Light scanning system

Claim 2

A light scanning system comprising: a light source for emitting a light beam; a first converging means for converging the light beam emitted from the light source to a linear image; a deflecting means having a deflecting surface for reflecting the converged light beam and for deflecting the reflected light beam in a direction of scan, said deflecting surface located from said first converging means at a position substantially coinciding with the location at which the line image is formed by said first converging means; and a second converging means for converging the light beam reflected from the deflecting surface of the deflecting means to a light spot on a scanning plane, the light spot moving on the scanning plane in the direction of scan as the reflected light beam is deflected by said deflecting means, said second converging means for correcting aberration in a plane parallel to the direction of scan and generating an under-corrected aberration in a plane perpendicular to the direction of scan, and said first converging means having a unidirectional convergent optical power in the plane perpendicular to the direction of scan and generating an over-corrected aberration in the plane perpendicular to the direction of scan for compensating the under-corrected aberration generated by the second converging means whereby spherical aberration is corrected by said first and said second converging means.

Claim 3

The system of claim 1, wherein the deflecting surface and the scannning plane are in conjugate relationship to each other in the plane perpendicular to the direction of scan.

Claim 4

The system of claim 1, wherein the first converging means comprises a positive cylindrical first lens, a negative cylindrical second lens and a positive cylindrical third lens sequentially arranged in the foregoing order in a direction extending away from the light source.

Claim 5

The system of claim 1, wherein the first converging means comprises a meniscus negative cylindrical first lens having a convex surface facing the light source and a positive cylindrical second lens, arranged sequentially in the foregoing order in a direction extending away from the light source.

Claim 6

The system of claim 1, wherein the second converging means comprises a spherical first lens, a spherical second lens and a third lens having at least a toric surface, arranged sequentially in the foregoing order in a direction extending away from the deflecting surface.

Claim 7

The system of claim 1, wherein the second converging means comprises a meniscus first lens having a concave surface facing the deflecting surface, a meniscus second lens having a convex surface facing the first lens and a third lens having at least a toric surface, arranged sequentially in the foregoing order in a direction extending away from the deflecting surface and toward the scanning plane.

Claim 10

The system of claim 1, having an aperture ratio of 1:49 in a plane parallel to the direction of scan, an aperture ratio of 1:49 in the plane perpendicular to the direction of scan and a half deflecting angle of 33°, wherein the first converging means comprises first, second and third lenses which are sequentially arranged in the foregoing order in a direction extending away from the light source, and the second converging means comprises fourth, fifth and sixth lenses which are sequentially arranged in the foregoing order in a direction extending away from the deflecting surface, and wherein the following conditions are substantially satisfied: __________________________________________________________________________ f.sub.p = 284.78 f.sub.p /f.sub.v = 4.15 L/f.sub.p = 0.31 f.sub.p /r.sub.12 = 0 __________________________________________________________________________ r.sub.1 = ∞ r.sub.1 '= 46.587 d.sub.1 = 2.40 n.sub.1 = 1.765299 r.sub.2 = ∞ r.sub.2 '= ∞ d.sub.2 = 14.28 r.sub.3 = ∞ r.sub.3 '= -29.870 d.sub.3 = 2.20 n.sub.2 1.510516 first converging means r.sub.4 = ∞ r.sub.4 '= ∞ d.sub.4 = 33.89 r.sub.5 = ∞ r.sub.5 '= 60.000 d.sub.5 = 3.00 n.sub.3 = 1.765299 r.sub.6 = ∞ r.sub.6 '= ∞ d.sub.6 = 51.35 deflecting surface r.sub. 7 = ∞ r.sub.7 '= ∞ d.sub.7 = 20.48 r.sub.8 =-70.606 r.sub.8 '= -70.606 d.sub.8 = 17.28 n.sub.4 = 1.765299 r.sub.9 =-77.654 r.sub.9 '= -77.654 d.sub.9 = 0.66 r.sub.10 = 354.042 r.sub.10 '= 354.042 d.sub.10 = 14.21 n.sub.5 = 1.532833 second converging means r.sub.1 = 431.786 r.sub.11 '= 431.786 d.sub.11 = 39.29 r.sub.12 = ∞ r.sub.12 '= -83.615 d.sub.12 = 18.19 n.sub.6 1.674497 r.sub.13 = -230.766 r.sub.13 '= -34.394 __________________________________________________________________________ where f p denotes a focal length of the second converging means with respect to refraction in the plane parallel to the direction of scan; f v m a focal length of the second converging means with respect to refraction in the plane perpendicular to the direction of scan; L, a length of the second converging means; r 1 through r 13 , respective radii of curvature with respect to refraction in the plane parallel to the direction of scan of the surfaces of the lenses comprising the converging means as taken in sequence in the direction away from the light source and then in the direction extending away from the deflecting surface; r 1 ' through r 13 ', respective radii of curvature with respect to refraction in the plane perpendicular to the direction of scan of each of the surfaces as taken in said sequence; d 1 through d 12 , a distance between each adjacent two of the surfaces as taken in said sequence; and n 1 through n 6 , an index of refraction at a wavelength of 790 nm of each of the lenses in said sequence.

