Patent ID: 7327508

Claim:
A display device using a light modulator and having an improved numerical aperture (NA) of an after-edge lens system, comprising: an illumination lens for converting light output from a light source into linear parallel light, and outputting the linear parallel light; a diffractive light modulator for producing diffracted light beams having a plurality of diffraction orders by modulating the linear parallel light incident from the illumination lens according to an external control signal; an NA improvement unit comprising a first NA improvement mirror having a first reflection angle for reflecting + order diffracted light beams of the diffracted light beams and a second NA improvement mirror independent of the first NA improvement mirror and having a second reflection angle for reflecting − order diffracted light beams of the diffracted light beams, the first and second reflection angles being such that + order diffracted light beams reflected from the first NA improvement mirror and − order diffracted light beams reflected from the second NA improvement mirror come close to each other; a filter system for receiving diffracted light beams from the first and second NA improvement mirrors and passing only some of the diffracted light beams having predetermined orders, therethrough; and a projection system for focusing the diffracted light beams onto an object and allowing the focused diffracted light to scan the object.