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Optical constants of BK7
H-K9L (CDGM)

Wavelength: µm
 (0.290–2.400)  
 

Complex refractive index (n+ik)[ i ]


n   k   LogX   LogY   eV

Derived optical constants

Dispersion formula [ i ]

$$n^2-1=\frac{0.614555251λ^2}{λ^2-0.0145987884}+\frac{0.656775017λ^2}{λ^2-0.00287769588}+\frac{1.02699346λ^2}{λ^2-107.653051}$$

Conditions & Spec sheet

n_is_absolute: false
wavelength_is_vacuum: false
temperature: 20.0 °C
thermal_dispersion:
  - type: "Schott formula"
    coefficients: -1.04e-06 1.48e-08 -5.17e-11 3.85e-07 4.55e-10 0.211
nd: 1.516800
Vd: 64.198732
glass_code: 517642
glass_status: standard
density: 2.52 g/cm3
thermal_expansion:
  - temperature_range: -30 70 °C
    coefficient: 7.6e-06 K-1
  - temperature_range: 20 300 °C
    coefficient: 9.5e-06 K-1
dPgF: -0.0005
climatic_resistance: 2.0

References

CDGM Zemax catalog 2022-06 (obtained from http://www.cdgmgd.com)
See also CDGM optical glass data sheets

Data

[Expressions for n]   [CSV - comma separated]   [TXT - tab separated]   [Full database record]

INFO

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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BK7 optical glass

BK7 is a widely used optical glass known for its high transmission and clear, colorless appearance. Composed primarily of silica and boron oxide, BK7 is popular in a broad range of optical applications, including lenses, prisms, and windows. It exhibits good mechanical properties and can be easily polished to a high optical quality. While it is not as resistant to thermal shock or chemical corrosion as some specialized glasses like borosilicate or fused silica, it is considerably less expensive, making it a cost-effective choice for many applications. Its relatively high refractive index and low dispersion make it suitable for a variety of optical systems, particularly those operating in the visible spectrum. Because of its versatility and cost-effectiveness, BK7 is often considered the "go-to" material for general-purpose optical components.

Analogs of BK7 glass produced by different makers

Maker Glass
SCHOTT N-BK7
OHARA S-BSL7
HIKARI J-BK7A
CDGM H-K9L
HOYA BSC7
SUMITA K-BK7
LZOS K8

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Glass

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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