Dual light valve system with selective decoupling of light valves

DETAILED DESCRIPTION What is claimed is: 1.
Apparatus for preventing undesired correction of an atmospheric reference wavefront in a dual light valve, laser wavefront correcting system comprising: a main aberration correction system having a first liquid crystal light valve operatively coupled to a feedback portion for causing the liquid crystal light valve to adjust its reflective properties in a manner to drive to zero the atmospheric aberrations in a reference wavefront impinging thereon; an auxiliary correction system having a second liquid crystal light valve operatively coupled to a second feedback portion for causing the second liquid crystal light valve to adjust its reflective properties in a manner to store a phase correction pattern derived from the first liquid crystal light valve; a main laser coupled to direct a beam to the first liquid crystal light valve and to the feedback system associated therewith for controlling the first liquid crystal light valve to correct the wavefront of an atmospheric reference beam by driving the phase errors in said wavefront to zero; means for directing said beam to the first liquid crystal light valve and thereafter by reflection to the second liquid crystal light valve and to the feedback portion of the auxiliary correction system for writing the phase correction pattern corresponding to the first liquid crystal light valve on the second liquid crystal light valve; and means for selectively decoupling the auxiliary correction system from the main aberration system to prevent the auxiliary correction system from modifying the atmospheric aberration correction performed by the main aberration correction system.
2.
The apparatus of claim 1 wherein the selectively decoupling means comprise means for separating the bandwidth of the auxiliary correction system from the bandwidth of the main aberration correction system.
3.
The apparatus of claim 2 wherein said last-mentioned means include an added element installed in the second feedback portion which is coupled to the second liquid crystal light valve of the auxiliary correction system to slow the response of said second liquid crystal light valve below the range of correction of the atmospheric compensation developed by the first liquid light valve