Tunable dispersive optical system
A novel dispersion optical system based on at least one grating is provided. The pitches of the grating are linearly modulated so that the incident light is dispersed into different monochromatic light at different diffraction angles. In such a system, an order sorting filter is not required to separate the light of a selected order from the rest of unwanted overlapped order.
1. A diffraction grating, comprising:
a resilient set comprising a plurality of support units with a support unit width and first gaps with a first gap width arranged alternately;
a grating plane disposed on said resilient set and comprising a plurality of teeth with a tooth width and second gaps with a second gap width arranged alternately; and
a plurality of extending arms connecting said support units to said teeth, respectively,
wherein a modulation pitch d′ is formed by said support unit width and said first gap width, a grating pitch d is formed by said tooth width and said second gap width, and said modulation pitch d′ is greater than said grating pitch.
2. The diffraction grating according to claim 1 , wherein an energy beam illuminated from said grating plane is diffracted into a diffracted energy beam, and an equation, d(sin(α)+sin(β))=mλ, is satisfied, wherein d denotes said grating pitch, α denotes an incident angle of said energy beam, β denotes a diffraction angle of said diffracted energy beam, m denotes a diffraction order, and λ denotes a wavelength of said diffracted energy beam.
3. The diffraction grating according to claim 2 , wherein said wavelength λ of said diffracted energy beam is modulated by varying said grating pitch d.
4. The diffraction grating according to claim 1 , wherein said first gap width is modulated by deformation of said resilient set.
5. The diffraction grating according to claim 1 , wherein said modulation pitch d′ and said grating pitch d are varied with said first gap width.