A poor man's optical fog detector
Abstract
A detector that responds to the light that is near-forward scattered by fog droplets was developed. An unusual configuration of light source and detector was chosen to be able to detect this near-forward scattered light, without the use of highly collimated optics. The fog detector uses a low-cost commercially available source-receiver combination. The light source uses a pulsed LED (880 nm). The receiver electronics responds to pulsed signals only, so there is no influence of stray light. It is a switching device, with adjustable threshold. An algorithm to compute the Mie scattering coefficients, and a numerical integration method to calculate the contribution of various droplet sizes to the total signal reaching the receiver, were used to compute the response of the detector. Field and wind tunnel tests show that the detector can be used to control fog samplers. It can also be used to obtain statistics on fog occurrence or for traffic control.
- Publication:
-
Annals from the German Meteorological Society, No. 25: 10th International Cloud Physics Conference
- Pub Date:
- 1988
- Bibcode:
- 1988clph.conf..333M
- Keywords:
-
- Atmospheric Composition;
- Earth Atmosphere;
- Fog;
- Meteorological Instruments;
- Optical Measuring Instruments;
- Remote Sensors;
- Performance Tests;
- Systems Engineering;
- Wind Tunnel Tests;
- Instrumentation and Photography