ULO Optics’ ZnSe singlet scanning lenses, the TSL series, are optimised to minimise the off-axis aberrations.

  • best compromise for all aberrations, field flatness and F-theta error using a single-element, spherical surface lens
  • for beams up to 15mm full diameter
  • focal length from 75mm to over 2122 mm
  • covering field sizes from 50mm to 1500mm square
  • use extends over many engraving, marking and cutting applications
  • designed to be positioned at the same location relative to the scanning mirrors, so are directly replaceable with another focal length
  • also available mounted
  • available with a number of different coatings for different wavelengths

Standard singlet f-Theta scanning lenses for a 15 mm diameter beam:

Part NumberField SizeFocal LengthSpot diameter (s.d.)*
48TSL7550 mm75 mm171 (49) micron
48TSL10070 mm100 mm181 (41) micron
48TSL150105 mm150 mm219 (32) micron
48TSL200140 mm200 mm269 (28) micron
48TSL250175 mm250 mm320 (23) micron
48TSL300210 mm300 mm373 (20) micron
48TSL360250 mm360 mm445 (16) micron
48TSL400280 mm400 mm481 (15) micron
48TSL435300 mm435 mm525 (15) micron
48TSL720500 mm720 mm850 (9) micron
48TSL1150840 mm1150 mm1390 (6) micron
48TSL1285900 mm1285 mm1520 (7) micron
48TSL21221500 mm2122 mm2480 (3) micron

s.d.* = Standard deviation

Spot diameter is determined from optical computation and are not measured values from marking or engraving. The width of an engraved line is affected by laser power, material, scan speed, etc and is normally less than the values listed here.

Should smaller spot sizes be required for the same focusing lens, we recommend the use of multi-element lenses, or of our larger diamter singlets (Please call for more info on the larger diameter singlets).

Please note that this page is only a representation of our most commonly used replacement f-Theta singlet lenses and is not our entire product line. If there is an item not listed or you have questions, please feel free to contact us and we will be more than happy to assist you.


ULO Optics is an ISO certified company and quality is at the heart of everything we do.  With a host of industrial affiliations you can rely on ULO to deliver.