Refractive index database

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Optical constants of CDGM - ZF (Dense flint)

Wavelength: µm

Complex refractive index (n+ik)[ i ]

n   k   LogX   LogY   eV

Derived optical constants

Dispersion formula


Conditions & Spec sheet

n_is_absolute: false
wavelength_is_vacuum: false
temperature: 20.0 °C
  - type: "Schott formula"
    coefficients: 3.7e-06 2.35e-08 -1.53e-10 1.59e-06 6.42e-10 0.278
nd: 1.784724
Vd: 25.754051
glass_code: 785258
glass_status: preferred
density: 4.87 g/cm3
  - temperature_range: -30 70 °C
    coefficient: 7.8e-06 K-1
  - temperature_range: 20 300 °C
    coefficient: 9.6e-06 K-1
dPgF: 0.008
climatic_resistance: 1.0


CDGM Zemax catalog 2022-06 (obtained from
See also CDGM optical glass data sheets


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SF11 optical glass

SF11 is a specialized type of optical glass with a high refractive index and a relatively low Abbe number, indicating higher dispersion properties. This glass type is particularly useful in optical systems where substantial light bending is required, such as in telephoto lenses, high-magnification microscopes, and other compact optical assemblies. However, the high level of dispersion associated with SF11 can result in chromatic aberration, where different wavelengths of light are focused at different points. To correct for this, SF11 is often combined with other glass types that have lower dispersion in complex lens systems, aiming to achieve balanced chromatic correction. Its unique properties make SF11 a popular choice in high-performance optics where both a high refractive index and specific dispersion characteristics are necessary. While SF11 is generally more expensive than more conventional optical glasses like BK7, its specialized attributes make it invaluable in advanced optical designs that demand high levels of performance.

SF11 and similar glasses produced by different makers

Maker Glass
Schott N-SF11
Hikari E-SF11
Sumita K-SFLD11

CDGM Glass Co., Ltd.

CDGM Glass Co., Ltd. is a leading manufacturer of optical glass based in China. The company offers a wide range of optical materials, including various types of crown and flint glasses, which are used in applications ranging from consumer electronics to advanced scientific instruments. Known for their capacity for large-scale production as well as their commitment to quality, CDGM has positioned itself as a major player in both domestic and international markets. Their optical glass products are often used in lenses, prisms, and other optical components that require high precision and reliability. With an extensive catalog that caters to different optical requirements, such as high refractive indices or low dispersion, CDGM serves a diverse clientele including manufacturers of microscopes, telescopes, cameras, and other high-precision optical equipment. The company's expertise in glass science and its ability to provide customized solutions have made it a go-to supplier for businesses seeking high-quality, reliable optical glass.

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Glass is a versatile, amorphous material that has been an essential component in optical technologies for centuries. Comprising mainly of silica along with various additives like soda, lime, or boron, glass can be engineered to exhibit a wide range of optical properties, such as refractive indices and dispersion characteristics. In the optical industry, specialized types of glass like crown, flint, and extra-low dispersion (ED) glasses are used for manufacturing lenses, prisms, and other optical elements. These glasses are precisely formulated to offer specific properties, such as low chromatic aberration or high light transmittance across different spectral ranges. Glass can also be coated with thin layers of materials like anti-reflective coatings to enhance its optical performance. More recently, advances in photonics and nanotechnology have led to the development of innovative glass types, such as photonic crystal and metamaterial glasses, which exhibit unique light-manipulating properties. It is crucial to note that the optical properties of glass, including its refractive index, can vary depending on its composition and temperature, making it important to consult specific data for particular applications. Overall, glass remains a foundational material in optics, its wide applicability owed to its tunable properties and general robustness.

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