Wide Dynamic Range Imaging Sensor And Method

Abstract

A system and method for sensing an optical input having a wide dynamic range includes providing a semiconductor material extending along a reference axis away from an optical input surface and having more than one substantially planar photodetecting regions disposed therein at different respective depths. The substantially planar photodetecting regions are configured to be overlapping and at least partially transverse to the reference axis, such that more than one of the regions absorb the optical input received through the optical input surface. Each of the photodetecting regions has an associated responsivity representative of the absorption of the incident optical signal. Preferably, the responsivity of each of the photodetecting regions is different for each of the photodetecting regions. A wide dynamic range sensor signal is produced by combining electrical output signals obtained from each of the more than one photodetecting regions.

What is claimed is: 
     
         1 . A method for generating a wide dynamic range image, comprising the steps of:
 providing a semiconductor block extending from an input face along a reference axis, wherein points in the semiconductor block are characterized by hole-electron pair photocharge generation coefficient as a function of wavelength of incident illumination across a predetermined wavelength range;   directing an optical signal to be incident on the input face, to generate a photo-generated spatial charge distribution in the semiconductor block;   detecting the photo-generated spatial charge distribution resident in a plurality of substantially planar regions of the semiconductor block, wherein the plurality of substantially planar regions are (i) non-intersecting, (ii) at least partially transverse to the reference axis, (iii) mutually spaced apart along the reference axis, and (iv) overlapping in the direction of the reference axis; and   generating an image signal representative of a weighted sum of the detected spatial charge distributions for the plurality of substantially planar regions of the semiconductor block, wherein each of the weights of the weighted sum is proportional to the integral of the photocharge generation coefficient over the predetermined wavelength range for the respective substantially planar region.   
     
     
         2 . The method of  claim 1 , wherein the semiconductor block includes a plurality of stacked signal integration wells at a single pixel location. 
     
     
         3 . The method of  claim 2 , wherein the stacked signal integration wells are positioned vertical to one another. 
     
     
         4 . The method of  claim 2 , wherein the stacked signal integration wells are configured to perform contrast blending at each pixel location. 
     
     
         5 . The method of  claim 2 , wherein the stacked signal integration wells are characterized by a monotonically increasing attenuation factor as a function of depth of each of the integration wells. 
     
     
         6 . The method of  claim 1 , wherein the detecting of the photo-generated spatial charge distribution in the semiconductor block is a function of the wavelength. 
     
     
         7 . The method of  claim 1 , wherein the optical signal comprises light. 
     
     
         8 . A method for capturing a wide dynamic range image using a semiconductor material, the semiconductor material including a plurality of substantially planar regions positioned along a principal axis, the steps of the method comprising:
 exposing the semiconductor material to an optical signal, the optical signal being directed in a path substantially incident on a face of the semiconductor material, wherein the semiconductor material is configured such that the plurality of substantially planar regions absorb the incident optical signal;   detecting a spatial charge distribution present in the plurality of substantially planar regions of the semiconductor material, wherein the planar regions are configured to be at least partially transverse to the principal axis, the spatial charge distribution of each of the substantially planar regions having a photo-generation coefficient representative of the absorption of the incident optical signal; and   generating an imaging signal representative of an aggregated sum of the spatial charge distributions in each of the plurality of substantially planar regions of the semiconductor material, wherein the integral of the photo-generation coefficient of each of the substantially planar regions over a predetermined wavelength of the incident optical signal is different for each of the substantially planar regions of the semiconductor material.   
     
     
         9 . The method of  claim 1 , wherein the plurality of substantially planar regions of the semiconductor material are mutually spaced apart along a principal axis. 
     
     
         10 . The method of  claim 1 , wherein the plurality of substantially planar regions of the semiconductor material are non-intersecting. 
     
     
         11 . The method of  claim 1 , wherein the semiconductor material includes a plurality of stacked signal integration wells at a single pixel location. 
     
     
         12 . The method of  claim 11 , wherein the stacked signal integration wells are positioned vertical to one another. 
     
     
         13 . The method of  claim 11 , wherein the stacked signal integration wells are configured to perform contrast blending at each pixel location. 
     
     
         14 . The method of  claim 11 , wherein the stacked signal integration wells are characterized by a monotonically increasing attenuation factor as a function of depth of each of the integration wells. 
     
