Optical: systems and elements – Diffraction – From zone plate
Reexamination Certificate
1997-05-13
2004-08-17
Spyrou, Cassandra (Department: 2872)
Optical: systems and elements
Diffraction
From zone plate
C359S569000, C359S722000, C359S742000, C359S350000, C353S055000, C353S102000
Reexamination Certificate
active
06778326
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to devices utilizing heat filters and condenser lenses and, in particular, to projection aparatii and similar devices.
2. Description of the Prior Art
It is a common experience of 35 mm projection slide viewing to have watched a valuable yet fragile slide crinkle up in the projection gate because a broken heat filter was not replaced before the projector was used again. This experience is not limited to 35 mm slide projectors but occurs in other projection type devices utilizing a separate heat filter.
U.S. Pat. No. 4,850,685 (col. 3, lns. 65-68) refers to a separate condenser lens and a heat filter that are combined in light source member module (i.e. housing). This approach does not solve the broken heat filter problem.
U.S. Pat. No. 3,953,730 also refers to a condenser which contains a heat filter 190. However, the condenser lens elements are separated from the heat filter even though they are located in the same “condenser module.”
SUMMARY OF THE INVENTION
It is an object of the present invention to provide efficient means for projection viewing, and in particular projection slide viewing, that would prevent a heat-related breakup of a heat filter in projection type devices.
It is also an object of the present invention to provide a single optical component capable of serving both as a condenser lens element and as a heat absorption filter.
These and other objects are achieved by a heat absorptive optical component having a front surface and a rear surface where one of the surfaces is a crenulate surface having optical power.
According to one embodiment of the present invention, the crenulate surface is a diffractive surface.
According to another embodiment, it is a Fresnel surface.
It is also an object of the present invention to provide a projector apparatus comprising an integral condenser lens element and heat filter.
The crenulate surface serves two purposes. First, it permits design of a condenser lens with a uniform or near uniform thickness and therefore, uniform heat absorption. Second, it provides much more surface area than a plano or spherical surface to re-radiate or otherwise dissipate the heat. This latter feature greatly reduces the tendency of the element to break.
An additional advantage of the invention is the reduction in the number of optical components required in an assembly of the projector-type devices with a corresponding reduction in parts costs as well as assembly costs and the increased quality of such devices (no prize slides fried before an audience).
REFERENCES:
patent: 3632198 (1972-01-01), Puffer
patent: 3953730 (1976-04-01), Henry et al.
patent: 3982822 (1976-09-01), Conder et al.
patent: 4118761 (1978-10-01), Dey
patent: 4583815 (1986-04-01), Taga et al.
patent: 4643524 (1987-02-01), Mori
patent: 4850685 (1989-07-01), Kamakura et al.
patent: 4900129 (1990-02-01), Vanderwerf
patent: 5022740 (1991-06-01), Maziork
patent: 5036025 (1991-07-01), Lin
patent: 5046838 (1991-09-01), Iwasaki
patent: 5218471 (1993-06-01), Swanson et al.
patent: 5234871 (1993-08-01), Krashkevich
patent: 5262880 (1993-11-01), Abileah
patent: 5353211 (1994-10-01), Merko
patent: 58-43401 (1983-03-01), None
patent: 59-180501 (1984-10-01), None
patent: 03-23415 (1991-01-01), None
patent: 04-9803 (1992-01-01), None
G. J. Swanson, “Binary Optics Technology: The Theory and Design of Multi-Level Diffractive Optical Elements”, Mass. Inst. Tech., Lincoln Laboratory, Technical Report 854, Aug. 1989.
Eastman Kodak Company
Jr. John Juba
Short Svetlana Z.
Spyrou Cassandra
LandOfFree
Combined heat filter and condenser lens, a projection type... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Combined heat filter and condenser lens, a projection type..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Combined heat filter and condenser lens, a projection type... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3270485