Optical constants
Refractive index of Kapton
Smith and Loewenstein 1975: n,k 28.6–182 µm
- Data
- tabulated n + tabulated k
- Range
- 28.57–181.8 µm
- Points
- 60
- Licence
- CC0-1.0
Plot
Click the plot to set the calculator wavelength. Note: k data cover 28571.4-166667 nm only; k = 0 elsewhere in the n range 28571.4-181818 nm.
At one wavelength
- Refractive index n
- 1.81772
- Extinction coefficient k
- 0.0588351
- Permittivity ε1
- 3.30063
- Permittivity ε2
- 0.213891
- Absorption coefficient α
- 102.544 cm⁻¹
- Penetration depth δ = λ/(2πk)
- 195038 nm
- Abbe number Vd
- —
- Chromatic dispersion dn/dλ
- -0.003402 µm⁻¹
- Group index ng
- 2.063
- Group velocity dispersion
- — fs²/mm
- Dispersion parameter D
- — ps/(nm·km)
- Photon energy
- 0.0171961 eV
ε = (n + ik)², α = 4πk/λ, ng = 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
# Kapton: Smith and Loewenstein 1975: n,k 28.6–182 µm
kapton = ls.fetch_refractiveindex("other", "Kapton", "Smith", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(kapton.range_nm) # (28571.4, 181818) nm
eps = kapton.eps([72100]) # complex permittivityDownloads 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_ba08ac345cd3/lightsmith"
kapton = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(kapton.source) # citation and provenance travel with the dataAny dataset here, as the library's Tabulated material (kapton/smith-loewenstein-1975).
# ... load kapton as above, then:
sim = ls.Simulation(
particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=kapton)],
medium_index=1.0,
wavelengths=ls.WavelengthRange(start_nm=28570, stop_nm=181800, num=81),
)
res = ls.solve(sim) # exact Mie for a sphere
print(res.q_ext) # extinction efficiency at each wavelengthSame spec runs with DDA, FDTD, BEM or T-matrix: ls.compare(sim, ["mie", "dda"]).
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
- k data cover 28571.4-166667 nm only; k = 0 elsewhere in the n range 28571.4-181818 nm
References
- doi:10.1364/ao.14.001335 Optical constants of far infrared materials 3: plastics, Applied Optics (1975)
Cite
Donald R. Smith and Ernest V. Loewenstein. Optical constants of far infrared materials 3: plastics. Applied Optics, 14, 1335 (1975), doi:10.1364/ao.14.001335; Data from the refractiveindex.info database (M. N. Polyanskiy, Sci. Data 11, 94 (2024), doi:10.1038/s41597-023-02898-2)
Data
Computed on 60 wavelengths, the same grid as the API and the library| λ (µm) | n | k |
|---|---|---|
| 28.5714 | 1.754 | 0.0091 |
| 28.9855 | 1.751 | 0.0098 |
| 29.4118 | 1.748 | 0.0114 |
| 29.8507 | 1.746 | 0.0115 |
| 30.303 | 1.745 | 0.0129 |
| 30.7692 | 1.742 | 0.0134 |
| 31.25 | 1.743 | 0.0122 |
| 31.746 | 1.74 | 0.0107 |
| 32.2581 | 1.739 | 0.0101 |
| 32.7869 | 1.736 | 0.00994 |
| 33.3333 | 1.734 | 0.0105 |
| 33.8983 | 1.733 | 0.012 |
| 34.4828 | 1.73 | 0.014 |
| 35.0877 | 1.728 | 0.0161 |
| 35.7143 | 1.723 | 0.0186 |
| 36.3636 | 1.716 | 0.0247 |
| 37.037 | 1.712 | 0.03357 |
| 37.7358 | 1.721 | 0.03784 |
| 38.4615 | 1.733 | 0.1139 |
| 39.2157 | 1.745 | 0.04865 |
| 40 | 1.758 | 0.0306 |
| 40.8163 | 1.758 | 0.026 |
| 41.6667 | 1.749 | 0.0219 |
| 42.5532 | 1.743 | 0.0201 |
| 43.4783 | 1.737 | 0.0209 |
| 44.4444 | 1.723 | 0.0217 |
| 45.4545 | 1.729 | 0.0255 |
| 46.5116 | 1.726 | 0.027 |
| 47.619 | 1.725 | 0.0337 |
| 48.7805 | 1.726 | 0.03967 |
| 50 | 1.73 | 0.04074 |
| 51.2821 | 1.73 | 0.0386 |
| 52.6316 | 1.726 | 0.0408 |
| 54.0541 | 1.723 | 0.0419 |
| 55.5556 | 1.716 | 0.04523 |
| 57.1429 | 1.709 | 0.0583 |
| 58.8235 | 1.723 | 0.0946 |
| 60.6061 | 1.738 | 0.1227 |
| 62.5 | 1.755 | 0.1092 |
| 64.5161 | 1.792 | 0.08784 |
| 66.6667 | 1.793 | 0.08143 |
| 68.9655 | 1.808 | 0.08029 |
| 71.4286 | 1.82 | 0.06184 |
| 74.0741 | 1.811 | 0.05 |
| 76.9231 | 1.815 | 0.0437 |
| 80 | 1.805 | 0.0376 |
| 83.3333 | 1.806 | 0.0342 |
| 86.9565 | 1.804 | 0.0341 |
| 90.9091 | 1.805 | 0.0305 |
| 95.2381 | 1.808 | 0.0244 |
| 100 | 1.804 | 0.0186 |
| 105.263 | 1.806 | 0.0134 |
| 111.111 | 1.797 | 0.0084 |
| 117.647 | 1.793 | 0.0078 |
| 125 | 1.787 | 0.0095 |
| 133.333 | 1.785 | 0.0083 |
| 142.857 | 1.784 | 0.0085 |
| 153.846 | 1.781 | 0.0092 |
| 166.667 | 1.77 | 0.0041 |
| 181.818 | 1.769 | 0 |
Optical transmission calculator
Free-standing sample in vacuum, normal incidence- Transmittance T
- —
- Reflectance R
- —
Fresnel reflection calculator
- Rp
- —
- Rs
- —
- R = (Rp+Rs)/2
- —
- Phase φp
- —
- Phase φs
- —
- Brewster angle θB
- —
- Critical angle θC
- —
Polyimide manufactured by DuPont under the name Kapton.