Table 10 Étendue calculation for detectable spot sizes at 15° incidence, 0° collection, with a 50 mm collection lens.
No servo control (± 50 mm) | With servo control (± 10 mm) | |||
|---|---|---|---|---|
Detectable spot at target surface | Image on detector | Detectable spot at target surface | Image on detector | |
Lateral size of detectable spot, b | ± 13 mm | ± 2.7 mm | ||
Distance from lens | 200 mm | Equal to focal length | 200 mm | Equal to focal length |
Angular aperture, θ (half angle) | 7.1° | 27° | 7.1° | 27° |
Étendue = b sinθ | 1.6 mm | ≥ 1.6 mm | 0.33 mm | ≥ 0.33 mm |
Required detector size = \(\frac{{\acute{e} }\text{tendue}}{{\text{sin}}\theta }\) | ± 3.5 mm | ± 0.73 mm | ||
