Patent ID: 7286285

Claim:
A surgical microscope comprising: a main objective for viewing an object field; a laser light source emitting a laser beam; a diffractive element arranged after the laser light source for splitting the laser beam into a zero-order beam and a pair of first-order beams; a deflection element arranged after the diffractive element and before the main objective to receive the zero-order beam from the diffractive element and direct the zero-order beam through the main objective to non-destructively illuminate the object field; a sensor arranged to measure the intensity of one of the pair of first-order beams, wherein the measured first-order beam has not interacted with an object being observed, to provide information regarding the intensity of the zero-order beam and the intensity of the other of the pair of first-order beams; and an eyepiece tube through which the object field illuminated by the zero-order beam is visually observed by a user of the surgical microscope.