Refractive index database

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Optical constants of BAK1

Wavelength: µm

Complex refractive index (n+ik)[ i ]

n   k   LogX   LogY   eV

Derived optical constants

Dispersion formula [ i ]


Conditions & Spec sheet

n_is_absolute: false
wavelength_is_vacuum: false
temperature: 20.0 °C
  - type: "Schott formula"
    coefficients: 6.29e-08 1.64e-08 -1.82e-11 4.71e-07 4.87e-10 0.223
nd: 1.572500
Vd: 57.486797
glass_code: 573575
density: 3.18 g/cm3
  - temperature_range: -30 70 °C
    coefficient: 7.4e-06 K-1
  - temperature_range: 20 300 °C
    coefficient: 8.9e-06 K-1
dPgF: -0.001
climatic_resistance: 2.0


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


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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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BAK1 optical glass

BAK1 (Borosilicate Crown 1) is a type of optical glass that combines boron and silicate, among other elements, to achieve specific optical properties. This glass type is often used in specialized optical applications that require low dispersion and a high refractive index. BAK1 is known for its good transmission across the visible spectrum and into the near-infrared range, making it suitable for a variety of optical devices like telescopes, binoculars, and certain types of lenses. Its low level of optical aberrations makes it a choice material for high-quality imaging systems. Like other high-quality optical glasses, BAK1 can be expensive and is generally used in applications where its particular optical characteristics offer a noticeable advantage. Overall, BAK1 represents a specialized category of optical glass, designed for applications requiring high performance and specific optical properties.

BAK1 or similar glasses produced by different makers

Maker Glass
Schott N-BAK1
Hikari E-BAK1
Ohara S-BAL11


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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