Patent ID: 7759620
Filing Date: 2010-07-20
Classification: G02B,G03F

Abstract:
1. A method of calibrating an SLM (spatial light modulator) having a multitude of SLM elements for which linear combinations of multiple alternative calibrations produce practically indistinguishable intensity patterns on a detector in an image plane, by using analysis of multiple diffraction orders in image data projected from the SLM, the method including: projecting from the SLM at least one image of a calibration pattern onto an intensity detector in an image plane and iteratively adjusting groups of the SLM elements to produce a uniform intensity; at least occasionally during the iteratively adjusting the elements, collecting and comparing images of at least two diffraction orders on opposite sides of the zeroth diffraction order and utilizing differences between the images of the diffraction orders to guide the iteratively adjusting the elements; adjusting orientation of an intermediate reflective device in the projection optics; to direct the diffraction orders through the aperture in the Fourier plane where the zeroth diffraction order of the image would otherwise pass.