Optical constants

Refractive index of NaF (Sodium fluoride)

Li 1976: n 0.15–17 µm

Data: formula 1
Range: 0.15–17 µm
Licence: CC0-1.0

Axis Log x Log y

Click the plot to set the calculator wavelength.

At one wavelength

Refractive index n: 1.32531
Extinction coefficient k: 0

Permittivity ε₁: 1.75644
Permittivity ε₂: 0

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

Abbe number V_d: 88.288
Chromatic dispersion dn/dλ: -0.0189553 µm⁻¹

Group index n_g: 1.33644
Group velocity dispersion: 34.4011 fs²/mm

Dispersion parameter D: -187.676 ps/(nm·km)
Photon energy: 2.11001 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

# NaF (Sodium fluoride): Li 1976: n 0.15–17 µm
naf = ls.fetch_refractiveindex("main", "NaF", "Li", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(naf.range_nm)  # (150, 17000) nm
eps = naf.eps([633])  # 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_be3996eeed94/lightsmith"
naf = ls.Tabulated.model_validate(json.load(urllib.request.urlopen(url)))
print(naf.source)  # citation and provenance travel with the data

Any dataset here, as the library's Tabulated material (naf/li-1976).

# ... load naf as above, then:
sim = ls.Simulation(
    particles=[ls.Particle(shape=ls.Sphere(radius_nm=50), material=naf)],
    medium_index=1.0,
    wavelengths=ls.WavelengthRange(start_nm=400, stop_nm=1000, 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"]).

import json, urllib.request
import lightsmith as ls

url = "https://materials.lightsmith.dev/v1/datasets/ds_be3996eeed94/lightsmith?model=drude_lorentz"
naf_dl = ls.DrudeLorentz.model_validate(json.load(urllib.request.urlopen(url)))

A dispersive Drude–Lorentz model for time-domain solvers.

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.

Dispersion formula

Sellmeier (formula 1), λ in µm

n^{2} - 1 = 0.41572 + \frac{0.32785 λ^{2}}{λ^{2} - {0.117}^{2}} + \frac{3.18248 λ^{2}}{λ^{2} - {40.57}^{2}}

Valid from 0.15 to 17.0 µm.

Coefficients as stored

C_i	Value
C1	0.41572
C2	0.32785
C3	0.117
C4	3.18248
C5	40.57

Comments and conditions

297 K (24 °C).

References

H. H. Li. Refractive index of alkali halides and its wavelength and temperature derivatives. J. Phys. Chem. Ref. Data 5, 329-528 (1976) and references therein.
* Sellmeier formula is derived by critical analysis of experimental data from several sources.

doi:10.1063/1.555536 Refractive index of alkali halides and its wavelength and temperature derivatives, Journal of Physical and Chemical Reference Data (1976)

Cite

H. H. Li. Refractive index of alkali halides and its wavelength and temperature derivatives. Journal of Physical and Chemical Reference Data, 5, 329-528 (1976), doi:10.1063/1.555536; Data from the refractiveindex.info database (M. N. Polyanskiy, Sci. Data 11, 94 (2024), doi:10.1038/s41597-023-02898-2)

