Renishaw ATOM Installation Manual page 56

Analogue speed
20 µm system - 10 m/s (−3dB)
40 µm system - 20 m/s (−3dB)
Angular speed
Angular speed depends on disc optical diameter. Use the following equation to convert to rev/min.
V × 1000 × 60
Angular speed (rev/min) =
p D
56 ATOM rotary encoder system
Where V = maximum linear speed (m/s) and D = Optical diameter (mm).