Editing Binoculars (section)

=== Dielectric mirror ===
{{Main|Dielectric mirror}}

[[image:Dielectric mirror diagram.svg|thumb|right|Diagram of a dielectric mirror. Thin layers with a high refractive index ''n''<sub>1</sub> are interleaved with thicker layers with a lower refractive index ''n''<sub>2</sub>. The path lengths ''l''<sub>A</sub> and ''l''<sub>B</sub> differ by exactly one wavelength, which leads to constructive interference.]]

Dielectric coatings are used in [[Schmidt–Pechan prism|Schmidt–Pechan]] and [[Uppendahl prism|Uppendahl]] roof prisms to cause the prism surfaces to act as a [[dielectric mirror]]. This coating was introduced in 2004 in Zeiss Victory FL binoculars featuring Schmidt–Pechan prisms. Other manufacturers followed soon, and since then dielectric coatings are used across the board in medium and high-quality Schmidt–Pechan and Uppendahl roof prism binoculars. The non-metallic [[dielectric]] reflective coating is formed from several multilayers of alternating high and low [[refractive index]] materials deposited on a prism's reflective surfaces. The manufacturing techniques for dielectric mirrors are based on [[thin-film deposition]] methods. A common application technique is [[physical vapor deposition]] which includes [[evaporative deposition]] with maybe seventy or more different superimposed vapor coating layers deposits, making it a complex production process.<ref>{{Cite web |url=https://www.walter-schwab.com/lesenswert/05-optikbuch-jagd-und-beobachtung/ |title=Optik für Jagd und Naturbeobachtung, Carl Zeiss Sports Optics / Walter J. Schwab, 2. Ausgabe- Wetzlar - 2017, page 45 |access-date=2022-11-22 |archive-date=2022-11-22 |archive-url=https://web.archive.org/web/20221122114032/https://www.walter-schwab.com/lesenswert/05-optikbuch-jagd-und-beobachtung/ |url-status=live }}</ref> This multilayer coating increases reflectivity from the prism surfaces by acting as a [[distributed Bragg reflector]]. A well-designed multilayer dielectric coating can provide a [[reflectivity]] of over 99% across the [[visible spectrum|visible light spectrum]].<ref>{{cite journal |first1=ZenaE. |last1=Slaiby |first2=Saeed N. |last2=Turki |title=Study the reflectance of dielectric coating for the visiblespectrum |journal=International Journal of Emerging Trends & Technology in Computer Science |volume=3 |issue=6 |date=November–December 2014 |pages=1–4 |issn=2278-6856 |url=https://www.ijettcs.org/Volume3Issue6/IJETTCS-2014-10-30-4.pdf |access-date=2022-11-21 |archive-date=2022-11-28 |archive-url=https://web.archive.org/web/20221128114127/https://www.ijettcs.org/Volume3Issue6/IJETTCS-2014-10-30-4.pdf |url-status=live }}</ref> This reflectivity is an improvement compared to either an aluminium mirror coating or silver mirror coating.

Porro prism and Perger prism binoculars and roof prism binoculars using the Abbe–Koenig roof prism do not use dielectric coatings because these prisms reflect with 100% reflectivity using [[total internal reflection]] in the prism rather than requiring a (dielectric) mirror coating.