Data

Computed on 400 wavelengths, the same grid as the API and the library

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

NaF (Sodium fluoride), Li 1976: n 0.15–17 µm: n and k versus wavelength
λ (µm)	n
0.15	1.500961
0.151789	1.491132
0.153599	1.482121
0.155431	1.473832
0.157285	1.466182
0.15916	1.459103
0.161059	1.452534
0.162979	1.446424
0.164923	1.440728
0.16689	1.435405
0.16888	1.430423
0.170894	1.42575
0.172932	1.421359
0.174995	1.417227
0.177082	1.413333
0.179194	1.409658
0.181331	1.406184
0.183493	1.402896
0.185682	1.399781
0.187896	1.396826
0.190137	1.39402
0.192405	1.391353
0.194699	1.388814
0.197021	1.386397
0.199371	1.384092
0.201749	1.381893
0.204155	1.379793
0.206589	1.377787
0.209053	1.375868
0.211546	1.374032
0.214069	1.372273
0.216622	1.370588
0.219206	1.368972
0.22182	1.367422
0.224465	1.365933
0.227142	1.364504
0.229851	1.36313
0.232592	1.361809
0.235366	1.360539
0.238173	1.359316
0.241014	1.358139
0.243888	1.357004
0.246797	1.355912
0.24974	1.354858
0.252718	1.353842
0.255732	1.352861
0.258782	1.351915
0.261869	1.351002
0.264992	1.350119
0.268152	1.349267
0.27135	1.348443
0.274586	1.347647
0.277861	1.346877
0.281174	1.346132
0.284528	1.345411
0.287921	1.344714
0.291355	1.344039
0.294829	1.343385
0.298346	1.342752
0.301904	1.342138
0.305504	1.341544
0.309148	1.340968
0.312835	1.340409
0.316565	1.339868
0.320341	1.339342
0.324161	1.338833
0.328027	1.338339
0.331939	1.337859
0.335898	1.337393
0.339904	1.336942
0.343958	1.336503
0.34806	1.336077
0.352211	1.335663
0.356411	1.335261
0.360662	1.33487
0.364963	1.334491
0.369315	1.334122
0.37372	1.333763
0.378177	1.333415
0.382687	1.333076
0.387251	1.332746
0.391869	1.332426
0.396543	1.332114
0.401272	1.331811
0.406058	1.331516
0.4109	1.331229
0.415801	1.330949
0.420759	1.330677
0.425777	1.330413
0.430855	1.330155
0.435994	1.329904
0.441193	1.329659
0.446455	1.329421
0.451779	1.329189
0.457167	1.328964
0.46262	1.328743
0.468137	1.328529
0.47372	1.32832
0.479369	1.328116
0.485086	1.327918
0.490872	1.327724
0.496726	1.327535
0.50265	1.327351
0.508644	1.327172
0.51471	1.326997
0.520849	1.326826
0.52706	1.32666
0.533346	1.326497
0.539707	1.326339
0.546143	1.326184
0.552657	1.326033
0.559248	1.325885
0.565917	1.325741
0.572667	1.325601
0.579496	1.325463
0.586407	1.325329
0.593401	1.325198
0.600478	1.32507
0.607639	1.324945
0.614886	1.324823
0.622219	1.324703
0.629639	1.324586
0.637149	1.324472
0.644747	1.32436
0.652437	1.324251
0.660217	1.324144
0.668091	1.324039
0.676059	1.323937
0.684122	1.323836
0.69228	1.323738
0.700537	1.323642
0.708891	1.323548
0.717346	1.323456
0.725901	1.323365
0.734558	1.323276
0.743318	1.323189
0.752183	1.323104
0.761153	1.323021
0.770231	1.322938
0.779417	1.322858
0.788712	1.322779
0.798118	1.322701
0.807637	1.322625
0.817269	1.32255
0.827015	1.322476
0.836878	1.322403
0.846859	1.322332
0.856959	1.322262
0.867179	1.322193
0.877521	1.322125
0.887986	1.322058
0.898576	1.321992
0.909293	1.321927
0.920137	1.321862
0.931111	1.321799
0.942215	1.321736
0.953452	1.321675
0.964823	1.321613
0.976329	1.321553
0.987973	1.321493
0.999756	1.321434
1.01168	1.321376
1.02374	1.321318
1.03595	1.321261
1.04831	1.321204
1.06081	1.321147
1.07346	1.321091
1.08626	1.321036
1.09922	1.32098
1.11233	1.320925
1.12559	1.320871
1.13902	1.320816
1.1526	1.320762
1.16635	1.320708
1.18026	1.320654
1.19433	1.320601
1.20858	1.320547
1.22299	1.320494
1.23758	1.32044
1.25233	1.320387
1.26727	1.320333
1.28238	1.32028
1.29768	1.320226
1.31315	1.320173
1.32881	1.320119
1.34466	1.320065
1.3607	1.320011
1.37693	1.319956
1.39335	1.319901
1.40996	1.319846
1.42678	1.319791
1.4438	1.319735
1.46101	1.319679
1.47844	1.319623
1.49607	1.319566
1.51391	1.319508
1.53197	1.31945
1.55024	1.319392
1.56873	1.319333
1.58743	1.319273
1.60637	1.319212
1.62552	1.319151
1.64491	1.319089
1.66453	1.319027
1.68438	1.318963
1.70447	1.318899
1.72479	1.318834
1.74536	1.318768
1.76618	1.318701
1.78724	1.318633
1.80856	1.318564
1.83013	1.318494
1.85195	1.318423
1.87404	1.31835
1.89639	1.318277
1.919	1.318202
1.94189	1.318126
