An optical method and apparatus are described for the measurement of
properties of a travel vehicle or a travel surface upon which the travel
vehicle travels, which includes providing an incident light from a light
source to the travel surface, collecting light reflected from the travel
surface, determining a surface induced Doppler shift from the incident
and collected light and determining at least one of a motion property of
the travel vehicle and a surface property of the travel surface based on
the determined surface induced Doppler shift.