1. Field of the Invention
The present invention relates to a method and apparatus for providing enhanced resolution in photodetectors.
2. Related Art
Photodetectors are critical components in modern optical, imaging, and communications equipment, and improvements in the resolution of such devices are continually sought. The spatial resolution of a photodetector is commonly characterized by the number of pixels provided in the detector and pixel pitch. Typically, increased resolution can be achieved by increasing the number of pixels in a given photodetector, but such an approach increases manufacturing costs and increases the overall size of the detector. As such, there is a tradeoff in the optoelectronic arts between increasing device resolution while curtailing increases in manufacturing costs and detector size.
Pixel miniaturization represents one technique for increasing detector resolution while preserving detector size, but to date, such efforts have been unsatisfactory. For example, in hybrid focal plane arrays (FPAs), a number of factors can limit the ability to miniaturize pixels, including difficulty in scaling circuitry of a given topology using available process technologies, inability to efficiently and accurately deposit indium bumps and hybridize the detector array to a readout integrated circuit (including difficulties with other die-to-die interconnection schemes), difficulty in implementing closely-spaced pixels within an array, and decreased manufacturing yield as design and manufacturing limits are approached. Further, when pixels are miniaturized, imaging difficulties arise in environments with low light levels. This can be attributed to fewer photons being detected because of a decrease in the collection area at the pixel level, as well as smaller integration capacitor size attributable to smaller pixel size.
Other techniques for increasing photodetector resolution include post-sensor processing of either controlled sub-pixel motion or sub-pixel information gleaned from frame sequences in videos. As can be readily appreciated, such techniques are inefficient because they require motion of either the scene or the detector array to achieve higher resolutions, and such motion may be undesirable and/or impractical in many applications. Further, the use of post-sensor signal processing increases overall manufacturing costs, as well as the size and power dissipation of the system. Thus, each of the aforementioned techniques require modification to existing photodetector designs, and are costly to implement.
Accordingly, what would be desirable, but has not yet been provided, is a method and apparatus for providing enhanced resolution in any suitable photodetector that does not require scene or detector motion, and which can be implemented without modification to any desired photodetector array.