Glass Diffractive Optical Beam Shaper For Laser Applications

Applications, such as pico-projectors with laser sources or medical laser skin treatment, require a rectangular homogeneous beam distribution - so called flat hat distribution. However, many laser emit only Gaussian shaped light (due to the fundamental -TEM00 - mode). SCHOTT presents a glass diffractive optical element (DOE) that shapes the Gaussian light distribution into a flat hat. Optical glasses have the significant advantage of high laser durability, low scattering losses, high resistance to moisture, chemicals, and temperature compared to polymer DOEs. The element was manufactured by using SCHOTT’s precise pressing technology. DOEs made by SCHOTT are designed to use the 1st diffraction order and the continuous phase is approximated by a staircase function - typically a 16 level quantization - resulting in a theoretical diffraction efficiency of 98.7%. The design as well as the manufacturing results of SCHOTT’s DOEs are presented in comparison. The impact of laser beam quality - like divergence and wavelength - is studied by numerical simulations and by optical measurements.