Table 1.
Comparison of typical characteristics for thermal and photochemical damage
| Property | Thermal Damage | Photochemical Damage |
|---|---|---|
| Exposure duration | µs – 10 s | > 1 s |
| Wavelength | all λ | short visible (λ < 600 nm) |
| Time course | appear in < 24 hrs | appear in 24 – 48 hrs |
| Temperature change | > 20 °C temperature ↑ | < 10 °C temperature ↑ |
| Minimal lesion size | < beam diameter | = beam diameter |
| Reciprocity of time & power | no | yes |
| Scotoma | permanent | reparable |
| Damage threshold | ∝ (irradiated area diameter)−1 ∝ time−1/4 independent of λ (for 440 nm < λ < 700 nm) |
independent of irradiated area ∝ time−1 ∝ λ |