CCD量子效率计算器
使用此CCD量子效率计算器快速获得准确的计算结果。
Photoelectrons per Pixel
6.75 e-
Photoelectrons per Pixel vs Photon Flux
公式
## CCD Quantum Efficiency and Electron Count Quantum efficiency (QE) is the fraction of incoming photons that produce a detectable photoelectron in the sensor. ### Formula **N_e = F * A * QE * t** - *F* = photon flux (photons per m2 per second) - *A* = pixel area - *QE* = quantum efficiency (0 to 1) - *t* = exposure time Shot noise follows a Poisson distribution: sigma = sqrt(N_e).
计算示例
3.75 um pixels (A = 1.406e-11 m2), QE = 0.80, flux = 1e10 ph/m2/s, 60 s exposure.
- 01N_e = F * A * QE * t
- 02N_e = 1e10 * 1.406e-11 * 0.8 * 60
- 03N_e = 0.1406 * 0.8 * 60
- 04N_e = 6.749 electrons
- 05Shot noise = sqrt(6.749) = 2.60 e-
常见问题
What is a good quantum efficiency?
Modern scientific CCDs reach 90% or higher at peak wavelength. Consumer CMOS sensors typically achieve 50-80%.
Does QE vary with wavelength?
Yes, significantly. QE peaks in the visible or near-infrared and drops in the blue and UV. Spectral QE curves are important for filter selection.
What limits detection of faint objects?
Read noise at short exposures and sky background shot noise at long exposures. Higher QE helps in all regimes.