Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Objective type
Patent
1998-03-11
2000-01-25
Manuel, George
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Objective type
A61B 310
Patent
active
060171227
ABSTRACT:
A flicker photometer comprises generating means (1, 8, 4) for generating two beams of light of different colors. Both beams are directed to a viewing means (190), and a subject can vary the intensity of light from one beam relative to the other. The color of the light seen by the subject is caused to alternate by a shutter (18) which is rotated about an axis by a motor, the shutter having a portion which extends non-perpendicularly relative to the axis to facilitate a compact construction of photometer. The performance of the photometer is improved by screens which scatter light before it reaches the subject. A first of the screens reflects light from one beam, whilst a second screen transmits light from the other. If light of wavelengths to which the eye is less sensitive is passed through the second screen, whilst light of a wavelength to which the eye is more sensitive passes through the first screen, the screens help to make it practicable for the generating means to use a single lamp (1) to produce the light for both beams.
REFERENCES:
patent: 4454882 (1984-06-01), Takano
patent: 4963724 (1990-10-01), Neumann
patent: 5506633 (1996-04-01), Sperling
Bone, "Comparison Of Macular Pigment Densities In Human Eyes", Vision Res., vol.11, 1971, pp. 1057-1064.
Van Esch, "Spectral Sensitivity and Wavelength Discrimination of the Human Peripheral Visual Field", J. of Opt. Soc. Of Am., vol. 1, No. 5, May 1994, pp. 443-450.
Hasche, :Ein Automatisches Synchronisiertes Registrier-Flimmesfotometer, Elektrotechnische Zeitschrift, vol. 25, No. 6, Mar. 20, 1973, pp. 122-123.
Bone Richard Andrew
Huang Wenlue
Landrum John Thomas
Orta Carlos Manuel
Manuel George
The Howard Foundation
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