Claim 11

The system of claim 1, having an aperature ratio of 1:49 in a plane parallel to the direction of scan, an aperture ratio of 1:49 in the plane perpendicular to the direction of scan and a half deflecting angle of 33°, wherein the first converging means comprises first and second lenses which are sequentially arranged in the foregoing order in a direction extending away from the light source, and the second converging means comprises third, fourth and fifth lenses which are sequentially arranged in the foregoing order in a direction extending away from the deflecting surface, and wherein the following conditions are substantially satisfied: __________________________________________________________________________ f.sub.p = 284.78 f.sub.p /f.sub.v = 4.15 L/f.sub.p = 0.31 f.sub.p /r.sub.10 = 0 __________________________________________________________________________ r.sub.1 = ∞ r.sub.1 '= 21.000 d.sub.1 = 4.00 n.sub.1 = 1.765299 r.sub.2 = ∞ r.sub.2 '= 17.545 d.sub.2 = 5.00 first converging means r.sub.3 = ∞ r.sub.3 '= 47.389 d.sub.3 = 3.72 n.sub.2 = 1.765299 r.sub.4 = ∞ r.sub.4 '= ∞ d.sub.4 = 79.01 deflecting means r.sub.5 = ∞ r.sub.5 '= ∞ d.sub.5 = 20.48 r.sub.6 = -70.606 r.sub.6 '= -70.606 d.sub.6 = 17.28 n.sub.3 = 1.765299 r.sub.7 = -77.654 r.sub.7 '= -77.654 d.sub.7 = 0.66 r.sub.8 = 354.042 r.sub.8 '= 354.042 d.sub.8 = 14.21 n.sub.4 = 1.532883 second converging means r.sub.9 = 431.786 r.sub.9 '= 431.786 d.sub.9 = 39.29 r.sub.10 = ∞ r.sub.10 '= -83.615 d.sub.10 = 18.19 n.sub.5 = 1.674497 r.sub.11 = -230.766 r.sub.11 '= -34.394 __________________________________________________________________________ where f p denotes a focal length of the second converging means with respect to refraction in the plane parallel to the direction of scan; f v , a focal length of the second converging means with respect to refraction in the plane perpendicular to the direction of scan; L, a length of the second converging means; r 1 through r 11 , respective radii of curvature with respect to refraction in the plane parallel to the direction of scan of the surfaces of the lenses comprising the converging means as taken in sequence in the direction extending away from the light source and then in the direction extending away from the deflecting surface; r 1 ' through r 11 ', respective radii of curvature with respect to refraction in the plane perpendicular to the direction of scan of each of the surfaces as taken in said sequence; and d 1 through d 10 , a distance between each adjacent two of the surfaces as taken in said sequence; and n 1 through n 5 , an index of refraction at a wavelength of 790 nm of each of the lenses in said sequence.

