What is this ISO 12123 - Optics and photonics — Specification of raw optical glass about?
ISO 12123 gives rules for the specification of raw optical glass. It serves as a complement to the ISO 10110 series, which provides rules specifying finished optical elements. Since raw optical glass can be quite different in shape and size from the optical elements, its specification also differs from that of optical elements.
ISO 12123 introduces definitions, reference formulae and data needed for calculating the deviation of the relative partial dispersion from the normal line. This quantity serves to value the suitability of optical glasses for colour aberration correction beyond achromatic correction of only two colours.
The intent of ISO 12123 is to address the specific needs of raw optical glass, many of the parameters and characteristics are common to other optical materials, which are not necessarily glass.
ISO 12123 can be used for non-glass materials, the user is informed that only optical glass has been considered in the development of this document, and other materials can have issues, which have not been taken into consideration.
Who is ISO 12123 - Optics and photonics — Specification of raw optical glass for?
ISO 12123 on optics and photonics is useful for:
- Glass manufacturers and suppliers
- Optical element manufacturers
- Regulatory bodies
- Certification bodies
Why should you use ISO 12123 - Optics and photonics — Specification of raw optical glass?
Raw optical glass comes as strip glass, pressings block glass or large castings. Its characteristics are widely the same as those for optical elements such as lenses and prisms. Homogeneity tolerances increase requirements on quality strongly.
ISO 12123 provides guidelines for the essential specification characteristics of raw optical glass in order to improve communication between glass suppliers and optical element manufacturers. For specific applications (e.g., lasers, the infrared spectral range), specifications based on this document need supplements.
ISO 12123 introduces grade denominations for tolerance limits for the main properties of optical raw glass. The characteristics colour code and UV cut-off edge are different possibilities to describe position and slope of the UV-transmission edge of optical glasses.
ISO 12123 explains and gives recommendations for applying the document in ways which avoid over-specification and its unfavourable consequences.
What’s changed since the last update?
BS ISO 12123:2018 supersedes BS ISO 12123:2010. BS ISO 12123:2018 includes some technical changes with respect to BS ISO 12123:2010. These include:
- Definition of relative partial dispersion and its deviation from normal line and definition of internal transmittance have been added
- Grade abbreviations at all tolerances in Clause 4 have been added
- All abbreviations have been written with two capital letters with relation to characteristics’ names
- In 4.6, an indication for required minimum aperture has been added and in 4.7, striae indication for two and three perpendicular inspection directions has been added
- For partial dispersion and its deviation from normal line, the following has been added: dispersion data for standard crown and flint glass for normal environment, general formula for normal lines for the relative partial dispersions for any wavelength pairs, examples for six specific line pairs in Clause 5 and a calculation method and data for calculating dispersion data at temperatures other than 20 °C
- In Clause 6, Example 1 for specification of optical raw glass with tolerances grades has been introduced and extended by adding a second case