     
         15 . The method of  claim 8 , wherein the absorption of the incident optical signal in the semiconductor material is a function of the wavelength. 
     
     
         16 . The method of  claim 8 , wherein the optical signal comprises light. 
     
     
         17 . The method of  claim 8 , wherein photo-generation coefficient is a function of the wavelength of the incident optical signal over predetermined wavelength range. 
     
     
         18 . The method of  claim 8 , wherein the step of exposing the semiconductor material is performed in a single frame. 
     
     
         19 . A high dynamic range imaging sensor element comprising:
 a semiconductor material extending away from an optical input surface along a reference axis;   a plurality of substantially planar, non-intersecting photodetecting junctions each disposed within the semiconductor material and providing a respective output signal responsive to an optical input, each of the photodetecting junctions also being (i) at least partially transverse to the reference axis, (ii) mutually spaced apart along the reference axis, and (iii) overlapping in the direction of the reference axis; and   a signal combiner in electrical communication with at least two of the plurality of photodetecting junctions, the signal combiner providing a high dynamic range output signal derived from the output signals of each of at least two photodetecting junctions, a dynamic range of the high dynamic range output signal being greater than a dynamic range any one of the at least two photodetecting junctions.   
     
     
         20 . The high dynamic range pixel element of  claim 19 , further comprising an optical filter positioned between the optical input surface and the optical input, the optical filter restricting operation of the plurality of photodetecting junctions to a preferred spectral region, wherein a mean value of a spectral response associated with each of the plurality of photodetecting junctions determined over the preferred spectral region substantially differs from a mean value of a spectral response determined over the preferred spectral region of any other of the plurality of photodetecting junctions. 
     
     
         21 . The high dynamic range pixel element of  claim 20 , wherein the mean value of the spectral response associated with each of the plurality of photodetecting junctions determined over the preferred spectral region differs from the mean value of the spectral response determined over the preferred spectral region of any other of the plurality of photodetecting junctions by at least a factor of two. 
     
     
         22 . The high dynamic range pixel element of  claim 19 , further comprising a signal conditioner positioned between at least one of the plurality of photodetecting junctions and the signal combiner for adjusting a level of an associated one of the photodetecting junctions. 
     
     
         23 . The high dynamic range pixel element of  claim 22 , wherein the signal conditioner comprises at least one of a signal attenuator and a signal amplifier. 
     
     
         24 . The high dynamic range pixel element of  claim 19 , wherein the respective output signal associated with each of the plurality of photodetecting junctions corresponds to a depth of the respective photodetecting junction, such that the respective output signal associated with each of the plurality of photodetecting junctions substantially differ from the respective output signal of any other of the plurality of photodetecting junctions. 
     
     
         25 . The high dynamic range pixel element of  claim 24 , wherein the depth of at least one of the plurality of photodetecting junctions is variable according to an applied input. 
     
     
         26 . A method for generating a wide dynamic range of operation in imaging sensor element comprising:
 providing a semiconductor material extending away from an optical input surface along a reference axis, the semiconductor material having an associated attenuation coefficient and producing hole-electron pairs in response to incident illumination, the hole-electron pairs being produced at various depths measured from the optical input surface along the reference axis;   receiving an optical input incident upon the optical input surface;   optically filtering the optical input thereby restricting operation to a preferred spectral region;   detecting a respective output signal responsive to the optical input at each of a plurality of substantially planar, non-intersecting photodetecting junctions each disposed within the semiconductor material, each of the photodetecting junctions also being (i) at least partially transverse to the reference axis, (ii) mutually spaced apart along the reference axis, and (iii) overlapping in the direction of the reference axis; and   combining output signals from least two of the plurality of photodetecting junctions, the combination yielding a wider dynamic range output signal than that provided by any one of the at least two photodetecting junctions.   
     
     
         27 . The method of  claim 26 , wherein a mean value of a spectral response associated with each of the plurality of photodetecting junctions determined over the preferred spectral region substantially differs from a mean value of a spectral response determined over the preferred spectral region of any other of the plurality of photodetecting junctions. 
     
     
         28 . The method of  claim 26 , further comprising level adjusting at least one of the output signals of the plurality of photodetecting junctions. 
     
     
         29 . The method of  claim 26 , further comprising determining a color associated with the incident illumination and combining the color with the combined output signals from least two of the plurality of photodetecting junctions, the further combination yielding a color overlaid, wide dynamic range output signal.