We present a spatially selective irradiation method for laser treatment of biological surfaces. The purpose is to irradiate only the pathological targets and to preserve the healthy surrounding parts. We are interested here in the optical arrangement of the device and in the evaluation of its physical limitations before it is used for medical purposes. The method uses real-time image analysis applied to the video imagery of the surface to be treated. The result of the image analysis generates the control signal to a spatial light modulator, allowing us to project an adequate repartition of laser irradiance on the surface to be treated. Experimental results demonstrate a spatial selectivity of approximately 10 microm for a 6.7 mm x 5 mm field. The optical system has no moving parts (unlike galvanometric scanners) and is able to irradiate multiple targets simultaneously with different doses.
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.
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