Vaisala CT25K - 1.2.6 Transmitter; 1.2.7 Receiver

Ceilometer CT25K
User’s Guide CT25K-U059en-2.1
8
1.2.6 Transmitter
Laser Source: Indium Gallium Arsenide (InGaAs) Diode
Laser
Center Wavelength: 905 ± 5 nm at 25 °C (77 °F)
Operating Mode: Pulsed
Nominal Pulse Properties at Full Range Measurement:
Energy: 1.6 µWs ± 20% (factory adjustment)
Peak Power: 16 W typical
Width, 50%: 100 ns typical
Repetition Rate: 5.57 kHz
Average Power: 8.9 mW (full range measurement)
Max Irradiance: 170 µW/cm² measured with 7 mm aperture
Laser Classification: Officially certified as Class 1 laser device in
accordance with EN 60 825-1:1994
Class 1 in compliance with FDA CFR
1040.10 (Subsection e,3)
Laser Source Geometry: Five-stack, 0.4 mm (16 mil) square
Beam Divergence: ± 0.53 mrad edge, ± 0.75 mrad diagonal
1.2.7 Receiver
Detector: Silicon Avalanche Photodiode (APD)
Responsivity at 905 nm: 65 A/W
(factory adjustment)
Surface Diameter: 0.5 mm (0.02 in.)
Interference Filter: Center wavelength 908 nm typical
50% Pass Band: 35 nm at 890-925 nm typical
Transmissivity at 905 nm: 80 % typical, 70 % minimum
Field-of-View Divergence: ± 0.66 mrad