By DR. SABINA KUPRĖNAITĖ , Head of R&D, OPTOMAN With SEMI projecting 300mm fab equipment spending to rise 18% to $133 billion in 2026, more advanced tools are entering production, and their optics must do more than hit an initial reflectance target. Dr. Sabina Kuprėnaitė of OPTOMAN argues that surviving a laser pulse and staying optically stable across billions of them are different qualification questions. In one OPTOMAN test, a 193nm ion-beam-sputtered mirror was exposed to about five billion pulses at around 100 mJ/cm², with less than a 0.5% drop in normalized reflectance. She explains why laser-induced damage threshold values mean little without their test conditions, why absorption and thermal effects matter, and why replacement optics must reproduce the response the tool was qualified around, not just the drawing. Kuprėnaitė lists what tool builders should specify up front, including cumulative pulse count, maximum absorption, allowable reflectance change over the service interval, wavefront requirements and batch-to-batch repeatability. An optic does not need to fail completely to become a process-control concern, she notes; it only needs to change enough that the tool behaves differently from the system that was qualified. Click here to read the full article in Semiconductor Digest magazine. The post Optical Stability Is Becoming a Process-Control Issue appeared first on Semiconductor Digest .