Claim 12

The system of claim 1, having an aperture ratio of 1:50 in a plane parallel to the direction of scan, an aperture ratio of 1:50 in the plane perpendicular to the direction of scan and a half deflecting angle of 30°, wherein the first converging means comprises first and second lenses which are sequentially arranged in the foregoing order in a direction extending away from the light source, and the second converging means comprises third, fourth and fifth lenses which are sequentially arranged in the foregoing order in a direction extending away from the deflecting surface, and wherein the following conditions are substantially satisfied: ______________________________________ f.sub.p = 287.66 f.sub.p /f.sub.v = 4.20 L/f.sub.p = 0.30 f.sub.p /r.sub.10 = -0.15 ______________________________________ r.sub.1 = ∞ r.sub.1 ' = 15.044 d.sub.1 = 4.00 n.sub.1 = 1.76530 r.sub.2 = ∞ r.sub.2 ' = 12.773 first converging d.sub.2 = 5.00 means r.sub.3 = ∞ r.sub.3 ' = 48.842 d.sub.3 = 3.72 n.sub.2 = 1.76530 r.sub.4 = ∞ r.sub.4 ' = ∞ d.sub.4 = 73.19 deflecting surface r.sub.5 = ∞ r.sub.5 ' = ∞ d.sub.5 = 20.00 r.sub.6 = -70.189 r.sub.6 ' = -70.189 d.sub.6 = 18.85 n.sub. 3 = 1.76530 r.sub.7 = -77.471 r.sub.7 ' = -77.471 d.sub.7 = 10.00 r.sub.8 = 369.975 r.sub.8 ' = 369.975 second converging d.sub.8 = 6.15 n.sub.4 = 1.53288 means r.sub.9 = 554.244 r.sub.9 ' = 554.244 d.sub.9 = 39.51 r.sub.10 = -1859.183 r.sub.10 ' = 78.953 d.sub.10 = 12.34 n.sub.5 = 1.67450 r.sub.11 = -227.419 r.sub.11 ' = -33.306 ______________________________________ where f p denotes a focal length of the second converging means with respect to refraction in the plane parallel to the direction of scan; f v , a focal length of the second converging means with respect to refraction in the plane perpendicular to the direction of scan; L, a length of the second converging means; r 1 through r 11 , respective radii of curvature with respect to the refraction in the plane parallel to the direction of scan of the surfaces of the lenses comprising the converging means as taken in sequence in the direction extending away from the light source and then in the direction extending away from the deflecting surface; r 1 ' through r 11 ', respective radii of curvature with respect to refraction in the plane perpendicular to the direction of scan of each of the surfaces as taken in said sequence; d 1 through d 10 , a distance between each adjacent two of the surfaces as taken in said sequence; and n 1 through n 5 , an index of refraction at a wavelength of 790 nm of each of the lenses in said sequence.

Claim 13

The system of claim 1, having an aperture ratio of 1:50 in a plane parallel to the direction of scan, an aperture ratio of 1:50 in the plane perpendicular to the direction of scan and a half deflecting angle of 30°, wherein the first converging means comprises first and second lenses which are sequentially arranged in the foregoing order in a direction extending away from the light source, and the second conveying means comprises third, fourth and fifth lenses which are sequentially arranged in the foregoing order in a direction extending away from the deflecting surface, and wherein the following conditions are substantially satisfied: ______________________________________ f.sub.p = 287.66 f.sub.p /f.sub.v = 4.13 L/f.sub.p = 0.32 f.sub.p /r.sub.10 = 0 ______________________________________ r.sub.1 = ∞ r.sub.1 ' = 38.410 d.sub.1 = 4.00 n.sub.1 = 1.76530 r.sub.2 = ∞ r.sub.2 ' = 26.065 first converging d.sub.2 = 5.00 means r.sub.3 = ∞ r.sub.3 ' = 39.264 d.sub.3 = 3.72 n.sub.2 = 1.765299 r.sub.4 = ∞ r.sub.4 '= ∞ d.sub.4 = 86.06 deflecting surface r.sub.5 = ∞ r.sub.5 ' = ∞ d.sub.5 = 20.00 r.sub.6 = -83.583 r.sub.6 ' = -83.583 d.sub.6 = 25.24 n.sub. 3 = 1.73759 r.sub.7 = -87.678 r.sub.7 ' = -87.678 d.sub.7 = 10.00 r.sub.8 = 336.361 r.sub. 8' = 336.361 second converging d.sub.8 = 6.00 n.sub.4 = 1.76167 means r.sub.9 = 432.403 r.sub.9 ' = 432.403 d.sub.9 = 39.58 r.sub.10 = ∞ r.sub.10 ' = -65.724 d.sub.10 = 12.00 n.sub.5 = 1.60659 r.sub.11 = -286.512 r.sub.11 ' = -29.803 ______________________________________ where f p denotes a focal length of the second converging means with respect to refraction in the plane parallel to the direction of scan; f v , a local length of the second converging means with respect to refraction in the plane perpendicular to the direction of scan; L, a length of the second converging means with respect to refraction in the plane perpendicular to the direction of scan; L, a length of the second converging means; r 1 through r 11 , respective radii of curvature with respect to refraction in the plane parallel to the direction of scan of the surfaces of the lenses comprising the converging means as taken in sequence in the direction extending away from the light source and then in the direction extending away from the deflecting surface; r 1 ' through r 11 ' respective radii of curvature with respect to refraction in the plane perpendicular to the direction of scan of each of the surfaces as taken in said sequence; d 1 through d 10 , a distance between each adjacent two of the surfaces as taken in said sequence; and n 1 through n 5 , an index of refraction at a wavelength of 790 nm of each of the lenses in said sequence.

