observed at the fluorescent screen of the tube. The images presented by the new type ophthalmoscope allow an oriented examination of the fundus. In particular, the optic nerve and adjacent retinal vessels can be viewed with drastically reduced illumination levels compared to conventional ophthalmoscopes. During examination no mydriasis is required and the patient does not experience dazzle. The main range of applications are patients with light sensitive fundi or dazzle-sensitive eyes.
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Franz Heller, Franz Heller, U. M. Mayer, U. M. Mayer, Th. Fickenscher, Th. Fickenscher, Bernard Schmauss, Bernard Schmauss, } "Ophthalmoscope with microchannel image intensifier tube", Proc. SPIE 2629, Biomedical Optoelectronics in Clinical Chemistry and Biotechnology, (8 January 1996); doi: 10.1117/12.229524; https://doi.org/10.1117/12.229524
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