Laser optometer incorporating the Badal principle

The refractive state of the eye can be accurately determined while performing a visual task by introducing the diverged beam of a laser, reflected from a moving drum, into the visual field. The direction of the apparent motion of the resultant interference pattern is a direct indicator of refractive state. By incorporation of the Badal principle into the optical system, a measurement can be completed within approximately 30 sec. The advantage of this method over other techniques is that it permits evaluation of refractive state but does not itself influehce the magnitude of accommodation. A number of applications of this principle are cited.