Ultra-wide angle F-.theta. lens system
AssigneeCopal Electronics Co., Ltd.
InventorToshifumi Uetake
Life of this patent
Estimating the term…
Abstract
An ultra-wide angle f-.theta. lens system comprising, in the order from the light beam deflector side, a first lens component having positive power, a second lens component having negative power, and a third lens component having positive power, the ultra-wide angle f-.theta. lens system being arranged to have an ultra-wide scanning angle widened to .+-.45.degree. and exhibiting an imaging performance of laser beam waist close to the diffraction limit in spite of the fact that the f-.theta. lens system comprises a small number of lenses.
Claims6
An ultra-wide angle f-.theta. lens system comprising, in the order from the light beam deflector side, a first lens component having positive power, a second lens component having negative power, and a third lens component having positive power, said ultra-wide angle f-.theta. lens system fulfilling the following conditions:
- 0.19F.sub.0 .ltoreq.L.ltoreq.0.23F.sub.0 ( 1)
- -0.35.ltoreq.R.sub.2 /F.sub.0 ( 2)
- 1.60.ltoreq.n (3)
- -5.0F.sub.0 .gtoreq.F.sub.12 ( 4)
- where, reference symbol L represents the overall length of the lens system as a whole, reference symbol F.sub.0 represents the focal length of the lens system as a whole, reference symbol R.sub.2 represents the radius of curvature of the surface on the light beam deflector side of the first lens component, reference symbol n represents the refractive index of the third lens component for the wavelength of 780 nm, and reference symbol F.sub.12 represents the total focal length of the first and second lens components.
Dependencies are inferred from the claim text.