Wafer level optical packaging system, and associated method of aligning optical wafers

Abstract

An optical system has a first relief-type diffraction grating fiducial, or alignment mark, on a transparent surface of a first optical wafer or plate, the grating arranged to deflect light away from an optical path and appear black. The first wafer may have lenses. The first fiducial is aligned to another fiducial on a second wafer having further optical devices as part of system assembly; or the fiducials are aligned to alignment marks or fiducials on an underlying photosensor. Once the optical devices are aligned and the wafers bonded, they are diced to provide aligned optical structures for a completed camera system. Alternatively, an optical wafer is made by aligning a second relief-type diffraction grating fiducial on a first master to a first relief-type diffraction grating fiducial on an optical wafer preform, pressing the first master into a blob to form optical shapes and adhere the blob to the optical wafer preform.