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Crane, H. D.

Publications and source records attributed to Crane, H. D..

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Generation-V dual-Purkinje-image eyetracker

Major advances characterize the Generation-V dual-Purkinje-image eyetracker compared with the Generation-III version previously described. These advances include a large reduction in size, major improvements in frequency response and noise level, automatic alignment to a subject, and automatic adjustment for different separation between the visual and optic axes, which can vary considerably from subject to subject. In a number of applications described in the paper, the eyetracker is coupled with other highly specialized optical devices. These applications include accurately stabilizing an image on a subject's retina; accurately simulating a visually dead retinal region (i.e., a scotoma) of arbitrary shape, size, and position; and, for clinical purposes, stabilizing the position of a laser coagulator beam on a patient's retina so that the point of contact is unaffected by the patient's own eye movements.

Crane, H. D.↗
NASA NTRS1973

Training the visual accommodation system.

Polarity cue for visual accomodation response of trained subjects to target motion direction change, considering retinal image blur and feedback relation

Cornsweet, T. N.↗
NASA NTRS1972

Projections of scan patterns on human retina

Fundus camera tracks eye movements by using camera optics with the aid of an inverted system. Camera provides a flying-spot circular scanning light source in the normal film plane and a broadband photodetector in position normally occupied by light source.

Kelly, D. H.↗
NASA NTRS1972

Experimental study of visual accommodation

A summary report of a research effort related to the human visual accommodation system is presented. A theoretical study of the accommodation system was made. Subsequent effort was aimed at the development of specialized instrumentation for experiments designed to lead to understanding the nature of the control system in human accommodation. The necessary instrumentation consisted primarily of: (1) an automatic optometer to measure the state of eye focus, (2) a focus stimulator device to control the apparent optical distance to any target, and (3) a two-dimensional eye tracker. The concepts and designs of the first two instruments have been published in the open literature, but this report contains the first detailed treatment of the Purkinje eye tracker developed under this program. The report also discusses an accommodation lag model to explain the ability of the eye to apparently know the polarity of focus error even though the blur on the retina is to a first-approximation an even function. The interaction of the accommodation and eye movement systems is also discussed, as is the ability to train the visual accommodation system to a surprisingly responsive condition in only a few hours of training.

Cornsweet, T. N.↗
NASA NTRS1972

Scanning technique for tracking small eye-movements

Scanning technique images spot of blue light on fundus, measures variations in reflectance of spot and compares reflectance pattern with a stored reference pattern. Method then converts the difference from stored pattern into infrared eye motion.

Kelly, D. H.↗
NASA NTRS1970

Automatic optometer operates with infrared test pattern

Refractive strength of human eye is monitored by optometer that automatically and continuously images infrared test pattern onto the retina. Condition of focus of the eye at any instant is determined from optometer settings needed to maintain focus of the pattern on the retina.

Cornsweet, T. N.↗
NASA NTRS1970

Ocular-focus stimulator

Ocular focus stimulator with provision for optical distance change between object and observer without brightness and visual angle variation

Cornsweet, T. N.↗