Radiant energy – Invisible radiant energy responsive electric signalling – Infrared responsive
Reexamination Certificate
2000-12-29
2003-09-30
Hannaher, Constantine (Department: 2878)
Radiant energy
Invisible radiant energy responsive electric signalling
Infrared responsive
C257S437000, C257S680000
Reexamination Certificate
active
06627892
ABSTRACT:
TECHNICAL FIELD
The present invention concerns thermal imaging, and more specifically concerns structures and methods for packaging arrays of infrared detectors.
BACKGROUND
Night vision and related applications can be realized by receiving the infrared radiation emitted by warm bodies in an array of uncooled bolometer pixels or other detector whose electrical output signals are converted into a visible image.
An array of uncooled bolometers or similar detector on a semiconductor substrate must be packaged so as to protect the detector pixels from contamination and degradation. Many conventional integrated-circuit packaging techniques are not suitable because the face of the array must be exposed to incident radiation.
A package cover can be fabricated from a material that transmits infrared, such as silicon, to provide a window for a detector array. A cavity can be micromachined into the cover so that the cover can be sealed to a substrate holding the array. Evacuating the sealed cavity produces a vacuum that protects the array pixels and their circuitry on the substrate.
The high indices of refraction of infrared optical components causes large insertion losses. Many conventional infrared-detector packages employ antireflection layers or coatings for reducing insertion losses to a more acceptable level. However, when the optical element is a window formed in a cavity, applying an effective antireflective element within the cavity is difficult. In addition to the performance degradation from the high temperatures required for many such coatings, it is difficult to achieve uniformity in a depressed surface such as a cavity.
SUMMARY
An infrared detector according to the invention has a window in a cover having a cavity for exposing one or more detector pixels to incident radiation. The window has an antireflective element formed within the cavity as a field of posts having a height, spacing, and fill factor for achieving the desired optical effect in a wavelength range of interest.
In another aspect, the invention concerns fabricating an infrared optical element. A field of post structures is formed in a cavity by etching the posts in a desired pattern and forming the cavity by a general etch over the area of the field.
REFERENCES:
patent: 4536608 (1985-08-01), Sheng et al.
patent: 4554727 (1985-11-01), Deckman et al.
patent: 4760440 (1988-07-01), Bigler et al.
patent: 4826267 (1989-05-01), Hall et al.
patent: 5151917 (1992-09-01), Perilloux et al.
patent: 5417799 (1995-05-01), Daley et al.
patent: 5895233 (1999-04-01), Higashi et al.
patent: 6359735 (2002-03-01), Gombert et al.
patent: 6384473 (2002-05-01), Peterson et al.
patent: WO-95/17014 (1995-06-01), None
Motamedi, M.E., et al., “Antireflection surfaces in silicon using binary optics technology”,Applied Optics, 31(22), pp. 4371-4376, (Aug. 1992).
KWA, T..A, et al., “Intergrated Grating/Detector Array Fabricated in Silicon Using Micromachining Techniques”,Sensors and Actuators A, 31, (1992),256-266.
Gagliardi Albert
Hannaher Constantine
Honeywell International , Inc.
LandOfFree
Infrared detector packaged with improved antireflection element does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Infrared detector packaged with improved antireflection element, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Infrared detector packaged with improved antireflection element will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3055379