Optical constants

Refractive index of Air

Mathar 2007: n 7.5–14.1 µm

Data: tabulated n
Range: 7.5–14.1 µm
Points: 133
Temperature: 288.15 K
Licence: CC0-1.0

Axis Log x Log y

Click the plot to set the calculator wavelength.

At one wavelength

Refractive index n: 1.00027
Extinction coefficient k: 0

Permittivity ε₁: 1.00055
Permittivity ε₂: 0

Absorption coefficient α: 0 cm⁻¹
Penetration depth δ = λ/(2πk): — nm

Abbe number V_d: —
Chromatic dispersion dn/dλ: -1.43003e-09 µm⁻¹

Group index n_g: 1.00027
Group velocity dispersion: — fs²/mm

Dispersion parameter D: — ps/(nm·km)
Photon energy: 0.120373 eV

ε = (n + ik)², α = 4πk/λ, n_g = n − λ dn/dλ, GVD = λ³/(2πc²) d²n/dλ², D = −(λ/c) d²n/dλ². Group-velocity dispersion is given for formula data only.

Use it in Lightsmith

Load this data in Python, simulate in one more line

pip install lightsmith

import lightsmith as ls

# Air: Mathar 2007: n 7.5–14.1 µm
air = ls.fetch_refractiveindex("other", "air", "Mathar-7.5", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(air.range_nm)  # (7500, 14100) nm
eps = air.eps([10300])  # complex permittivity

Downloads the original record once (pinned to the imported snapshot) and caches it.

import json, urllib.request
import lightsmith as ls

url = "https://materials.lightsmith.dev/v1/datasets/ds_1ab3ea83448a/lightsmith"
air = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(air.source)  # citation and provenance travel with the data

Any dataset here, as the library's Tabulated material (air/mathar-2007-7-5).

# ... load air as above, then:
sim = ls.Simulation(
    particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=air)],
    medium_index=1.0,
    wavelengths=ls.WavelengthRange(start_nm=7500, stop_nm=14100, num=81),
)
res = ls.solve(sim)  # exact Mie for a sphere
print(res.q_ext)     # extinction efficiency at each wavelength

Same spec runs with DDA, FDTD, BEM or T-matrix: ls.compare(sim, ["mie", "dda"]).

Materials guide Open a sphere of it in Studio Quick start Ask the community

Lightsmith is open source (MIT): Mie, T-matrix, BEM, DDA, FDTD, RCWA, TMM, mode solvers and inverse design behind one spec, on CPU or GPU. GitHub.

Comments and conditions

Dry air at 15 °C, 101.325 kPa, 370 ppm CO₂ content.

Conditions

temperature: 288.15 K
pressure: 101325

References

R. J. Mathar. Refractive index of humid air in the infrared: model fits. J. Opt. A: Pure Appl. Opt. 9, 470-476 (2007)
[Calculation script (Python) - can be used to calculate the refractive index of air for specific values of humidity, temperature, and pressure]

doi:10.1088/1464-4258/9/5/008 Refractive index of humid air in the infrared: model fits, Journal of Optics A: Pure and Applied Optics (2007)

Cite

Richard J Mathar. Refractive index of humid air in the infrared: model fits. Journal of Optics A: Pure and Applied Optics, 9, 470-476 (2007), doi:10.1088/1464-4258/9/5/008; [Calculation script (Python) - can be used to calculate the refractive index of air for specific values of humidity, temperature, and pressure]; Data from the refractiveindex.info database (M. N. Polyanskiy, Sci. Data 11, 94 (2024), doi:10.1038/s41597-023-02898-2)

Data

133 rows as published

CSV comma separated TXT tab separated YAML n, k Full database record original YAML All quantities CSV JSON metadata

