Optical: systems and elements – Collimating of light beam
Reexamination Certificate
2000-09-13
2001-11-27
Epps, Georgia (Department: 2873)
Optical: systems and elements
Collimating of light beam
C359S793000
Reexamination Certificate
active
06324013
ABSTRACT:
BACKGROUND OF THE INVENTION
Various optical scanning devices used in laser beam scanning such as in copy machines, laser printers, and the like, or for recording or displaying picture images are conventionally known. Such optical scanning devices generally use a collimator lens to collimate the light beam received from, for example, a semiconductor laser, and are constructed so as to scan an image using a rotating multi-faceted mirror and an f·&thgr; lens. Collimator lenses consisting of two lens elements are disclosed in Japanese Laid Open Patent Applications S58-14109, S58-38915, S61-279820, S61-273520, and H2-73324. These collimator lenses are light in weight and compact.
When using a collimator lens in conjunction with an optical scanning device, the numerical aperture of the collimator lens that is employed is generally larger than that of the f 0 lens, in order to obtain high efficiency in gathering the light from a light source. However, such a design produces greater aberrations. Therefore, the aberrations of the collimator lens generally need to be corrected carefully.
Furthermore, in an optical scanning device, a multiple beam format is used for multi-beam scanning that uses multiple light sources, making it possible to either increase the scan speed or to make simultaneous recordings in one scan. In cases where a multi-beam format is used, favorable aberration correction is desirable within a half-picture angle so of two degrees.
With the above-mentioned collimator lenses, little consideration has apparently been given to the performance of the collimator lens at large picture angles. If the picture angle is large, since the various aberrations become troublesome, it becomes difficult to successfully use these lenses in a multibeam scanning optical system in which multiple light sources are arranged on a plane surface that is normal to the optical axis. In addition, in the case where use is made of a semiconductor laser as the light source, the phenomenon of mode hopping occurs as a result of changes in the ambient temperature or changes in the drive current. When mode hopping occurs, the output wavelength of the laser shifts, and this results in the position of the focus on the image-forming surface shifting due to the system magnification being dependent on the wavelength of the light. Thus, mode hopping makes it more difficult to record information with a high degree of resolution in that the various aberrations need to be well-corrected relative to the oscillation wavelength of the laser. However, the prior art collimator lenses referred to above do not adequately correct for aberrations due to a change in oscillation wavelength of the light source.
BRIEF SUMMARY OF THE INVENTION
The present invention relates to a collimator lens used in scanning devices, such as copy machines, laser printers and the like, for scanning laser beams, and recording or displaying an image. In particular, it relates to a collimator lens, and the optical scanning device which uses it, for converting optical flux emitted by a semiconductor laser into a collimated beam. A first object of the present invention is to provide a collimator lens that can be used to scan multiple light sources wherein off-axis aberrations are favorably corrected for a half-picture angle of 2 degrees. A second object of the invention is to provide a collimator lens which favorably corrects for aberrations due to a change in oscillation wavelength of the light source.
REFERENCES:
patent: 5270851 (1993-12-01), Makino
patent: 5691847 (1997-11-01), Chen
patent: 5838480 (1998-11-01), McIntyre
patent: 5838497 (1998-11-01), Maruyama
patent: 5978132 (1999-11-01), Ulrich
patent: 6005703 (1999-12-01), Maddox
patent: 6038053 (2000-03-01), Kato
patent: 6061183 (2000-05-01), Nakai
patent: 6067196 (2000-05-01), Yamamoto et al.
patent: 6101020 (2000-08-01), Ori
patent: 6115164 (2000-09-01), Kamikubo
patent: 6115192 (2000-09-01), McDonald
patent: 6236512 (2001-05-01), Nakai
patent: 58-14109 (1983-01-01), None
patent: 58-38915 (1983-03-01), None
patent: 61-279820 (1986-12-01), None
patent: 61-273520 (1986-12-01), None
patent: 2-733324 (1990-03-01), None
Arnold Bruce Y.
Arnold International
Epps Georgia
Fuji Photo Optical Co., Ltd.
O'Neill Gary
LandOfFree
Collimator lens and optical scanning device which uses it does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Collimator lens and optical scanning device which uses it, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Collimator lens and optical scanning device which uses it will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2582488