Claim 14

The system of claim 1, having an aperture ratio of 1:50 in a plane parallel to the direction of scan, an aperture ratio of 1:50 in the plane perpendicular to the direction of scan and a half deflecting angle of 30°, wherein the first converging means comprises first and second lenses which are sequentially arranged in the foregoing order in a direction extending away from the light source, and the second converging means comprises third, fourth and fifth lenses which are sequentially arranged in the foregoing order in a direction extending away from the deflecting surface, and wherein the following conditions are substantially satisfied: ______________________________________ f.sub.p = 287.87 f.sub.p /f.sub.v = 3.97 L/f.sub.p = 0.30 f.sub.p /r.sub.10 = 0 r.sub.1 = ∞ r.sub.1 ' = 23.564 d.sub.1 = 4.05 n.sub.1 = 1.765299 r.sub.2 = ∞ r.sub.2 ' = 20.286 first converging means d.sub.2 = 5.06 r.sub.3 = ∞ r.sub.3 ' = 54.574 d.sub.3 = 3.77 n.sub.2 = 1.765299 r.sub.4 = ∞ r.sub.4 ' = ∞ d.sub.4 = 85.42 deflecting surface r.sub.5 = ∞ r.sub.5 ' = ∞ d.sub.5 = 25.00 r.sub.6 = -72.763 r.sub.6 ' = -72.763 d.sub.6 = 19.00 n.sub.3 = 1.76167 r.sub.7 = -77.288 r.sub.7 ' = -77.288 d.sub.7 = 10.00 r.sub.8 = 643.375 r.sub.8 ' = 643.375 second converging d.sub.8 = 11.15 n.sub.4 = 1.5119 means r.sub.9 = 2849.379 r.sub.9 ' = 2849.379 d.sub.9 = 45.00 r.sub.10 = ∞ r.sub.10 ' = -82.637 d.sub.10 = 6.00 n.sub.5 = 1.67450 r.sub.11 = -306.407 r.sub.11 ' = -34.194 ______________________________________ where f p denotes a focal length of the second converging means with respect to refraction in the plane parallel to the direction of scan; f v , a focal length of the second converging means with respect to refraction in the plane perpendicular to the direction of scan; L, a length of the second converging means; r 1 through r 11 , respective radii of curvature with respect to refraction in the plane parallel to the direction of scan of the surfaces of the lenses comprising the converging means as taken in sequence in the direction extending away from the light source and then in the direction extending away from the deflecting surface; r 1 ' through r 11 ' respective radii of curvature with respect to refraction in the plane perpendicular to the direction of scan of each of the surfaces as taken in said sequence; d 1 through d 10 , a distance between each adjacent two of the surfaces as taken in said sequence; and n 1 through n 5 , an index of refraction at a wavelength of 790 nm of each of the lenses in said sequence.