Air, Mathar 2007: n 7.5–14.1 µm: n and k versus wavelength
λ (µm)	n
7.5	1.000272702046
7.55	1.000272700581
7.6	1.000272699435
7.65	1.000272698557
7.7	1.000272697902
7.75	1.00027269743
7.8	1.000272697108
7.85	1.000272696907
7.9	1.0002726968
7.95	1.000272696765
8.0	1.000272696785
8.05	1.000272696842
8.1	1.000272696924
8.15	1.00027269702
8.2	1.000272697119
8.25	1.000272697215
8.3	1.000272697301
8.35	1.000272697373
8.4	1.000272697428
8.45	1.000272697461
8.5	1.000272697473
8.55	1.000272697461
8.6	1.000272697425
8.65	1.000272697365
8.7	1.000272697283
8.75	1.000272697178
8.8	1.000272697053
8.85	1.000272696907
8.9	1.000272696744
8.95	1.000272696564
9.0	1.00027269637
9.05	1.000272696164
9.1	1.000272695947
9.15	1.000272695721
9.2	1.000272695488
9.25	1.000272695251
9.3	1.00027269501
9.35	1.000272694768
9.4	1.000272694527
9.45	1.000272694287
9.5	1.000272694051
9.55	1.000272693819
9.6	1.000272693593
9.65	1.000272693374
9.7	1.000272693164
9.75	1.000272692962
9.8	1.00027269277
9.85	1.000272692588
9.9	1.000272692417
9.95	1.000272692258
10.0	1.00027269211
10.05	1.000272691975
10.1	1.000272691851
10.15	1.000272691739
10.2	1.000272691639
10.25	1.000272691551
10.3	1.000272691474
10.35	1.000272691408
10.4	1.000272691353
10.45	1.000272691308
10.5	1.000272691273
10.55	1.000272691246
10.6	1.000272691227
10.65	1.000272691215
10.7	1.00027269121
10.75	1.00027269121
10.8	1.000272691215
10.85	1.000272691223
10.9	1.000272691233
10.95	1.000272691245
11.0	1.000272691257
11.05	1.000272691267
11.1	1.000272691276
11.15	1.00027269128
11.2	1.00027269128
11.25	1.000272691274
11.3	1.000272691261
11.35	1.000272691239
11.4	1.000272691207
11.45	1.000272691163
11.5	1.000272691107
11.55	1.000272691037
11.6	1.000272690951
11.65	1.000272690849
11.7	1.000272690728
11.75	1.000272690588
11.8	1.000272690427
11.85	1.000272690244
11.9	1.000272690037
11.95	1.000272689805
12.0	1.000272689547
12.05	1.000272689262
12.1	1.000272688948
12.15	1.000272688603
12.2	1.000272688228
12.25	1.000272687819
12.3	1.000272687377
12.35	1.000272686899
12.4	1.000272686385
12.45	1.000272685834
12.5	1.000272685244
12.55	1.000272684614
12.6	1.000272683943
12.65	1.00027268323
12.7	1.000272682473
12.75	1.000272681673
12.8	1.000272680827
12.85	1.000272679934
12.9	1.000272678995
12.95	1.000272678007
13.0	1.000272676969
13.05	1.000272675882
13.1	1.000272674743
13.15	1.000272673552
13.2	1.000272672308
13.25	1.00027267101
13.3	1.000272669658
13.35	1.000272668251
13.4	1.000272666787
13.45	1.000272665266
13.5	1.000272663688
13.55	1.000272662051
13.6	1.000272660355
13.65	1.0002726586
13.7	1.000272656784
13.75	1.000272654907
13.8	1.000272652969
13.85	1.000272650969
13.9	1.000272648906
13.95	1.000272646779
14.0	1.000272644589
14.05	1.000272642335
14.1	1.000272640016

Optical transmission calculator

Free-standing sample in vacuum, normal incidence

Transmittance T: —
Reflectance R: —

Fresnel reflection calculator

R_p: —
R_s: —
R = (R_p+R_s)/2: —
Phase φ_p: —
Phase φ_s: —
Brewster angle θ_B: —
Critical angle θ_C: —

Air: all datasets

About Air

Air is a mixture of gases that constitutes the Earth's atmosphere and is vital for most forms of life on our planet. It primarily consists of nitrogen (approximately 78%) and oxygen (about 21%), with small amounts of other gases such as argon, carbon dioxide, neon, helium, and methane. The exact composition can vary depending on location and environmental conditions. Air is colorless, odorless, and tasteless. From a physical perspective, air plays a crucial role in many processes such as weather patterns, the water cycle, and is also an important medium for sound transmission. In terms of its optical properties, air has a refractive index very close to 1 (approximately 1.0003 at sea level under standard conditions), which varies slightly with temperature, humidity, and pressure. This refractive index is crucial in various applications ranging from astronomical observations to the design of optical systems where light travels through the atmosphere. Understanding the properties of air, including its refractive index, is essential for disciplines such as meteorology, environmental science, aviation, and optical engineering.

More about Air →

Provenance

Version: 1 (snapshot c5c2f18)
Source page: refractiveindex.info
Original file: database/data/other/mixed gases/air/nk/Mathar-7.5.yml
ID: ds_1ab3ea83448a
API: /v1/datasets/ds_1ab3ea83448a

Plot