Radiant energy – Luminophor irradiation
Reexamination Certificate
1998-04-17
2001-04-03
Ham, Seungsook (Department: 2878)
Radiant energy
Luminophor irradiation
C356S417000
Reexamination Certificate
active
06211524
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to radiation detectors, and particularly to radiation detectors using radiation sensing elements whose range of detectable wavelengths has been enhanced via the presence of luminescent materials.
Description of Related Art
Conventional radiation detectors utilizing photodiodes are generally limited in the range of wavelengths that they can detect; for example conventional silicon photodiodes are not efficient in detecting ultraviolet (UV) rays, and germanium photodiodes are generally used in the infrared (IR) range. It would be highly desirable to be able to extend the range of photodiodes and other radiation sensing elements (such as charge-coupled device arrays (CCD), photomultiplier tubes (PMT) and IR detectors) to be able to detect wavelengths with greater efficiencies than their present capability.
U.S. Pat. No. 5,115,138 discloses a UV detecting device comprising an external light shielding means, a fluorescent member disposed in said external light shielding means, a light entrance means, a means to extract UV rays and guide said rays to said fluorescent member, and a photodiode. The fluorescent member upon absorption of the UV rays fluoresces, said fluorescent radiation being detected by the photodiode. It would be highly desirable to be able to eliminate the need for external shielding means and the means for extracting UV rays from the incident light. In addition the device according to U.S. Pat. No. 5,115,138 does not permit the determination of the wavelength of the radiation detected.
U.S. Pat. No. 5,196,705 discloses a luminescing dye contained in a sensing sheet which luminesces in response to incident UV light in a selected range, said luminescent light being detected by a sensor. However these materials are limiting because of the difficulty of forming luminescent dye materials into thin films, and by its self quenching properties.
SUMMARY OF THE INVENTION
An object of the present invention is to enhance the ability of radiation sensing elements, particularly photodiodes, to detect radiation of wavelengths at greater efficiencies than their present capability and eliminate the drawbacks encountered in the prior art described above. A further object is to provide a simple means to modify existing photodiodes in existing detector apparati thereby expanding their range of wavelength detection ability without having to replace the photodiodes.
This and other objects can be achieved according to the present invention by selection of a material chosen from a class of materials that luminesce upon absorption of radiation of the desired wavelength(s) to be detected. Such class of luminescent materials include polymers, oligomers, copolymers and porphyrines. These materials can be formed into thin films and are more stable in the UV range than other luminescent materials. The luminescent material is selected to be transparent to wavelengths longer than the desired wavelength(s) and will luminesce upon absorption of radiation at the desired wavelength(s). In the present invention, a layer of this material is interposed between a source of incident radiation and a radiation sensing element such as a photodiode. The incident radiation strikes the luminescent material layer. Certain wavelengths of radiation are transmitted through the luminescent material layer, and other wavelengths are absorbed by the luminescent material layer causing it to luminesce. The photodiode detects the luminescent radiation and incident radiation, registering a larger signal strength than would be measured by a photodiode without the luminescent layer present.
In a preferred embodiment, the radiation sensing element is a silicon photodiode and the luminescent material is a carbon backbone polymer. In a further preferred embodiment, the carbon backbone polymer is poly [2,7′-(9,9-dioctylfluorene)]. The polymer is deposited as a film on the photodiode by means well known in the art. Incident radiation is shone directly onto the luminescent film. The resulting luminescent radiation and incident radiation is detected by the photodiode, indicating the presence of UV rays in the incident radiation.
In another embodiment, the photodiode is a germanium photodiode. The luminescent material is selected to absorb in the visible light region and luminesce in the IR region. The luminescent material may be selected from the group consisting of polythiophene, poly(paraphenylene vinylene) and poly (paraphenylene ethynylene).
In other embodiments, the radiation sensing elements may include CCD arrays or photomultiplier tubes.
In another embodiment, the luminescent material is a silicon backbone polymer.
Other embodiments include photodiode arrays, and use of polymers in liquid form.
