Fluoride Optic Laser-Damage Simulator

Optic Material

Laser Pulse Train

Pulse fluence 40 mJ/cm²

Repetition rate 200 Hz

Live Readouts

Transmission: 100.0%

Color-center density

0.00 ×10¹⁵ cm⁻³

Pulses fired

Local Δtemperature

0.0 K

Damage margin

100%

How it works

Deep-UV excimer photons (157–248 nm, 5.0–7.9 eV) carry enough energy to ionise trace lattice defects and trapped electrons in a fluoride crystal, leaving a hole trapped at an anion vacancy — an F-center. Each color center absorbs light at its own band, so their buildup steadily darkens an optic that started perfectly clear.

Per-pulse generation:  ΔN = G(λ, F) · (1 − N / N_sat)
Photon-energy scaling: G ∝ (E_photon / E_gap)^p      (p ≈ 3–4, multi-photon-like onset)
Thermal annealing:     dN/dt = −k₀ · exp(−E_a / k_B·T) · N
Beer–Lambert:          Transmission = exp(−σ · N · L)
Damage criterion:       N ≥ N_crit  →  catastrophic absorption runaway

Material — CaF₂ has a wider bandgap (~10 eV) and higher intrinsic damage threshold than MgF₂ (~11 eV bandgap but more native vacancies), so their generation rate G and critical density N_crit differ.
Wavelength — shorter wavelength = higher photon energy E_photon, pushing G(λ,F) up steeply once E_photon approaches the bandgap; this is why 157 nm F₂-laser optics damage far more easily than 248 nm KrF optics at the same fluence.
Fluence & repetition rate — higher fluence increases ΔN per pulse; a higher repetition rate leaves less time between pulses for the crystal to cool and thermally anneal existing centers back out, so heat and defects both accumulate faster.
Anneal — a real fluoride window recovers slowly by thermal annealing (or a bake-out); the button here fast-forwards that recovery so you can compare a rested vs. fatigued optic.

Real-world relevance: this exact failure mode is why 193 nm ArF lithography and 157 nm F₂ lens elements are cut from ultra-pure, low-defect CaF₂ boules rather than fused silica — ordinary optical glass would cloud over after a few million pulses.

UV pulse beam F-centers (color centers)

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