In the late 1800s, German physicist Ernst Abbe, a colleague of Carl Zeiss, created the Abbe number, a measure of the magnitude of chromatic dispersion for the visible spectrum. [9] Also known as the V-number, the Abbe number combines the refractive indices of a material at three wavelengths (486.1 nm blue from hydrogen, 589.2 nm yellow from sodium, and 656.3 nm red from hydrogen) to approximate the amount of chromatic aberration a material will have when visible light passes through it (Figure 3). [8] The Abbe number is inversely related to the amount of chromatic aberration. A high Abbe number indicates low chromatic aberration, and a low Abbe number indicates high chromatic aberration. ABBA are one of the greatest pop outfits in history. Their blend of lush orchestrations and light, bouncy europop was both unique and commercially appealing, taking much of the world by storm. Nonetheless, more than 40 years after the band broke up, millennials continue to stream, boogie and replicate ABBA’s expressive and colourful clothing —perhaps courtesy of the films, an appreciation for retro fashion and general chatter on social media. Oh and also the fact that they released new, and groundbreaking, music over the past year. Therefore, it should come as little surprise that ABBA has been nominated for two of the top categories at the 2023 Grammys —Record of the Year category, for ‘Don’t Shut Me Down’ and Album of the Year for Voyages. While they face some stiff (and equally stylish) competition, including Adele, Beyoncé, Harry Styles, Lizzo and more —I certainly think ABBA’s in for a good chance. Please ‘Take A Chance’ on them Recording Academy? But like most groovy looks from the disco era, ABBA was at the forefront. They sang about ‘Dancing Queen'[s] after all. Paschotta, Rüdiger. Encyclopedia of Laser Physics and Technology: Optical Glasses. Wiley-VCH, 2008.

Wang, L; Oku, H; Ishikawa, M. “An adaptive achromatic doublet design by double variable focus lenses”. Novel Optical Systems Design and Optimization XVII(2014). doi:10.1117/12.2061203. Nave, Carl Rod. "Refraction of Light". Hyperphysics - Georgia State University, 2009. hyperphysics.phy-astr.gsu.edu/hbase/geoopt/refr.html.Günther, Norbert. “Abbe, Ernst”. Dictionary of Scientific Biography. Charles Scribner’s Sons. New York, NY, 1970. Specific gravity is a ratio of a material’s density to the density of water at 4 degrees Celsius. Density and specific gravity can both compare substances in terms to the amount of mass per unit volume. Density is simply mass per unit volume, however specific gravity is a ratio and thus has no units. A lens with a low specific gravity means that an identically sized lens of a high specific gravity would be heavier. This property is relevant in designing lenses as a lighter lens is preferable for eyeglass wearers. [16] Ultraviolet Absorption Step into the spotlight and transform into a bona fide 'Super Trooper' when you take center stage as the 'Dancing Queen' at any 70's themed soirée! Their meteoric rise was sparked by their famed Eurovision performance of original song “Waterloo”, which caused them to win the 1974 competition in Sweden. Step into the world of ABBA's "Voyage" with our dancing queen costumes. As the legendary band makes their spectacular return, it's your chance to don attire inspired by their latest album and concert visuals.

Mellish, Bob. "Chromatic aberration lens diagram". 6 March 2006. https://upload.wikimedia.org/wikipedia/commons/a/aa/Chromatic_aberration_lens_diagram.svg. Celebrate the timeless style of ABBA with outfits that pay homage to their unparalleled legacy and their exciting new chapter. Join the voyage and shine on the dance floor!This compound lens can be optimized at a distance of either two wavelengths (achromatic lens), three wavelengths (apochromatic lens), or four wavelengths (superachromatic lens). [14] This point of optimization where chromatic aberration is minimized is called the circle of least confusion. [15] The achromatic lens is the most commonly used commercial lens, referred to as a doublet, and can drastically reduce the chromatic focal shift. [13] Specific Gravity