Real time control of the spatial selectivity during laser treatment of a biological surface

We propose a new irradiation technique to improve the spatial selectivity and the dose control during a laser treatment of a biological surface. The technique is based on the use of a spatial light modulator to project a rectangular laser image of 8 mm x 5 mm. The spatial distribution of the irradiation is controlled in real time by image analysis applied to the acquired image of the surface to be treated. The aim is to discriminate between the target areas to be irradiated and the surrounding parts to be preserved. The resolution is about 12 microm and is limited by the resolution of the camera and the spatial light modulator. For treatments of a large surface we use an intensity correlator to measure the displacement and to avoid an unwanted second irradiation on a target.