REFERENCES:
patent: 4015130 (1977-03-01), Landry et al.
patent: 4061922 (1977-12-01), Last
patent: 4096387 (1978-06-01), Buckley
patent: 4201916 (1980-05-01), Ellner
patent: 4241258 (1980-12-01), Cholin
patent: 4262206 (1981-04-01), Viehmann
patent: 4371897 (1983-02-01), Kramer
patent: 4403826 (1983-09-01), Presby
patent: 4452720 (1984-06-01), Harada et al.
patent: 4467208 (1984-08-01), Muller et al.
patent: 4731881 (1988-03-01), Geller
patent: 4764984 (1988-08-01), Franke et al.
patent: 4818491 (1989-04-01), Faris
patent: 4904876 (1990-02-01), Nobbs et al.
patent: 4916319 (1990-04-01), Telfair et al.
patent: 4935631 (1990-06-01), Mosley et al.
patent: 5039854 (1991-08-01), Yip et al.
patent: 5055737 (1991-10-01), Murata et al.
patent: 5058975 (1991-10-01), Sudo
patent: 5079429 (1992-01-01), Tanaka et al.
patent: 5115138 (1992-05-01), Tanaka et al.
patent: 5132530 (1992-07-01), Groh et al.
patent: 5196705 (1993-03-01), Ryan
patent: 5281820 (1994-01-01), Groh et al.
patent: 5331168 (1994-07-01), Beaubien et al.
patent: 5378896 (1995-01-01), Knjaschewitsch et al.
patent: 5557415 (1996-09-01), Nielsen et al.
patent: 5568304 (1996-10-01), Baur
patent: 5574286 (1996-11-01), Huston et al.
patent: 5585915 (1996-12-01), Kurosawa et al.
patent: 5718842 (1998-02-01), Papkovsky
Garbuzov et al, “Organic Films Deposited on Si p-n junctions: Accurate Measurements of Fluorescence Internal Efficiency, and Application to Luminescent Antireflection Coatings”, Journal of Applied Physics, dated Oct. 15, 1996, vol. 80, pp. 4644-4648.
Gustafsson et al, “Flexible Light-Emitting Diodes made from Soluble Conducting Polymers”, Nature, vol. 357, 1992, pp. 477-479.
D.D.C. Bradley,. “Conjugated Polymer Electroluminescence”, Synth. Met. 64, 1993, pp. 401-415.
Grem et.al.,. “Realization of a Blue-Light-Emitting Device using Poly(p-phenylene)”, Advanced Materials 4, 1992, pp. 36-38.
R. Wayant and M. Ediger, “Electro-Optics Handbook,” McGraw-Hill 1994, p. 15.1.
C.I. Coleman and A. Boksenberg, “Image Intensifiers”, Contemp. Phys 17, 1976, p. 209-236.
F.S. Johnson et.al., “Fluorescent Sensitized Photomultipliers for HeteroChromatic Photometry in the Ultraviolet,” J. Opt. Soc. Am. 41, 1951, pp. 702-708.
R.S. Popovic et.al., “A Silicon Ultraviolet Detector,” Sensors and Actuators A21-A23, 1990, pp. 553-558.
J.C. Larrabee et.al., “Detectivity of a UV-B Photodiode”, SPIE “Ultraviolet Technology V”, 1994, vol. 2282, pp. 297-230.
M.A. Kahn et.al., “High-responsivity Photoconductive Ultrviolet Sensors Based on Insulating GaN Epilayers,” Appl.Phys. Lett. 60, 1992, pp. 2917-2919.
M. Marchywka et.al., “Recent Results in Diamond UV Detector Research”, SPIE “Ultraviolet Technology V”, 1994, vol. 2282, pp. 20-30.
N. Kristianpoller and D. Dutton, “Optical Properties of ‘Liumogen’: A Phosphor for Wavelength Conversion,” Appl. Optics 3, 1964, pp. 287-290.
H. Nanto et.al., “Two-dimensional ultraviolet-ray sensor utilizing photostimulated luminescence in Eu-doped KCI phosphors”, SPIE “X-ray and UV Detectors”, vol. 2278, 1994, pp. 108-117.
P.F. Morrissey, et.al.,: “Vacuum-ultraviolet quantum efficiency of a phosphor-coated charge-coupled device”, Appl. Optics 33, 1994, pp. 2534-2538.
G. Naletto, et.al.,: “Fluorescence of metachrome in the far and vacuum ultraviolet spectral region”, SPIE vol. 2519, pp
Jeglinski Stefan A.
Lane Paul A.
Vardeny Zeev V.
Chang Randall W.
Daubenspeck William C.
Gottlieb Paul A.
Ham Seungsook
Hanig Richard
LandOfFree
Enhanced radiation detectors using luminescent materials does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Enhanced radiation detectors using luminescent materials, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Enhanced radiation detectors using luminescent materials will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2478674