Intensified CCD (ICCD)
Photocathode → MCP → phosphor → CCD gain chain with gating and noise analysis.
Photoelectrons
3.50
+ 3.50e-2 background in the gate
Phosphor Gain
240.0 photons/e⁻
240 at 5 kV ∝ V (effective η = 0.109 at 548 nm); decay 1.5 ms to 10 %
CCD e⁻ per Photoelectron
1.20e+4
MCP 1.00e+3 × 12.0 e⁻ per MCP electron
Output Signal per Pixel
4.20e+4 e⁻
Even field. One photoelectron puts 2.37e+3 e⁻ (mean; 19.7 %) in its centre pixel
Noise Factor F
2.5601
K_f² + 1/G_e (variance; phosphor and coupling)
ICCD SNR per Element
1.14
Photoelectrons of one pixel area, read through the spot: read noise of N_eff = 10.1 pixels, background of κ = 5.06. High-gain limit 1.14
Bare CCD SNR
0.91
Same photons at the bare QE, no gate, no background
Key Formulas
Npe = Nph·QEpc; phosphor g = η·qV/(hc/λ)
Ge = GMCP·g·ηcoupling·QECCD (CCD e⁻ per photoelectron)
F = Kf² + 1/Ge (cascade: Poisson phosphor, binomial coupling)
SNR = Npe·Ge / √(Npe·Ge²·F + κ·Nbg·Ge²·Kf² + Neff·σread²), Neff = 1/Σh², κ = Σ(h⋆h)²/(Σh²)² (1/Ge terms weighted by the spot)
Kf is a data-sheet value at working gain; the gain chart holds it fixed down to unity gain.
Model and references
Textbook approximation. A standard approximation from the literature (for example paraxial, plane-wave or Gaussian-beam), valid within the range the page states. About the tiers
Cascade: Poisson photoelectrons, tube noise factor K_f squared, Poisson phosphor (Photek gains at 5 kV, scaled ∝ V), binomial coupling. Gaussian spot read through its matched filter. No ion feedback or dark counts.
- Shockley W., Pierce J. R. (1938). A theory of noise for electron multipliers. Proc. IRE 26, 321–332. Noise factor of cascaded gain stages, F = F₁ + (F₂ − 1)/G₁ + …. doi:10.1109/JRPROC.1938.228127
- Wiza J. L. (1979). Microchannel plate detectors. Nucl. Instrum. Methods 162, 587–601. Exponential single-electron pulse heights of an unsaturated MCP (variance factor 2). doi:10.1016/0029-554X(79)90734-1
- Dussault D., Hoess P. (2004). ICCDs edge out electron-multiplying CCDs in low light. Laser Focus World 40(9). Noise factor 1.3 < F < 2.2 for ICCD and EMCCD; 1.6 for the ICCD, 1.4 (≈ √2) for the EMCCD. Full analysis: Proc. SPIE 5563, 195 (2004), doi:10.1117/12.561839. laserfocusworld.com
- Photek. Image Diode data sheet PH-DS039 Rev 02 (2021), Phosphor options: P43 240 and P46 55 photons per electron at 5 kV, peaks 548 and 530 nm. photek.com
- Stanford Computer Optics. Image intensifier: phosphor screen. P43 and P46 decay to 10 % in 1.5 ms and 0.2 µs. stanfordcomputeroptics.com
- Andor (Oxford Instruments). iStar CCD imaging specifications, DH334T: 13 µm pixels, 5 e⁻ read noise at 50 kHz, 100 000 e⁻ well; the smallest resolvable FWHM feature is about 2 CCD pixels (note 6). andor.oxinst.com
- King I. R. (1983). Accuracy of measurement of star images on a pixel array. PASP 95, 163. Noise-equivalent area 1/Σh² of a spread image. doi:10.1086/131139