Optical constants

Refractive index of NaCl (Sodium chloride)

Li 1976: n 0.20–30 µm

Data
formula 1
Range
0.2–30 µm
Licence
CC0-1.0

Plot

Click the plot to set the calculator wavelength.

At one wavelength

Range 0.2–30 µm
Refractive index n
1.5442
Extinction coefficient k
0
Permittivity ε1
2.38457
Permittivity ε2
0
Absorption coefficient α
0 cm⁻¹
Penetration depth δ = λ/(2πk)
— nm
Abbe number Vd
42.888
Chromatic dispersion dn/dλ
-0.0647131 µm⁻¹
Group index ng
1.58223
Group velocity dispersion
125.393 fs²/mm
Dispersion parameter D
-684.087 ps/(nm·km)
Photon energy
2.11001 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

# NaCl (Sodium chloride): Li 1976: n 0.20–30 µm
nacl = ls.fetch_refractiveindex("main", "NaCl", "Li", ref="c5c2f188e848453def5970e347399d653df2ffc2")
print(nacl.range_nm)  # (200, 30000) nm
eps = nacl.eps([633])  # complex permittivity

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

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
n2−1=0.00055+0.198λ2λ2−0.052+0.48398λ2λ2−0.12+0.38696λ2λ2−0.1282+0.25998λ2λ2−0.1582+0.08796λ2λ2−40.52+3.17064λ2λ2−60.982+0.30038λ2λ2−120.342

Valid from 0.2 to 30.0 µm.

Coefficients as stored
CiValue
C10.00055
C20.198
C30.05
C40.48398
C50.1
C60.38696
C70.128
C80.25998
C90.158
C100.08796
C1140.5
C123.17064
C1360.98
C140.30038
C15120.34

