Combined shearing interferometer and hartmann wavefront sensor

Patent · Tue May 21 04:00:00 EDT 1985

OSTI ID:6384265

Hutchin, R A

A sensitive wavefront sensor combining attributes of both a Hartmann type of wavefront sensor and an AC shearing interferometer type of wavefront sensor. An incident wavefront, the slope of which is to be detected, is focussed to first and second focal points at which first and second diffraction gratings are positioned to shear and modulate the wavefront, which then diverges therefrom. The diffraction patterns of the first and second gratings are positioned substantially orthogonal to each other to shear the wavefront in two directions to produce two dimensional wavefront slope data for the AC shearing interferometer portion of the wavefront sensor. First and second dividing optical systems are positioned in the two diverging wavefronts to divide the sheared wavefront into an array of subapertures and also to focus the wavefront in each subaperture to a focal point. A quadrant detector is provided for each subaperture to detect the position of the focal point therein, which provides a first indication, in the manner of a Hartmann wavefront sensor, of the local wavefront slope in each subaperture. The total radiation in each subaperture, as modulated by the diffraction grating, is also detected by the quadrant detector which produces a modulated output signal representative thereof, the phase of which relative to modulation by the diffraction grating provides a second indication of the local wavefront slope in each subaperture, in the manner of an AC shearing interferometer wavefront sensor. The data from both types of sensors is then combined by long term averaging thereof to provide an extremely sensitive wavefront sensor.

• Assignee: Itek Corporation
• Patent Number(s): US 4518854
• OSTI ID: 6384265
• Country of Publication: United States
• Language: English

Related Subjects

440300* -- Miscellaneous Instruments-- (-1989)
47 OTHER INSTRUMENTATION
ALTERNATING CURRENT
CURRENTS
DATA PROCESSING
ELECTRIC CURRENTS
ELECTROMAGNETIC RADIATION
IMAGE PROCESSING
INTERFEROMETERS
MEASURING INSTRUMENTS
PROCESSING
RADIATIONS
SHEAR
VISIBLE RADIATION
WAVE PROPAGATION