Single Photon Detector HDR Imaging via Dead-Time Correction
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Solution Overview
Problem
Conventional image sensors face limitations in capturing high dynamic range scenes due to saturation in bright regions and noise in dark regions, with existing HDR techniques suffering from artifacts and manufacturing challenges in achieving small pixel sizes for improved dynamic range.
Innovation Solution
A system utilizing dead-time-limited single photon detectors, where each pixel includes a single photon avalanche diode with a counter and processor to calculate intensity values based on photon detection times, enabling high dynamic range imaging without hardware modifications for non-linear response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional image sensors are used to capture scenes with high dynamic range, then the sensor can capture images, but bright regions saturate and dark regions are dominated by noise
Solution Approach 1:
The patent changes the fundamental detection parameter from measuring continuous light intensity (conventional sensors) to counting discrete photon arrival events (single-photon detectors). This parameter change enables the system to accurately measure both very bright and very dark regions without saturation or noise dominance, achieving high dynamic range with maintained signal quality.
2Illumination intensity
If exposure bracketing with multiple images is used to increase dynamic range, then dynamic range is improved, but ghosting artifacts appear in dynamic scenes
Solution Approach 1:
The patent performs preliminary action by having the single-photon detector continuously count photon arrivals throughout the entire exposure time, recording the temporal distribution of photon events. This preliminary counting action enables the system to capture the complete dynamic range in a single shot without requiring multiple exposures, thereby avoiding ghosting artifacts while preserving image quality.
3Loss of information
If single-shot HDR sensors with optical elements are used to avoid ghosting, then ghosting artifacts are reduced, but device complexity increases
Solution Approach 1:
The patent extracts the complex optical elements (neutral density filters, beam-splitters) from the sensor structure and replaces them with a simplified single-photon detector that achieves HDR through photon counting statistics. This extraction of unnecessary optical components significantly reduces device complexity while maintaining the ability to capture high dynamic range scenes in a single shot without ghosting artifacts.
4Illumination intensity
If quanta image sensors with sub-diffraction-limit pixels are used to improve dynamic range, then dynamic range increases, but manufacturing precision requirements become extremely high
Solution Approach 1:
The patent changes the detection mechanism from spatial oversampling with sub-diffraction-limit pixels (QIS) to temporal photon counting with standard-sized pixels. This parameter change from spatial to temporal domain enables high dynamic range with conventional pixel sizes, eliminating the extreme manufacturing precision requirements while maintaining improved dynamic range performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly enhances the dynamic range of images by overcoming saturation limits and noise issues, providing a high dynamic range imaging solution that outperforms conventional sensors with improved signal-to-noise ratio and reduced manufacturing complexities.
Implementation Method 1
a single photon detector configured to detect the arrival of a single photon
Implementation Method 2
having a dead time τd after detection of a photon
Data Source
AI summary
In accordance with some embodiments, systems, methods and media for high dynamic range imaging using dead-time-limited single photon detectors are provided. In some embodiments, a system for high dynamic range imaging is provided, comprising: an image sensor comprising: a pixels comprising: a single photon detector having dead time τd; and a counter coupled to an output of the single photon detector, wherein the counter is configured to increment in response to a signal indicative of detection of a photon output by the single photon detector; and a processor that is programmed to: read out a value stored by the counter after an exposure time has elapsed; and calculate an intensity for the pixel based on the value and the dead time τd.