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
NaCl (Sodium chloride), Li 1976: n 0.20–30 µm: n and k versus wavelength
λ (µm)n
0.21.789989
0.2025271.777632
0.2050871.766192
0.2076791.755562
0.2103031.745655
0.2129611.736395
0.2156521.727719
0.2183771.71957
0.2211371.711901
0.2239311.704669
0.2267611.697837
0.2296271.691373
0.2325291.685248
0.2354671.679435
0.2384431.673912
0.2414561.668658
0.2445071.663655
0.2475971.658884
0.2507261.654332
0.2538951.649983
0.2571031.645826
0.2603521.641848
0.2636421.638039
0.2669741.634389
0.2703481.63089
0.2737641.627532
0.2772241.624307
0.2807271.62121
0.2842751.618233
0.2878671.615369
0.2915051.612614
0.2951891.609962
0.2989191.607408
0.3026971.604947
0.3065221.602574
0.3103951.600287
0.3143181.59808
0.318291.59595
0.3223121.593894
0.3263851.591908
0.330511.58999
0.3346871.588137
0.3389161.586346
0.3431991.584614
0.3475361.582939
0.3519281.581318
0.3563751.57975
0.3608791.578232
0.3654391.576763
0.3700581.575341
0.3747341.573963
0.379471.572628
0.3842651.571335
0.3891211.570081
0.3940381.568866
0.3990181.567688
0.404061.566546
0.4091671.565439
0.4143371.564364
0.4195731.563322
0.4248761.562311
0.4302451.561329
0.4356821.560377
0.4411881.559452
0.4467631.558554
0.4524091.557683
0.4581261.556836
0.4639151.556014
0.4697781.555216
0.4757151.55444
0.4817261.553686
0.4878141.552954
0.4939791.552242
0.5002211.55155
0.5065421.550878
0.5129441.550224
0.5194261.549589
0.525991.548971
0.5326371.54837
0.5393681.547786
0.5461841.547218
0.5530861.546665
0.5600761.546128
0.5671531.545605
0.5743211.545096
0.5815781.544601
0.5889281.544119
0.596371.54365
0.6039071.543194
0.6115381.54275
0.6192671.542318
0.6270921.541897
0.6350171.541487
0.6430421.541089
0.6511681.5407
0.6593971.540322
0.667731.539954
0.6761681.539596
0.6847131.539246
0.6933661.538906
0.7021281.538575
0.7110011.538252
0.7199861.537938
0.7290841.537631
0.7382981.537333
0.7476281.537042
0.7570761.536758
0.7666431.536482
0.7763311.536213
0.7861421.53595
0.7960771.535694
0.8061371.535445
0.8163241.535201
0.826641.534964
0.8370871.534733
0.8476651.534507
0.8583771.534287
0.8692241.534073
0.8802091.533863
0.8913321.533659
0.9025961.53346
0.9140031.533265
0.9255531.533075
0.9372491.53289
0.9490931.532709
0.9610871.532533
0.9732331.532361
0.9855321.532192
0.9979861.532028
1.01061.531867
1.023371.53171
1.03631.531557
1.04941.531407
1.062661.531261
1.076091.531118
1.089691.530978
1.103461.530841
1.11741.530708
1.131521.530577
1.145821.530449
1.16031.530324
1.174961.530201
1.189811.530081
1.204851.529964
1.220071.529849
1.235491.529736
1.251111.529625
1.266921.529517
1.282931.529411
1.299141.529307
1.315561.529205
1.332181.529105
1.349021.529006
1.366061.52891
1.383331.528815
1.400811.528722
1.418511.52863
1.436441.52854
1.454591.528451
1.472971.528364
1.491591.528279
1.510431.528194
1.529521.528111
1.548851.528029
1.568421.527948
1.588241.527868
1.608321.527789
1.628641.527712
1.649221.527635
1.670061.527559
1.691171.527484
1.712541.527409
1.734181.527336
1.75611.527263
1.778291.527191
1.800761.527119
1.823521.527048
1.846561.526978
1.86991.526908
1.893531.526838
1.917461.526769
1.941691.5267
1.966221.526631
1.991071.526562
2.016231.526494
2.041711.526426
2.067511.526358
2.093641.52629
2.12011.526222
2.146891.526155
2.174021.526087
2.20151.526018
2.229321.52595
2.257491.525882
2.286021.525813
2.314911.525744
2.344161.525675
2.373781.525605
2.403781.525535
2.434161.525465
2.464921.525394
2.496071.525322
2.527611.52525
2.559551.525177
2.59191.525104
2.624651.525029
2.657821.524954
2.691411.524879
2.725421.524802
2.759861.524724
2.794741.524646
2.830061.524566
2.865821.524485
2.902041.524403
2.938711.52432
2.975851.524236
3.013451.52415
3.051531.524063
3.09011.523975
3.129151.523885
3.168691.523794
3.208731.523701
3.249281.523606
3.290341.52351
3.331931.523412
3.374031.523312
3.416671.523211
3.459851.523107
3.503571.523001
3.547841.522894
3.592681.522784
3.638081.522671
3.684061.522557
3.730611.52244
3.777761.522321
3.82551.522199
3.873841.522075
3.922791.521947
3.972371.521817
4.022571.521685
4.07341.521549
4.124881.52141
4.1771.521268
4.229791.521123
4.283241.520975
4.337371.520823
4.392181.520668
4.447691.520509
4.503891.520346
4.560811.52018
4.618441.520009
4.676811.519835
4.735911.519656
4.795761.519473
4.856361.519286
4.917731.519094
4.979881.518898
5.042811.518696
5.106541.51849
5.171071.518279
5.236421.518063
5.302591.517841
5.36961.517614
5.437461.517381
5.506171.517142
5.575751.516897
5.646221.516646
5.717571.516389
5.789821.516126
5.862991.515856
5.937081.515578
6.012111.515294
6.088081.515003
6.165021.514704
6.242931.514398
6.321821.514084
6.401711.513762
6.482611.513431
6.564531.513092
6.647491.512744
6.73151.512388
6.816561.512022
6.90271.511646
6.989941.511261
7.078271.510866
7.167721.51046
7.25831.510044
7.350021.509617
7.442911.509179
7.536961.508729
7.632211.508268
7.728661.507794
7.826331.507308
7.925231.506809
8.025381.506297
8.12681.505771
8.22951.505232
8.33351.504677
8.438811.504109
8.545451.503525
8.653441.502925
8.76281.502309
8.873531.501677
8.985671.501028
9.099221.500361
9.214211.499676
9.330651.498973
9.448571.49825
9.567971.497508
9.688881.496746
9.811321.495963
9.935311.495159
10.06091.494332
10.1881.493483
10.31681.492611
10.44711.491714
10.57911.490793
10.71281.489846
10.84821.488873
10.98531.487872
11.12411.486844
11.26471.485787
11.40711.484701
11.55121.483583
11.69721.482435
11.8451.481253
11.99471.480039
12.14631.478789
12.29981.477504
12.45521.476182
12.61261.474822
12.7721.473423
12.93341.471984
13.09681.470502
13.26231.468978
13.42991.467409
13.59971.465794
13.77151.464131
13.94551.462419
14.12181.460656
14.30021.458841
14.4811.456971
14.6641.455045
14.84931.453061
15.03691.451016
15.22691.448909
15.41941.446738
15.61421.444499
15.81151.442192
16.01141.439812
16.21371.437358
16.41861.434826
16.62611.432215
16.83621.42952
17.04891.426739
17.26441.423868
17.48261.420903
17.70351.417842
17.92721.41468
18.15381.411414
18.38321.408038
18.61551.404549
18.85071.400941
19.0891.39721
19.33021.39335
19.57451.389356
19.82181.385223
20.07231.380942
20.3261.376509
20.58281.371917
20.8431.367156
21.10631.362221
21.37311.357102
21.64321.35179
21.91671.346277
22.19361.340551
22.47411.334601
22.75811.328417
23.04571.321986
23.33691.315294
23.63191.308326
23.93051.301068
24.23291.293502
24.53911.28561
24.84931.277372
25.16331.268767
25.48131.259772
25.80331.25036
26.12941.240504
26.45961.230174
26.79391.219334
27.13251.207948
27.47541.195975
27.82261.183367
28.17421.170073
28.53031.156035
28.89081.141187
29.25591.125453
29.62561.108747
301.090972

Optical transmission calculator

Free-standing sample in vacuum, normal incidence
Method
Transmittance T
—
Reflectance R
—

Fresnel reflection calculator

Direction
Rp
—
Rs
—
R = (Rp+Rs)/2
—
Phase φp
—
Phase φs
—
Brewster angle θB
—
Critical angle θC
—