Reducing Dark Current in SWIR Imaging with Q-Switched Lasers
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Summary
Problems
Existing SWIR imaging systems face challenges with high dark current in photodiodes, which affects the quality of detection signals and are often expensive to manufacture, limiting their integration into electronics and manufacturing capacity.
Innovation solutions
An active SWIR imaging system using Germanium photodiodes with a pulsed illumination source and a passively Q-switched laser, along with a controller to manage integration time and reduce dark current noise, and a method to compensate for dark current effects using voltage-controlled current circuits.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If Germanium photodetectors are used for SWIR imaging, then detection capability in SWIR band is improved, but dark current increases significantly
Why choose this principle:
The patent employs pulsed illumination from a passively Q-switched laser to illuminate the target intermittently rather than continuously. This periodic action synchronizes with the integration time of the photodetector array, allowing signal accumulation only during active illumination periods while minimizing dark current accumulation during off periods.
Principle concept:
If Germanium photodetectors are used for SWIR imaging, then detection capability in SWIR band is improved, but dark current increases significantly
Why choose this principle:
The system dynamically adjusts the integration time of the photodetector array to match the pulse repetition frequency of the laser illumination. By making the integration window variable and synchronized with the illumination pulses, the system optimizes signal-to-noise ratio while controlling dark current effects.
Application Domain
Data Source
AI summary:
An active SWIR imaging system using Germanium photodiodes with a pulsed illumination source and a passively Q-switched laser, along with a controller to manage integration time and reduce dark current noise, and a method to compensate for dark current effects using voltage-controlled current circuits.
Abstract
Systems and methods for imaging in the short wave infrared (SWIR), photodetectors with low dark current and associated circuits for reducing dark currents and methods for generating image information based on data of a photodetector array. A SWIR imaging system may include a pulsed illumination source operative to emit radiation pulses in the SWIR band towards a target resulting in reflected radiation from the target; (b) an imaging receiver including a plurality of Ge PDs operative to detect the reflected SWIR radiation and a controller, operative to control activation of the receiver for an integration time during which the accumulated dark current noise does not exceed the time independent readout noise.