Claim 15

The system of claim 1, having an aperture ratio of 1:50 in a plane parallel to the direction of scan, an aperture ratio of 1:50 in the plane perpendicular to the direction of scan and a half deflecting angle of 30°, wherein the first converging means comprises first and second lenses which are sequentially arranged in the foregoing order in a direction extending away from the light source, and the second converging means comprises third, fourth and fifth lenses which are sequentially arranged in the foregoing order in a direction extending away from the deflecting surface, and wherein the following conditions are substantially satisfied: ______________________________________ f.sub.p = 295.12 f.sub.p /f.sub.v = 4.38 L/f.sub.p = 0.27 f.sub.p /r.sub.10 = -0.055 r.sub.1 = ∞ r.sub.1 ' = 23.636 d.sub.1 = 4.55 n.sub.1 = 1.76530 r.sub.2 = ∞ r.sub.2 ' = 20.007 first converging means d.sub.2 = 5.68 r.sub.3 = ∞ r.sub.3 ' = 46.669 d.sub.3 = 3.72 n.sub.2 = 1.76530 r.sub.4 = ∞ r.sub.4 ' = ∞ d.sub.4 = 71.86 deflecting surface r.sub.5 = ∞ r.sub.5 ' = ∞ d.sub.5 = 20.00 r.sub.6 = -65.003 r.sub.6 ' = -65.003 d.sub.6 = 8.01 n.sub.3 = 1.78506 r.sub.7 = -73.811 r.sub.7 ' = -73.811 d.sub.7 = 0.23 r.sub.8 = 607.287 r.sub.8 ' = 607.287 second converging d.sub.8 = 12.92 n.sub.4 = 1.510516 means r.sub.9 = 407.327 r.sub.9 ' = 407.327 d.sub.9 = 39.47 r.sub.10 = -5379.689 r.sub.10 ' = -117.403 d.sub.10 = 19.93 n.sub.5 = 1.72367 r.sub.11 = -167.907 r.sub.11 ' = -37.807 ______________________________________ where f p denotes a focal length of the second converging means with respect to refraction in the plane parallel to the direction of scan; f v , a focal length of the second converging means with respect to refraction in the plane perpendicular to the directio of scan; L, a length of the second converging means; r 1 through r 11 , respective radii of curvature with respect to refraction in the plane parallel to the direction of scan of the surfaces of the lenses comprising the converging means as taken in sequence in the direction extending away from the light source and then in the direction extending away from the deflecting surface; r 1 ' through r 11 ', respective radii of curvature with respect to refraction in the plane perpendicular to the direction of scan of each of the surfaces as taken in said sequence; and d 1 through d 10 , a distance between each adjacent two of the surfaces are taken in said sequence; and n 1 through n 5 , an index of refraction at a wavelength of 790 nm of each of the lenses in said sequence.

Claim 16

The system of claim 1, having an aperture ratio of 1:50 in a plane parallel to the direction of scan, an aperture ratio of 1:50 in the plane perpendicular to the direction of scan and a half deflecting angle of 30°, wherein the first converging means comprises first and second lenses which are sequentially arranged in the foregoing order in a direction extending away from the light source, and the second converging means comprises third, fourth and fifth lenses which are sequentially arranged in the foregoing order in a direction extending away from the deflecting surface, and wherein the following conditions are substantially satisfied: ______________________________________ f.sub.p = 288.01 f.sub.p /f.sub.v = 3.98 L/f.sub.p = 0.34 f.sub.p /r.sub.10 = 0.014 r.sub.1 = ∞ r.sub.1 ' = 25.637 d.sub.1 = 4.83 n.sub.1 = 1.76530 r.sub.2 = ∞ r.sub.2 ' = 21.020 first converging means d.sub.2 = 6.40 r.sub.3 = ∞ r.sub.3 ' = 48.017 d.sub.3 = 4.50 n.sub.2 = 1.76530 r.sub.4 = ∞ r.sub.4 ' = ∞ d.sub.4 = 79.87 deflecting surface r.sub.5 = ∞ r.sub.5 ' = ∞ d.sub.5 = 20.00 r.sub.6 = -68.359 r.sub.6 ' = -68.359 d.sub.6 = 12.20 n.sub.3 = 1.67450 r.sub.7 = -78.902 r.sub.7 ' = -78.902 d.sub.7 = 1.74 second converging r.sub.8 = 740.172 r.sub.8 ' = 740.172 means d.sub.8 = 23.55 n.sub.4 = 1.65903 r.sub.9 = 574.503 r.sub.9 ' = 574.503 d.sub.9 = 38.89 r.sub.10 = 20901.200 r.sub.10 ' = -149.805 d.sub.10 = 20.94 n.sub.5 = 1.63512 r.sub.11 = -161.094 r.sub.11 ' = -38.452 ______________________________________ where f p denotes a focal length of the second converging means with respect to refraction in the plane parallel to the direction of scan; f v , a focal length of the second converging means with respect to refraction in the plane perpendicular to the direction of scan; L, a length of second converging means; r 1 through r 11 , respective radii of curvature with respect to refraction in the plane parallel to the direction of scan of the surfaces of the lenses comprising the converging means as taken in sequence in the direction extending away from the light source and then in the direction extending away from the deflecting surface; r 1 ' through r 11' , respective radii of curvature with respect to refraction in the plane perpendicular to the direction of scan of each of the surfaces as taken in said sequence; and d 1 through d 10 , a distance between each adjacent two of the surfaces are taken in said sequence; and n 1 through n 5 , an index of refraction at a wavelength of 790 nm of each of the lenses in said sequence.

