Refractive index database

nk database   |   n2 database   |   about




Optical constants of LIQUIDS
Water (H2O)

Wavelength: µm

Complex refractive index (n+ik)[ i ]

n   k   LogX   LogY   eV

Derived optical constants

Conditions & Spec sheet

n_is_absolute: true
wavelength_is_vacuum: true
temperature: 25 °C


Liquid water (H2O) at 25 °C


G. M. Hale and M. R. Querry. Optical constants of water in the 200-nm to 200-µm wavelength region, Appl. Opt. 12, 555-563 (1973)
See also Segelstein 1981 for more recent data from the same group.


[CSV - comma separated]   [TXT - tab separated]   [Full database record]


Water and ice, H2O

Water (H2O) is the most abundant compound on Earth's surface. It exists in various states—liquid, solid (ice), and gas (water vapor)—each having unique optical properties. In its liquid form, water is transparent over a broad range of visible wavelengths but absorbs infrared and ultraviolet light. It serves as the basis for many solvents used in optical spectroscopy. Ice, the solid state of water, also has specific optical characteristics like birefringence and is studied for its role in atmospheric optics. Water vapor, on the other hand, can act as a selective absorber of certain wavelengths and is significant in remote sensing applications. Given its ubiquity and importance in life sciences and environmental science, understanding the optical properties of water and its various states is crucial.

External links


Liquids play a unique and often underappreciated role in optical systems, offering a set of properties that can complement or replace those of solid materials like glass and crystals. With variable density, temperature-dependent refractive indices, and the ability to flow and fill spaces, liquids are employed in applications ranging from simple lenses to complex adaptive optical elements. Common types of optical liquids include oils, water, and specialty fluids engineered for high refractive index or low dispersion. Liquids are particularly useful in adjustable lenses, interferometers, and optical tweezers, as they allow for dynamic control of optical characteristics. Some advanced liquid systems, such as liquid crystals, can even undergo phase transitions that drastically change their optical behavior, making them valuable in display technologies and variable optical attenuators. It's worth noting that the optical properties of liquids, like refractive index and absorption, can vary significantly with temperature, pressure, and chemical composition, making calibration and environmental control crucial for precise applications. Liquids are also generally more susceptible to impurities and environmental factors like evaporation, requiring sealed or controlled systems for long-term reliability. Overall, liquids offer a versatile and dynamic set of options for optical engineers, providing opportunities for innovative solutions in both established and emerging optical technologies.

External links