Abstract: A wide angle optical lens assembly includes a first lens group and a second lens group arranged in order from an object side to an image plane along an optical axis, satisfying the following condition: 2.0?|F1/EFL|?3.65; 2.6?|F2/EFL|?3.45; wherein, EFL is effective focal length of the wide angle optical lens assembly; F1 is effective focal length of the first lens group; F2 is effective focal length of the second lens group. The first lens group includes a first lens having negative refractive power, a second lens having negative refractive power, and a third lens having positive refractive power arranged in order from the object side. The second lens is a meniscus lens, having a convex image-side surface. The second lens group includes a fourth lens having positive refractive power, a fifth lens having negative refractive power, and a sixth lens having positive refractive power arranged in order from the object side.

Abstract: A wide angle lens assembly having low distortion including, in order from an object side to an image plane, a first lens, which is of a meniscus shape having an object side surface being convex and an image side surface being concave, having negative refractive power; a second lens having positive refractive power; a third lens having positive refractive power, and a fourth lens having negative refractive power; the wide angle lens assembly satisfies the following condition: ?0.6<f34/f12<?0.4; wherein f12 is a composite focal length of the first lens and the second lens, and f34 is a composite focal length of the third lens and the fourth lens.

Abstract: A wide angle lens assembly having low distortion including, in order from an object side to an image plane, a first lens, which is of a meniscus shape having an object side surface being convex and an image side surface being concave, having negative refractive power; a second lens having positive refractive power; a third lens having positive refractive power, and a fourth lens having negative refractive power; the wide angle lens assembly satisfies the following condition: ?0.6<f34/f12<?0.4; wherein f12 is a composite focal length of the first lens and the second lens, and f34 is a composite focal length of the third lens and the fourth lens.

Abstract: A projecting device with a cylindrical color tube for displaying color images. The projecting device includes a light source for generating a trichrome light beam, a cylindrical color tube for filtering the trichrome light beam into red, green and blue light beams, a driving device for rotating the color tube, an optical modulator for converting an image signal into an image and modulating the image into the red, green and blue light beams outputted from the color tube to generate a modulated light beam, and a projecting lens installed in the housing for projecting the modulated light beam onto a screen.

Abstract: A projection device has a light source, a polarization converter, a cross dichroic mirror set that has two dichroic mirrors, a modulation device and a projection lens. The light source provides white unpolarized light. The polarization converter converts the white unpolarized light into white polarized light. The two dichroic mirrors have a cross-like arrangement and are used to separate the white polarized light into three monochromatic polarized beams. The modulation device is positioned adjacent to the cross dichroic mirror set. The modulation device modulates the three monochromatic polarized beams to form three monochromatic polarized modulated beams, and reflects the three monochromatic polarized modulated beams to the two dichroic mirrors. The two dichroic mirrors recombine the three monochromatic polarized modulated beams to form a white polarized modulated beam. Finally, the projection lens projects the white polarized modulated beam to form an image.

Abstract: Both of the first surface and the second surface of the one-piece f.THETA.-DEC scanning lens of the present invention have to be in accordance with the following equation: ##EQU1## and the following criterion has to be satisfied: (1) 0.27.ltoreq.fx/fy.ltoreq.0.35(2) .vertline. R.sub.1 y .vertline. > .vertline. R.sub.2 y .vertline.(3) 0.3<R.sub.2 x/R.sub.2 y<0.6, R.sub.1 x/R.sub.1 y.ltoreq.0Therefore, the one-piece f.THETA.-DEC scanning lens of the present invention is capable of replacing a convention two-element f.THETA. lens group so as to compensate the Wobble effect, scan linearly, and greatly decrease the setup volume of the scanner at the same time.