Claim 17

The system of claim 1, having an aperture ration of 1:50 in a plane parallel to the direction of scan, an aperture ratio of 1:50 in the plane perpendicular to the direction of scan and a half deflecting angle of 30°, wherein the first conveying means comprises first and second lenses which are sequentially arranged in the foregoing order in a direction extending away from the light source, and the second converging means comprises third, fourth and fifth lenses which are sequentially arranged in the foregoing order in a direction extending away from the deflecting surface, and wherein the following conditions are substantially satisfied: ______________________________________ f.sub.p = 291.69 f.sub.p /f.sub.v = 4.12 L/f.sub.p = 0.32 f.sub.p /r.sub.10 = 0 r.sub.1 = ∞ r.sub.1 ' = 25.357 d.sub.1 = 4.83 n.sub.1 = 1.76530 r.sub.2 = ∞ r.sub.2 ' = 21.316 first converging means d.sub.2 = 6.40 r.sub.3 = ∞ r.sub.3 ' = 49.817 d.sub.3 = 4.50 n.sub.2 = 1.76530 r.sub.4 = ∞ r.sub.4 ' = ∞ d.sub.4 = 77.99 deflecting surface r.sub.5 = ∞ r.sub.5 ' = ∞ d.sub.5 = 20.00 r.sub.6 = -67.946 r.sub.6 ' = -67.946 d.sub.6 = 11.05 n.sub.3 = 1.76167 r.sub.7 = -78.402 r.sub.7 ' = -78.402 d.sub.7 = 2.66 r.sub.8 = 743.300 r.sub.8 ' = 743.300 second converging d.sub.8 = 22.88 n.sub.4 = 1.65903 means r.sub.9 = 542.759 r.sub.9 ' = 542.759 d.sub.9 = 37.26 r.sub.10 = ∞ r.sub.10 ' = -146.768 d.sub.10 = 19.73 n.sub.5 = 1.67450 r.sub.11 = -165.713 r.sub.11 ' = -39.239 ______________________________________ where f p denotes a focal length the second converging means with respect to refraction in the plane parallel to the direction of scan; f v , a focal length of the second converging means with respect to refraction in the plane perpendicular to the direction of scan; L, a length of the second converging means; r 1 through r 11 , respective radii of curvature with respect to refraction in the plane parallel to the direction of scan of the surfaces of the lenses comprising the converging means as taken in sequence in the direction extending away from the light source and then in the direction extending away from the deflecting surface; r 1 ' through r 11 ', respective radii of curvature with respect to refraction in the plane perpendicular to the direction of scan of each of the surfaces as taken in said sequence; and d 1 through d 10 , a distance between each adjacent two of the surfaces as taken in said sequence; and n 1 through n 5 , an index of refraction at a wavelength of 790 nm of each of the lenses in said sequence.

