02 · Micron-Scale Focusing
The minimum achievable focal spot is fundamentally limited by diffraction and scales with wavelength. Because 213 nm is nearly five times shorter than 1064 nm, it can produce a much smaller diffraction-limited spot with comparable beam quality and focusing optics. A near-diffraction-limited 213 nm beam can therefore be focused to a spot only a few microns in diameter; obtaining an equally small spot at longer wavelengths requires much higher numerical aperture and far more demanding optics.
The smaller focal area also concentrates the pulse energy into a higher local intensity, helping drive nonlinear absorption while limiting material removal to a very small volume. This makes 213 nm picosecond lasers particularly suitable for microdrilling, high-aspect-ratio micro-holes, microcutting, microscribing, micro-patterning and precision processing of glass, fused silica, sapphire, ceramics, semiconductors and other difficult materials.