Dark Current & Temperature
Simulate thermally generated dark current in CMOS pixels and visualize its impact on image quality across operating temperatures.
Dark Current & Noise Simulator
Simulate temperature-dependent dark current, noise budget, and dark frame pattern for CMOS image sensor pixels.
Dark Current vs Temperature
Noise Budget vs Temperature
Dark Frame Visualization
Simulated dark frame image showing noise pattern at current temperature and integration time.
Physics
Dark current is the signal generated by thermal carrier generation in the absence of light. It follows the Arrhenius model:
J_d(T) proportional to exp(-E_g / 2kT)
where E_g is the silicon bandgap (~1.12 eV), k is Boltzmann's constant, and T is absolute temperature.
Temperature Doubling Rule
A widely used approximation: dark current approximately doubles for every 6-8 degrees C increase in temperature. This makes thermal management critical for long-exposure and scientific imaging applications.
Impact on Image Quality
- Noise floor — dark current shot noise (sqrt of dark signal) adds to the total noise, degrading SNR in low-light conditions
- Fixed pattern noise — pixel-to-pixel variation in dark current creates a static pattern that must be subtracted via dark frame calibration
- Hot pixels — defect sites with anomalously high dark current appear as bright dots, becoming more prevalent at elevated temperatures
Dark Frame Simulation
The simulator generates a synthetic dark frame showing statistical variation across pixels, including the long tail of hot pixels characteristic of real sensors.
TIP
For scientific cameras, cooling the sensor by 20 degrees C can reduce dark current by roughly 8x, dramatically improving performance for long exposures.