Claim 18

The system of claim 1, having an aperture ratio of 1:50 in a plane parallel to the direction of scan, an aperture ratio of 1:50 in the plane perpendicular to the direction of scan and a half deflecting angle of 30°, wherein the first converging means comprises first and second lenses which are sequentially arranged in the foregoing order in a direction extending away from the light source, and the second converging means comprises third, fourth and fifth lenses which are sequentially arranged in the foregoing order in a direction extending away from the deflecting surface, and wherein the following conditions are substantially satisfied: ______________________________________ f.sub.p = 287.89 f.sub.p /f.sub.v = 4.24 L/f.sub.p = 0.30 f.sub.p /r.sub.10 = -0.27 r.sub.1 = ∞ r.sub.1 ' = 20.956 d.sub.1 = 4.00 n.sub.1 = 1.76530 r.sub.2 = ∞ r.sub.2 ' = 17.812 first converging means d.sub.2 = 5.00 r.sub.3 = ∞ r.sub.3 ' = 46.210 d.sub.3 = 3.72 n.sub.2 = 1.76530 r.sub.4 = ∞ r.sub.4 ' = ∞ d.sub.4 = 72.19 deflecting surface r.sub.5 = ∞ r.sub.5 ' = ∞ d.sub.5 = 20.48 r.sub.6 = -68.143 r.sub.6 ' = -68.143 d.sub.6 = 20.64 n.sub.3 = 1.78506 r.sub.7 = -80.684 r.sub.7 '= -80.684 d.sub.7 = 6.77 r.sub.8 = 918.262 r.sub.8 ' = 918.262 second converging d.sub.8 = 7.38 n.sub.4 = 1.53288 means r.sub.9 = -4001.818 r.sub.9 ' = -4001.818 d.sub.9 = 37.59 r.sub.10 = -1047.105 r.sub.10 ' = -85.234 d.sub.10 = 14.29 n.sub.5 = 1.67450 r.sub.11 = -195.914 r.sub.11 ' = -34.629 ______________________________________ where f p denotes a focal length of the second converging means with respect to refraction in the plane parallel to the direction of scan; f v , a focal length of the second converging means with respect to refraction in the plane perpendicular to the direction of scan; L, a length of the second converging means; r 1 through r 11 , respective radii of curvature with respect to refraction in the plane parallel to the direction of scan of the surfaces of the lenses comprising the converging means as taken in sequence in the direction extending away from the light source and then in the direction extending away from the deflecting surface; r 1 ' through r 11 ', respective radii of curvature with respect to refraction in the plane perpendicular to the direction of scan of each of the surfaces as taken in said sequence; and d 1 through d 10 , a distance between each adjacent two of the surfaces as taken in said sequence; and n 1 through n 5 , an index of refraction at a wavelength of 790 nm of each of the lenses in said sequence.

Claim 19

The system of claim 1, having an aperture ratio of 1:50 in a plane parallel to the direction of scan, an aperture ratio of 1:50 in the plane perpendicular to the direction of scan and a half deflecting angle of 30°, wherein the first converging means comprises first and second lenses which are sequentially arranged in the foregoing order in a direction extending away from the light source, and the second converging means comprises third, fourth and fifth lenses which are sequentially arranged in the foregoing order in a direction extending away from the deflecting surface, and wherein the following conditions are substantially satisfied: ______________________________________ f.sub.p = 298.69 f.sub.p /f.sub.v = 4.49 L/f.sub.p = 0.28 f.sub.p /r.sub.10 = -0.39 r.sub.1 = ∞ r.sub.1 ' = 21.193 d.sub.1 = 4.00 n.sub.1 = 1.76530 r.sub.2 = ∞ r.sub.2 '= 17.851 first converging means d.sub.2 = 5.00 r.sub.3 = ∞ r.sub.3 ' = 41.662 d.sub.3 = 3.72 n.sub.2 = 1.76530 r.sub.4 = ∞ r.sub.4 ' = ∞ d.sub.4 = 65.06 deflecting surface r.sub.5 = ∞ d.sub.5 = 20.48 r.sub.6 = -65.855 r.sub.6 ' = -65.855 d.sub.6 = 22.11 n.sub.3 = 1.78506 r.sub.7 = -82.458 r.sub.7 ' = -82.458 d.sub.7 = 0.00 r.sub.8 = 11290.889 r.sub.8 ' = 11290.889 second converging d.sub.8 = 9.89 n.sub.4 = 1.78506 means r.sub.9 = -1046.936 r.sub.9 ' = -1046.936 d.sub.9 = 34.50 r.sub.10 = -746.887 r.sub.10 ' = -78.255 d.sub.10 = 15.00 n.sub.5 = 1.78506 r.sub.11 = -192.977 r.sub.11 '= -36.101 ______________________________________ where f p denotes a focal length the second converging means with respect to refraction in the plane parallel to the direction of scan; f v , a focal length of the second converging means with respect to refraction in the plane perpendicular to the direction of scan; L, a length of the second converging means; r 1 through r 11 , respective radii of curvature with respect to refraction in the plane parallel to the direction of scan of the surfaces of the lenses comprising the converging means as taken in sequence in the direction extending away from the light source and then in the direction extending away from the deflecting surface; r 1 ' through r 11 ', respective radii of curvature with respect to refraction in the plane perpendicular to the direction of scan of each of the surfaces as taken in said sequence; and d 1 through d 10 , a distance between each adjacent two of the surfaces as taken in said sequence; and n 1 through n 5 , an index of refraction at a wavelength of 790 nm of each of the lenses in said sequence.

