Patent ID: 8270088

Claim:
A laser combining mechanism, for use in a laser scanning microscope, which combines a first scanning optical system and a second scanning optical system onto a common optical path using a beam combiner, comprising: a first scanning optical system that includes a first scanner and a first pupil projection lens which converts light form the first scanner into a converging light flux; a second scanning optical system that includes a second scanner and a second pupil projection lens which converts light from the second scanner into a converging light flux; a beam combiner that transmits light received from the first pupil projection lens and that reflects light received from the second pupil projection lens so as to form a common optical path, said beam combiner arranged in a converging or diverging light flux; an imaging lens that receives light from the beam combiner; a first plane-parallel transparent plate, having an optical thickness equal to the optical thickness of the beam combiner, is located between the second pupil projection lens and the beam combiner and is oriented with its surface normal substantially parallel with the surface normal of the beam combiner; an astigmatism-correcting optical element is provided in the common optical path, said astigmatism-correcting optical element generating astigmatism that is equal in magnitude, but different in direction by 90 degrees, to the astigmatism generated by light from the first pupil projection lens being transmitted through said beam combiner; wherein the beam combiner is located between the first pupil projection lens and the imaging lens, and is oriented at a non-zero angle relative to the direction of the common optical path so as to combine the light from the first scanning optical system and from the second scanning optical system onto the common optical path.