LASER SENSING METHOD

PURPOSE:To improve the positioning accuracy of a groove by detecting the laser light spectrum intensity with a specific wavelength to reflect from the work surface to position the groove based on the difference in the spectrum intensity between a work and a groove position. CONSTITUTION:An He-Ne laser or semiconductor laser oscillator 3 to oscillate a laser beam 4 for sensing is arranged to the same axis as laser light 2 of a laser oscillator 1 for working. The laser beam 4 is allowed to scan the inside of a working head 7 via angle changing mirrors 5 and 6 and a fine beam spot 10 at that time is caught by a CCD camera 11 and the spectrum is analyzed via a filter 12, a photoelectric converter 13 and an A/D converter 14. A part where the spectrum intensity of the reflected laser light becomes minimum at the time of scanning a pipe plate 16 and a pipe 17 is detected to position the groove. Since a spectrum analysis is utilized, the positioning accuracy of the groove is improved.