Color corrected f-theta lens for ultrashort pulse lasers

05. February 2019

We present the first of its kind fully color corrected f-theta scan lens for ultra-short pulse lasers from Sill Optics GmbH & Co. KG.

Lasers with pulses shorter than 1 picosecond create a noticeable spectral bandwidth which will degrade the spot performance via chromatic errors.
For example, an 800 femtosecond Gaussian shaped pulse has a spectral width of about 2 nm and a 250 femtosecond pulse has a width of almost 7 nm (1064 nm, FWHM). This will aberrate the spot in an f-theta lens which is designed to focus only one wavelength.

Two new scan lenses from Sill Optics use multiple glass types in its design so all the wavelengths within a pulse are in focus at the work surface. The lenses have focal lengths of 100 mm, are telecentric, have scan areas of 35 mm x 35 mm and will accept a maximum 10 mm 1/e² input beam.
The S4LFT7010/008 covers from 1500 – 160 nm, the S4LFT7010/450 from 1000 – 1100 nm and the S4LFT7012/292 from 510 – 590 nm. All three lenses are designed to have no internal ghosts or back reflections which can damage lens elements within the lens.

Our product range also includes an ultrashort pulse compatible beam expander with fixed magnification factor of three and designed
for 1000 – 1100 nm range. The S6ASS4803/450 has a 10 mm (1/e²) maximum input beam diameter and  M30 x 1 mounting.