Refractive index database

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Optical constants of BK7

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: 3.25479e-06 0.0 0.0 0.0 0.0 0.0
nd: 1.51680
Vd: 64.20
glass_code: 517642
density: 2.52 g/cm3
  - temperature_range: -30 70 °C
    coefficient: 7.6e-06 K-1
  - temperature_range: 20 300 °C
    coefficient: 9.3e-06 K-1
dPgF: 0.0016
climatic_resistance: 3.0
stain_resistance: 1.0
acid_resistance: 1.0


General glass Type


HOYA Zemax catalog 2017-04-01 (obtained from


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HOYA Corporation

HOYA Corporation is a global technology company based in Japan, known for its diverse range of products in the fields of healthcare and optics. In the optical industry, HOYA is particularly recognized for its high-quality optical glass and lens technologies. The company produces a wide array of optical products, from eyeglass lenses with advanced coatings to specialized glass materials used in cameras, telescopes, and other precision optical instruments. HOYA's expertise extends to various types of optical glass, including low-dispersion and high-refractive-index materials, which find applications in situations requiring exceptional optical clarity and performance. Beyond its contributions to optics, HOYA has also ventured into medical technologies, making it a multi-faceted company with a broad impact. With a commitment to innovation and quality, HOYA has earned a reputation as a leader in its field, consistently delivering products that set industry standards for performance and reliability. Their expansive portfolio and technological prowess make them a go-to provider for both consumer and industrial optical solutions.

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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

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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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