Telecentric scan lenses with 48 mm focal length

04. January 2021

In general the rule in optics is that a large image sided NA means a small minimum spot size. So steeply focused, diffraction limited beams result in a very fine spot. Thus scan lenses with short focal lengths and large input beam diameters can achieve a smaller focus diameter than lenses with long focal lengths and small input beams.

This can also be seen in the formula for calculating the minimum spot size:

 

dF =  λ·APO·f'·M² / dL

dF: focal spot diameter   /   λ: wavelength   /   APO: apodisation factor   /   f': focal length   /   M²: M² value of the laser   /          dL: entrance bem diameter

 

We have extended our existing series of telecentric scan lenses with a focal length of 48 mm to meet the ever increasing laser pulse power micro processing. The lenses can withstand even highest fluences because of the lens material (fused silica) and the special low‑absorption coatings. Especially for USP lasers a lens design without critical back reflections is very important.

The lenses are optimized for scanners with 7 mm to 15 mm apertures and can be easily installed using an adaptor ring. Smallest spot diameters of 6 µm at 1064 nm wavelengths, 3 µm at 532 nm and 2 µm at 355 nm can thus be achieved.

 

part numberwavelength [nm]focal length [mm]scan area [mm x mm]max. input beam-Ø [mm]working distance [mm]
S4LFT4147/3281030 - 109048.17 x 715.061.1
S4LFT4148/292515 - 54548.06 x 615.060.0
S4LFT4149/07535548.16 x 615.069.3