F-θ lens system

Claim 2

An F-θ lens system comprising a first lens group consisting of a first positive meniscus lens component having a concave surface on the incidence side and a second negative lens component, and a second lens group consisting of a third positive lens component and a fourth positive lens component, said lens system being so designed as to satisfy the following conditions: ##EQU4## wherein the reference symbol e I II represents distance between the principal points of said first lens group and said second lens group, the reference symbol f II designates focal length of said second lens group, the reference symbols f 1 and f 2 denote focal lengths of said first and second lens components respectively, and the reference symbols r 2 and r 3 represent radii of curvature on the image side surface of said first lens component and incidence side surface of said second lens component respectively.

Claim 3

An F-θ lens system according to claim 1 having the following numerical data: ______________________________________ r.sub.1 = -0.19353 d.sub.1 = 0.0204 n.sub.1 = 1.75925 r.sub.2 = -0.16208 d.sub.2 = 0.0159 r.sub.3 = -0.16151 d.sub.3 = 0.0218 n.sub.2 = 1.68718 r.sub.4 = -1.62215 d.sub.4 = 0.0122 r.sub.5 = -1.13249 d.sub.5 = 0.0384 n.sub.3 = 1.68718 r.sub.6 = -0.28925 d.sub.6 = 0.0039 r.sub.7 = -5.10443 d.sub.7 = 0.0531 n.sub.4 = 1.68718 r.sub.8 = -0.43119 f = 1 F/25.5 θ = 30.4° λ = 488 nm ______________________________________ wherein the reference symbol f represents focal length of the entire lens system as a whole, the reference symbol θ designates field angle, the reference symbols r 1 through r 8 denote radii of curvature on the surfaces of the respective lens components, the reference symbols d 1 through d 7 designate thicknesses of the respective lens components and airspaces reserved therebetween, and the reference symbols n 1 through n 4 represent refractive indices of the respective lens components at the wavelength λ defined in the numerical data.

Claim 4

An F-θ lens system according to claim 1 having the following numerical data: ______________________________________ r.sub.1 = -0.20722 d.sub.1 = 0.0203 n.sub.1 = 1.75606 r.sub.2 = -0.17688 d.sub.2 = 0.0159 r.sub.3 = -0.17713 d.sub.3 = 0.0240 n.sub.2 = 1.75606 r.sub.4 = -1.14172 d.sub.4 = 0.0122 r.sub.5 = -1.02500 d.sub.5 = 0.0484 n.sub.3 = 1.75606 r.sub.6 = -0.27402 d.sub.6 = 0.0041 r.sub.7 = 403.52558 d.sub.7 = 0.0522 n.sub.4 = 1.75606 r.sub.8 = -0.69286 f = 1 F/19.7 θ = 30.1° λ = 632.8 nm ______________________________________ wherein the reference symbol f represents focal length of the entire lens system as a whole, the reference symbol θ designates field angle, the reference symbols r 1 through r 8 denote radii of curvature on the surfaces of the respective lens components, the reference symbols d 1 through d 7 designate thicknesses of the respective lens components and airspaces reserved therebetween, and the reference symbols n 1 through n 4 represent refractive indices of the respective lens components at the wavelength λ defined in the numerical data.

Claim 5

An F-θ lens system according to claim 1 having the following numerical data: ______________________________________ r.sub.1 = -0.21727 d.sub.1 = 0.0245 n.sub.1 = 1.75606 r.sub.2 = -0.18765 d.sub.2 = 0.0159 r.sub.3 = -0.18590 d.sub.3 = 0.0240 n.sub.2 = 1.75606 r.sub.4 = -1.21958 d.sub.4 = 0.0122 r.sub.5 = -1.07598 d.sub.5 = 0.0524 n.sub.3 = 1.75606 r.sub.6 = -0.27778 d.sub.6 = 0.0041 r.sub.7 = 7.37933 d.sub.7 = 0.0469 n.sub.4 =1.75606 r.sub.8 = -0.82739 f = 1 F/19.7 θ = 30.1° λ = 632.8 nm ______________________________________ wherein the reference symbol f represents focal length of the entire lens system as a whole, the reference symbol θ designates field angle, the reference symbols r 1 through r 8 denote radii of curvature on the surfaces of the respective lens components, the reference symbols d 1 through d 7 designate thicknesses of the respective lens components and airspaces reserved therebetween, and the reference symbols n 1 through n 4 represent refractive indices of the respective lens components at the wavelength λ defined in the numerical data.

