Why wouldn't this be a simple case of vector components?? If theta is the angle between the runway and the wind direction, the wind component along the runway is (wind speed)*cos(theta) and the cross wind component is (wind speed)*sin(theta)...
If the level of light to be detected is extremely low, look into photomultipliers. Wavelength sensitivity is set by the materials used for the photocathode. The material will be a metal, and will thus not degrade under the influence of the UV light like plastic or semiconductor material will...
I also wonder how you will obtain the range to target, and why you want to split the beam at all. You obviously need to time the laser pulse very accurately. Some quick points, some no doubt obvious:
1) The laser must be pulsed - not a continuous beam.
2) For a range of only 100 meters, you...
