Multi-beam optical system
AssigneeAsahi Kogaku Kogyo Kabushiki Kaisha
InventorTakashi Iizuka
Life of this patent
Estimating the term…
Abstract
A multi-beam optical systems forms a plurality of beam spots on an object surface to be exposed. The system includes a light source that emits a light beam having a plurality of peak wavelengths, a diffraction beam-dividing element that divides the light beam into a plurality of light beams exiting at the different diffraction angles, and a compensating optical system whose lateral magnification is inversely proportional to the wavelength of the light beam to compensate deviation of the diffraction angle of the diffracted light beams caused due to wavelength dependence of the diffraction beam-dividing element. The compensating optical system includes a diffractive lens component.
Claims9
A multi-beam optical system, comprising:
- a light source;
- a diffractive beam-dividing element that divides the light beam emitted from said light source into a plurality of light beams exiting therefrom at different diffraction angles, respectively;
- a converging element that is located at the exit side of said diffraction beam-dividing element to converge the beams exiting from said diffractive beam-dividing element;
- and
- a compensating optical system whose lateral magnification is inversely proportional to the wavelength of the light beam to compensate deviation in the diffraction angle of the diffracted light beams caused due to wavelength dependence of said diffraction beam-dividing element, said compensating optical system including at least one diffractive lens component,
- wherein the focus points of the beams formed by said converging element are located between said converging element and said compensating optical system.
A multi-beam optical system, comprising:
- a light source;
- a diffractive beam-dividing element that divides the light beam emitted from said light source into a plurality of light beams exiting therefrom at different diffraction angles, respectively;
- and
- a compensating optical system to compensate deviation in the diffraction angle of the diffracted light beams caused due to wavelength dependence of said diffraction beam-dividing element,
- wherein said compensating optical system comprises:
- a first group that has a positive power with a positive chromatic dispersion as a whole, said first group including a diffractive lens component having a negative power;
- and
- a second group that has a positive power with a negative chromatic dispersion as a whole, said second group including a diffractive lens component having a positive power.
Dependencies are inferred from the claim text.