| 摘要 |
A method and apparatus for controlling the removal of unwanted material from a site wherein there are present other materials utilizes pulses of high intensity radiant energy such as a laser beam. The control is accomplished by illuminating the site, with visible or invisible optical radiation, and subjecting the reflected optical radiation therefrom to spatial spectral dispersion. The spatial spectral dispersion is sensed and an electronic signal representative thereof is generated. The generated electronic signal is compared to a pre-recorded electronic signal representative of the spatial spectral dispersion of optical radiation reflected from the material to be removed before each pulse of high intensity radiant energy is applied to the surface, and the pulse is applied only upon such comparison resulting in a substantial match. Rastering with dithering is preferably used to accommodate industrial laser characteristics, to reduce site heating, to reduce the requirement of perpendicularity to the surface, and to accommodate contour features of the surface. Methods and means for normalization of the sensed spatial spectral dispersion and for utilizing mismatch comparisons are disclosed. The system is disclosed particularly in the context of surgical procedures for removal of tumors, bodies of matter causing blood vessel blockage, and other surgical procedures wherein selectivity between unwanted or deleterious material and normal tissue is critical.
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