Apparatus for testing twilight vision and blinding sensitivity

Details Apparatus for testing twilight vision and blinding sensitivity Apparatus for testing twilight vision and blinding sensitivity

1981-11-04

1983-09-13

Corbin, John K.

Optics: eye examining, vision testing and correcting

Eye examining or testing instrument

Subjective type

351243, A61B 302

Patent

active

044038429

ABSTRACT:
An apparatus for testing twilight vision and blinding sensitivity includes a housing having openings in opposite sides thereof, a person to be tested being able to look through the housing along a line of sight extending through both openings. A filter is provided for one of the openings to limit external light entering such opening. A concave mirror is arranged in the housing with its optical axis normal to the line of sight, and a semi-transparent mirror is arranged at the intersection of and at 45.degree. angles with respect to the line of sight and the mirror optical axis. A screen arranged at the focal point of the mirror is simultaneously illuminated by two projectors, a test figure being arranged in the beam of one projector and the light intensities of the two projectors being inversely proportionally controlled. Two filters are provided which can each be inserted in the beam of a respective one of the projectors to further reduce the light intensity. A headlight simulating source is arranged adjacent the field of vision on the screen and a third projector projects at least one fixation point onto the screen.

REFERENCES:
patent: 3415594 (1968-12-01), Aulhorn et al.

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