Super-smooth optical polishing facility at HELOD, RRCAT has been established with the objective to produce large size, flat ultra smooth optical glass and glass-ceramic substrates for indigenous development of thin-film / Sol-gel coated high LIDT, high reflectivity (HR) mirrors and high transmission windows for high energy Nd-Glass laser chain. Bowl-feed chemical-mechanical polishing using conventional polishing machines are used for producing these ultra-smooth substrates. Optical substrates up to 150 mm with r.m.s surface roughness below 5 Å and flatness /10 are being regularly produced at HELOD which are used to make high quality laser optics. High LIDT HR mirrors with 99.8% reflectivity and windows having 99.5% transmission at 1053nm have already been developed in-house. LIDT of 13 J/cm2 and 20 J/cm2 at 1053 nm with 5 ns pulses have been achieved so far with thin-film and Sol-gel AR coating respectively. These ultra-low roughness substrates are also being used to indigenously develop PZT actuated synchrotron x-ray deformable mirrors. Highly polished copper mirrors developed at HELOD are also used in IR-FEL beam transport line of RRCAT.
Photos of Thin-film/Sol-gel AR coated windows and thin-film coated HR mirrors for high-energy Nd-glass laser
Photos of Large, flat super-smooth Fused Silica Substrates developed
