আলোকীয় বৰ্ণালীমেতাআলোচক
আলোকীয় সমতল (Assamese)
1. An optical flat is an optical-grade piece of glass lapped and polished to be extremely flat on one or both sides, usually within a few tens of nanometres (billionths of a metre). They are used with a monochromatic... from wikipedia.org