Pulsed Illumination Synchronization for Global Reset Rolling Shutter Imagers
Global Reset rolling shutter imagers eliminate motion blur when pulsed light fires strictly within the dark global integration window under controlled ambient light.
Photon Flux
Radiometric Quantity
The number of light particles that strike a defined surface area within a specific time interval governs the strength of the generated electrical signal in photodetectors. Understanding this photon flux is necessary for determining the exposure requirements and optical configuration of any sensing system. This metric is expressed in units of moles or particles per second per square meter.
Sensor Saturation
High levels of incoming radiation fill the pixel storage wells faster than the sensor can read them out. If the photon flux exceeds the maximum capacity of the sensing elements, the resulting saturation wipes out contrast and makes it impossible to resolve intensity differences. This condition requires the use of neutral density filters or shortened exposure periods to bring the signal back into the linear operating region of the sensor.
Conversely, very low levels of radiation require longer integration periods to overcome the readout noise floor.
Thermal Noise
Dark current becomes the dominant noise source when the ambient light levels are extremely low. This thermal signal mimics the presence of light and limits the detection threshold of the sensor.
Measurement Standardization
Calibrating sensors for radiometry requires using a stable reference light source with a known spectral output. By comparing the sensor response to the expected photon flux from the standard, developers can establish the quantum efficiency of each pixel across different wavelengths. This verification ensures consistent results across different batches of manufacturing.