Claim 6

An F-θ lens system according to claim 1 having the following numerical data: ______________________________________ r.sub.1 = -0.22168 d.sub.1 = 0.0265 n.sub.1 = 1.75606 r.sub.2 = -0.19289 d.sub.2 = 0.0159 r.sub.3 = -0.18867 d.sub.3 = 0.0241 n.sub.2 = 1.75606 r.sub.4 = -1.23440 d.sub.4 = 0.0122 r.sub.5 = -1.08931 d.sub.5 = 0.0524 n.sub.3 = 1.75606 r.sub.6 = -0.27485 d.sub.6 = 0.0041 r.sub.7 = 5.15198 d.sub.7 = 0.0469 n.sub.4 = 1.75606 r.sub.8 = -0.92009 f = 1 F/19.7 θ = 30.1° λ = 632.8 nm ______________________________________ wherein the reference symbol f repesents focal length of the entire lens system as a whole, the reference symbol θ designates field angle, the reference symbols r 1 through r 8 denote radii of curvature on the surfaces of the respective lens components, the reference symbols d 1 through d 7 designate thicknesses of the respective lens components and airspaces reserved therebetween, and the reference symbols n 1 through n 4 represent refractive indices of the respective lens components at the wavelength λ defined in the numerical data.

Claim 7

An F-θ lens system according to claim 1 having the following numerical data: ______________________________________ r.sub.1 = -0.22684 d.sub.1 = 0.0245 n.sub.1 = 1.75606 r.sub.2 = -0.20559 d.sub.2 = 0.0159 r.sub.3 = -0.19284 d.sub.3 = 0.0240 n.sub.2 = 1.75606 r.sub.4 = -1.17421 d.sub.4 = 0.0122 r.sub.5 = -1.03890 d.sub.5 = 0.0525 n.sub.3 = 1.75606 r.sub.6 = -0.26935 d.sub.6 = 0.0041 r.sub.7 = 6.39726 d.sub.7 = 0.0469 n.sub.4 = 1.75606 r.sub.8 = -0.87290 f = 1 F/19.7 θ = 30.1° λ = 632.8 nm ______________________________________ wherein the reference symbol f represents focal length of the entire lens system as a whole, the reference symbol θ designates field angle, the reference symbols r 1 through r 8 denote radii of curvature on the surfaces of the respective lens components, the reference symbols d 1 through d 7 designate thicknesses of the respective lens components and airspaces reserved therebetween, and the reference symbols n 1 through n 4 represent refractive indices of the respective lens components at the wavelength λ defined in the numerical data.

Claim 8

An F-θ lens system according to claim 1 having the following numerical data: ______________________________________ r.sub.1 = -0.22612 d.sub.1 = 0.0245 n.sub.1 = 1.75606 r.sub.2 = -0.20546 d.sub.2 = 0.0159 r.sub.3 = -0.19396 d.sub.3 = 0.0240 n.sub.2 = 1.75606 r.sub.4 = -1.17926 d.sub.4 = 0.0122 r.sub.5 = -1.04560 d.sub.5 = 0.0525 n.sub.3 = 1.75606 r.sub.6 = -0.27139 d.sub.6 = 0.0041 r.sub.7 = 7.17951 d.sub.7 = 0.0469 n.sub.4 = 1.75606 r.sub.8 = -0.85199 f = 1 F/19.7 θ = 30.1° λ = 632.8 nm ______________________________________ wherein the reference symbol f represents focal length of the entire lens system as a whole, the reference symbol θ designates field angle, the reference symbols r 1 through r 8 denote radii of curvature on the surfaces of the respective lens components, the reference symbols d 1 through d 7 designate thicknesses of the respective lens components and airspaces reserved therebetween, and the reference symbols n 1 through n 4 represent refractive indices of the respective lens components at the wavelength λ defined in the numerical data.