Jan Baselmans , Fellow at ASML

Jan Baselmans

Addressing complex challenges in optical systems

“I’ve done a lot of work on ILIAS – but I’ve never wanted to be seen as ‘Mr ILIAS’. Nowadays, anyone running into complex challenges with optical systems knows where to find me.”

Jan Baselmans is an optics expert. He was instrumental in the development of the ILIAS – an optical sensor, integrated in the lithography scanner, that measures lens aberrations. This sensor enables fast and accurate measurement of lens heating, which allows a control loop to correct for it.


Jan also takes part in ASML’s mentoring program, supporting the next generation of technical leaders.

Get to know Jan
  • ASML employee since 1994
  • Named a Fellow in 2012
  • Based in Veldhoven, the Netherlands


Key contributions

  • ILIAS wavefront sensor and the subsequent lens control


Optics, including light sources, illumination and projection systems



Holds 142 US patents across 100 ASML patent families