1.96505	1.318049
1.98848	1.31797
2.0122	1.31789
2.0362	1.317808
2.06048	1.317725
2.08505	1.317641
2.10992	1.317555
2.13508	1.317467
2.16055	1.317377
2.18631	1.317286
2.21239	1.317193
2.23877	1.317098
2.26547	1.317001
2.29249	1.316902
2.31983	1.316802
2.3475	1.316699
2.37549	1.316594
2.40382	1.316486
2.43249	1.316377
2.4615	1.316265
2.49086	1.316151
2.52056	1.316034
2.55062	1.315915
2.58104	1.315793
2.61182	1.315669
2.64297	1.315542
2.67449	1.315412
2.70639	1.315279
2.73867	1.315143
2.77133	1.315004
2.80438	1.314862
2.83782	1.314717
2.87167	1.314568
2.90591	1.314416
2.94057	1.314261
2.97564	1.314102
3.01113	1.31394
3.04704	1.313773
3.08338	1.313603
3.12015	1.313429
3.15736	1.313251
3.19502	1.313069
3.23312	1.312882
3.27168	1.312691
3.3107	1.312496
3.35018	1.312296
3.39013	1.312091
3.43056	1.311881
3.47148	1.311667
3.51288	1.311447
3.55477	1.311222
3.59717	1.310992
3.64007	1.310756
3.68348	1.310515
3.72741	1.310267
3.77186	1.310014
3.81684	1.309755
3.86236	1.30949
3.90843	1.309218
3.95504	1.308939
4.00221	1.308654
4.04994	1.308362
4.09824	1.308063
4.14711	1.307756
4.19657	1.307442
4.24662	1.30712
4.29726	1.306791
4.34851	1.306453
4.40037	1.306107
4.45285	1.305753
4.50596	1.30539
4.5597	1.305018
4.61408	1.304637
4.6691	1.304246
4.72479	1.303846
4.78113	1.303436
4.83815	1.303015
4.89585	1.302585
4.95424	1.302143
5.01333	1.301691
5.07312	1.301227
5.13362	1.300751
5.19484	1.300264
5.2568	1.299765
5.31949	1.299253
5.38293	1.298728
5.44713	1.29819
5.51209	1.297638
5.57783	1.297073
5.64435	1.296493
5.71166	1.295899
5.77978	1.295289
5.84871	1.294664
5.91846	1.294023
5.98904	1.293366
6.06047	1.292692
6.13275	1.292001
6.20589	1.291292
6.2799	1.290565
6.35479	1.289819
6.43058	1.289054
6.50727	1.28827
6.58488	1.287465
6.66341	1.286639
6.74288	1.285791
6.82329	1.284922
6.90467	1.28403
6.98701	1.283115
7.07034	1.282176
7.15466	1.281212
7.23999	1.280223
7.32633	1.279207
7.4137	1.278165
7.50212	1.277096
7.59159	1.275997
7.68213	1.27487
7.77375	1.273713
7.86646	1.272524
7.96027	1.271304
8.05521	1.270051
8.15127	1.268764
8.24849	1.267442
8.34686	1.266084
8.4464	1.26469
8.54713	1.263257
8.64907	1.261785
8.75222	1.260272
8.8566	1.258718
8.96222	1.257121
9.0691	1.255479
9.17726	1.253792
9.28671	1.252057
9.39746	1.250273
9.50954	1.248439
9.62295	1.246553
9.73771	1.244614
9.85384	1.242619
9.97136	1.240567
10.0903	1.238455
10.2106	1.236283
10.3324	1.234047
10.4556	1.231746
10.5803	1.229377
10.7065	1.226938
10.8342	1.224427
10.9634	1.22184
11.0941	1.219176
11.2264	1.216432
11.3603	1.213604
11.4958	1.21069
11.6329	1.207686
11.7716	1.204589
11.912	1.201396
12.0541	1.198103
12.1979	1.194705
12.3433	1.1912
12.4905	1.187582
12.6395	1.183847
12.7902	1.179991
12.9428	1.176009
13.0971	1.171895
13.2533	1.167643
13.4114	1.163249
13.5713	1.158706
13.7332	1.154007
13.897	1.149145
14.0627	1.144114
14.2304	1.138906
14.4001	1.133512
14.5719	1.127923
14.7456	1.122131
14.9215	1.116125
15.0995	1.109896
15.2795	1.103431
15.4618	1.09672
15.6462	1.089748
15.8327	1.082502
16.0216	1.074968
16.2126	1.067129
16.406	1.058969
16.6017	1.050468
16.7996	1.041607
17	1.032364

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: —

NaF (Sodium fluoride): all datasets

Li 1976: n 0.15–17 µm n 0.15–17 µm default

About NaF (Sodium fluoride)

Sodium fluoride (NaF) is a white crystalline solid that, when purified, can be processed into transparent optical components. With a broad transparency window spanning from the ultraviolet to the mid-infrared regions, NaF is particularly valuable for certain optical applications, especially in deep ultraviolet systems. However, like some other alkali halides, NaF is sensitive to moisture and can be hygroscopic, making it imperative to ensure proper handling and storage to maintain its optical qualities.

More about NaF (Sodium fluoride) →

Provenance

Version: 1 (snapshot c5c2f18)
Source page: refractiveindex.info
Original file: database/data/main/NaF/nk/Li.yml
ID: ds_be3996eeed94
API: /v1/datasets/ds_be3996eeed94

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