Lens-cementing technology used in optical systems of deep-ultroviolet wavelength regions

In this work, a newly developed optical lens cementing technology is reported. A fluoride material is used as an optical cement that can reduce damage from deep-ultraviolet (DUV) radiation. The degradation of transmittance and the surface quality of the cemented optical elements, including adhesive used for cementing, are evaluated after prolonged DUV irradiation. It is shown that with a 248-nm wavelength, this cement works quite well, up to 1000 h of operation, and the change in transmittance is negligible where average irradiation power is within 27 to 37 mW/cm 2 . Hence for all practical purposes, the use of this cement in microscope objectives is quite acceptable for 248-nm applications, thus confirming that this cementing technology is satisfactory and meets the performance requirement of DUV inspection systems.