Determination of laser beam focus position based on secondary speckles pattern analysis.

Proper positioning of a laser beam focus is a universal problem for various applications that does not have a universal solution. Quite often the taken approach relies on some sort of a calibration and temporal stability of the laser and the optical train. While such an approach can be suitable for a large number of applications its applicability becomes limited in the cases where the laser beam properties uncontrollably change with time.

Laser focus positioning method with submicrometer accuracy.

Accurate positioning of a sample is one of the primary challenges in laser micromanufacturing. There are a number of methods that allow detection of the surface position; however, only a few of them use the beam of the processing laser as a basis for the measurement. Those methods have an advantage that any changes in the processing laser beam can be inherently accommodated.

Remote atmospheric breakdown for standoff detection by using an intense short laser pulse.

A remote atmospheric breakdown is a very rich source of UV and broadband visible light that could provide an early warning of the presence of chemical-biological warfare agents at extended standoff distances. A negatively chirped laser pulse propagating in air compresses in time and focuses transversely, which results in a rapid laser intensity increase and ionization near the focal region that can be located kilometers away from the laser system. Proof-of-principle laboratory experiments are performed on the generation of remote atmospheric breakdown and the spectroscopic detection of mock biological warfare agents.