ISO 7944 pdf download

ISO 7944 pdf download.Optics and optical instruments — Reference wavelengths 1 Scope This International Standard specifies two reference wavelengths to be used for the characterization of optical materials, optical systems and instruments, as well as ophthalmic lenses. It defines the associated principal refractive indices and principal dispersions, as well as the Abbe numbers with regard to these reference wavelengths and principal dispersions. 2 Reference wavelengths, principal dispersions and Abbe numbers 2.1 General The reference wavelengths are the mercury e-line 546,07 nm (see 2.2) and the helium d-line 587,56 nm (see 2.3). For non-ophthalmic applications the mercury e-line shall be the reference wavelength. Other wavelengths which may be used in addition to these reference wavelengths are given in tables 1 , 2 and 3. NOTE For the future, it is envisaged that only one reference wavelength is to be specified, even for ophthalmic use. 2.2 Mercury e-line 546,07 nm