| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and an implementation apparatus thereof that can determine very accurately road surface condition, especially with respect to the existence of water, ice and/or snow, at relatively low price, independently of road coating. SOLUTION: In a determining method of road surface condition, back-scattered light from road surface is decomposed to spectrum components and a change with respect to intensity of back-scattered light obtained thus is evaluated. Therefore, back-scattered spectrum with respect to a wavelength of a dried road surface is evaluated by mathematics function with free parameters, and the function is multiplied by an exponential function absorption term describing light-transmission of a water layer with a specified thickness. Then, a change of mathematics function with respect to a wavelength of intensity of back-scattered light, which impinges on a receiver 5, is obtained. Based upon actual measurement values, free parameters of function for an approximation as correct as possible is calculated, thereby obtains especially thickness of a water layer. An implementation apparatus thereof is a spectrometer, which uses an absorption device as a substitute for a dispersion device and is directly installed on a row of CCD 8. |
