Abstract: An optical touch device includes: two light beam scanning modules each scanning a touch region of a panel body with a scanning light beam, whose incident angle varies with time, and outputting a time index signal associated with the incident angle; two light sensor modules each sensing a corresponding reflected scanning light beam generated due to presence of a touch within the touch region so as to output a sensing signal; and a processing unit for locating the touch based on the time index signal from each light beam scanning module, the sensing signal from each light sensor module, and a look-up table having pieces of angle information corresponding to a series of time indexes and associated with the incident angle of each scanning light beam.