Laser beam formation for intracavity processing of objects

A study was made of the formation of a processing beam in a laser projection microscope with a feedback mirror. It was established that in a resonator formed by a plane feedback mirror and an investigated object, a laser beam is created producing an intensity distribution in the form of concentric circular zones in the plane of the object. Its temporal and energy characteristics were studied. It was found that one or more of the central zones can serve as the processing region, depending on the intensity distribution. It was shown experimentally that the dimensions of the processing zone could be varied continuously. A processing zone size of ~1μ, corresponding to the diffraction-limited resolution of the optical system used, was achieved.