Claim 20

The system of claim 1 having an aperture ratio of 1:50 in a plane parallel to the direction of scan, an aperture ratio of 1:50 in the plane perpendicular to the direction of scan and a half deflecting angle of 30°, wherein the first converging means comprises first and second lenses which are sequentially arranged in the foregoing order in a direction extending away from the light source, and the second converging means comprises third, fourth and fifth lenses which are sequentially arranged in the foregoing order in a direction extending away from the deflecting surface, and wherein the following conditions are substantially satisfied: ______________________________________ f.sub.p = 287.66 f.sub.p /f.sub.v = 4.35 L/f.sub.p = 0.30 f.sub.p /r.sub.10 = 0 r.sub.1 = ∞ r.sub.1 ' = 21.004 d.sub.1 = 4.00 n.sub.1 = 1.76530 r.sub.2 = ∞ r.sub.2 ' = 17.845 first converging means d.sub.2 = 5.00 r.sub.3 = ∞ r.sub.3 ' = 45.422 d.sub.3 = 3.72 n.sub.2 = 1.76530 r.sub.4 = ∞ r.sub.4 ' = ∞ d.sub.4 = 70.73 r.sub.5 = ∞ r.sub.5 ' = ∞ deflecting surface d.sub.5 = 20.48 r.sub.6 = -68.363 r.sub.6 ' = -68.363 d.sub.6 = 16.61 n.sub.3 = 1.78506 r.sub.7 = -77.695 r.sub.7 ' = -77.695 d.sub.7 = 0.00 r.sub.8 = 11425.394 r.sub.8 ' = 11425.394 second converging d.sub.8 = 17.01 n.sub.4 = 1.78506 means r.sub.9 = -8531.994 r.sub.9 ' = -8531.994 d.sub.9 = 35.96 r.sub.10 = ∞ r.sub.10 ' = -89.050 d.sub.10 = 16.53 n.sub.5 = 1.67450 r.sub.11 = -208.951 r.sub.11 ' = -34.131 ______________________________________ where f p denotes a focal length of the second converging means with respect to refraction in the plane parallel to the direction of scan; f v , a focal length of the second converging means with respect to refraction in the plane perpendicular to the direction of scan; L, a length of the second converging means; r 1 through r 11 , respective radii of curvature with respect to refraction in the plane parallel to the direction of scan of the surfaces of the lenses comprising the converging means as taken in sequence in the direction extending away from the light source and then in the direction extending away from the deflecting surface; r 1 ' through r 11 ', respective radii of curvature with respect to refraction in the plane perpendicular to the direction of scan of each of the surfaces as taken in said sequence; and d 1 through d 10 , a distance between each adjacent two of the surfaces as taken in said sequence; and n 1 through n 5 , an index of refraction at a wavelength of 790 nm of each of the lenses in said sequence.