Patent ID: 7585079

Claim:
An optical imaging method, comprising the following steps: providing a light source, a first lens set, a second lens set, an imaging device and a projection lens set; converging a light beam from the light source to be a light spot in a first position to pass through the first lens set, the second lens set, the imaging device and the projection lens set, wherein the light spot is imaged in a first relay position via the first lens set and is imaged in a second lens set via the second lens set, the converged light beam is projected on a screen via the imaging device and the projecting lens; defining a first optical path along which the light beam travels from the first position to the principal plane of the first lens set; defining a second optical path along which the light beam travels from the principal plane of the first lens set to the first relay position; defining a third optical path along which the light beam travels from the first relay position to the principal plane of the second lens set; defining a fourth optical path along which the light beam travels from the principal plane of the second lens set to the second relay position; setting the length of the first optical path to be longer than twice the focal length of the first lens set; and setting the length of the fourth optical path to be longer than twice the focal length of the second lens set.