spacer spacer Go to Kaye and Laby Home spacer
spacer
spacer spacer spacer
spacer
spacer
spacer
spacer spacer

You are here:

spacer

Chapter: 2 General physics
    Section: 2.5 Radiation and optics
        SubSection: 2.5.8 Refractive index of optical materials

spacer
spacer

spacer

« Previous Subsection

Next Subsection »

Unless otherwise stated this page contains Version 1.0 content (Read more about versions)

2.5.8 Refractive index of optical materials

Spectral lines for refractometry

Refracting optical materials are specified by their refractive indices for a series of wavelengths. Those listed below were recommended by the International Commission for Optics in 1962 (Optica Acta, 1963, 10, 217), and are quoted to the nearest 0.1 nm for standard air. The source element and the designating letter used for some wavelengths (mainly in the visible spectral region) are shown. A number of other spectral lines at which refractive indices have been frequently quoted is also given, including some commonly used laser wavelengths.

Gas discharge lamps are available as sources over a wide range of wavelengths, and in some instances the spectra of two or three elements may be combined in one lamp. Interference filters give the most complete suppression of unwanted lines.


Source

Wavelength

nm

Designating letter

Source

Wavelength

nm

Designating letter

   

ICO 1962

Other commonly used lines

Recommended standard lines

 

 

 

 

 

 

    Zn

213.9

 

Hg

365.0

  

 i

    Hg

237.8

 

Hg

365.5

 

    Hg

269.9

 

H  

434.0

  

    Hg

289.4

 

H  

486.1

    

F

    Hg

296.7

 

Hg

577.0

 

    Hg

334.2

 

Hg

579.0

 

D

C

    Hg

366.3

 

Na

589.0

    Hg

404.7

h

Na

589.6

    Hg

435.8

g

H  

656.3

 

    Cd

467.8

 

K  

766.5

 

    Cd

508.6

 

K  

769.9

 

    Hg

546.1

e

Hg

1357.0  

 

    He

587.6

d

Hg

1367.3  

 

    Cd

643.8

C′

Common laser wavelengths

    He

667.8

 

    He

706.5

r

    Rb

780.0

 

Ar

488.0

 

    Cs

852.1

s

Ar

514.5

 

    Cs

894.4

 

He–Ne

543.4

 

    Hg

1014.0  

t

Kr

568.2

 

    Hg

1128.7  

 

He–Ne

593.9

 

    Hg

1395.1  

 

He–Ne

611.8

 

    Hg

1529.5  

 

He–Ne

632.8

 

    Hg

1813.1 

 

Kr

647.0

 

    Hg

1970.1 

 

Ruby

694.3

 

    He

2058.1 

 

 

 

 

    Hg

2325.4  

 

 

 

 

    Hg

239.9

 

Nd

1.06

 

    Hg

275.3

 

Nd-YAG

  1.065

 

    Hg

292.5

 

He–Ne

1.52

 

    Hg

390.6

 

He–Ne

3.39

 

    Cd

480.0

CO2

10.6    

 

    Rb

794.7        

 

 

 

 

 

 




Refractive indices of optical glasses

Optical glasses are available in a wide range of refractive indices and dispersions. Data are usually given in the following way:

            

 

Refractive index for the helium d line (587.6 nm),

     nd

 

               and for the mercury e line (546.1 nm),

    ne


 

Mean dispersion between the hydrogen F line (486.1 nm) and C line (656.3 nm), 

     nFnC

 

        and between the cadmium F' line (480.0 nm) and C' line (643.8 nm),

     nF'nC'


 

Reciprocal dispersive power (or constringence),

     Vd  =  (nd − l)/(nFnC)

 

        and 

     Ve  =  (ne − 1)/(nF'nC')

                        

Refractive indices are generally quoted for a number of wavelengths. Partial dispersions, for example (ndnC) or (nend), and relative partial dispersions, for example (nend)/(nFnC) or (nend)/(nF'nC'), may also be stated.

A six-figure reference number for each glass is obtained from the first three significant figures of the term (nd − 1) and the first three significant figures of Vd. For example, BSC 517642 is a borosilicate crown glass with nd = 1.51680 and Vd  =  64.17. Glasses with nd less than 1.6 and Vd greater than 55, and with nd greater than 1.6 and Vd greater than 50, are described as crowns and the remainder as flints.

Some data from a selection of optical glasses manufactured by Pilkington Special Glass Limited are given in the table for borosilicate crown, hard crown, dense barium crown, zinc crown, borate flint, light flint, dense flint, low density flint, double extra dense flint, lanthana crown and lanthana flint glasses. The refractive indices are quoted at a temperature of 20 °C and at standard atmospheric pressure (101 325 Pa).




Optical glasses

Some data for Pilkington Special Glass Limited optical glasses
(For compelete range of optical glasses see Pilkington Special Glass Limited catalogue)

Refractive index

nd

nFnC

Vd

ne

nn

Ve

ni

nh

ng

n

nC

ns

nt

Wavelength

nm

587.56

486.13−
656.28

 

546.07

479.99−
643.85

 

365.02

404.66

435.84

479.99

656.28

852.11

1014.00

 

 

 

 

 

 

 

 

 

 

 

 

 

 

BSC 517642

1.516 80

0.008 054

64.17

1.518 72

0.008 110

63.96

1.536 26

1.530 24

1.526 68

1.522 83

1.514 32

1.509 82

1.507 34

HC 524592

1.524 00

0.008 850

59.21

1.526 11

0.008 925

58.95

1.545 77

1.538 96

1.534 96

1.530 66

1.521 30

1.516 53

1.514 03

DBC 589613

1.589 13

0.009 615

61.27

1.591 42

0.009 691

61.03

1.612 65

1.605 32

1.601 01

1.596 35

1.586 19

1.580 91

1.587 07

DBC 620603

1.620 41

0.010 284

60.33

1.622 86

0.010 368

60.08

1.645 60

1.637 74

1.633 13

1.628 14

1.617 27

1.611 70

1.608 76

ZC 508612

1.508 47

0.008 310

61.19

1.510 45

0.008 380

60.92

1.528 68

1.522 39

1.518 70

1.514 71

1.505 92

1.501 30

1.498 77

LAC 697564

1.696 73

0.012 349

56.42

1.699 68

0.012 448

56.21

1.727 09

1.717 59

1.712 02

1.706 03

1.692 97

1.686 28

1.682 71

Bor F 613443

1.613 40

0.013 848

44.30

1.616 09

0.013 998

44.06

1.649 04

1.637 44

1.630 85

1.623 90

1.609 24

1.601 97

1.598 22

LF 579411

1.578 60

0.014 070

41.12

1.581 94

0.014 249

40.84

1.615 95

1.603 55

1.596 60

1.589 34

1.574 44

1.567 49

1.564 19

DF 620364

1.620 04

0.017 050

36.37

1.642 08

0.017 283

36.11

1.666 28

1.650 64

1.642 02

1.633 10

1.615 03

1.606 74

1.602 83

LDF 706303

1.705 85

0.023 295

30.30

1.711 35

0.023 662

30.06

1.772 11

1.748 83

1.736 37

1.723 80

1.699 09

1.687 98

1.682 81

DEDF 755276

1.755 20

0.027 383

27.58

1.761 67

0.027 829

27.37

1.833 36

1.805 89

1.791 21

1.776 36

1.747 30

1.734 57

1.728 89

LAF 744447

1.744 00

0.016 638

44.72

1.747 96

0.016 828

44.45

1.786 97

1.772 97

1.765 01

1.756 63

1.739 02

1.730 47

1.726 18

 

 

 

 

 

 

 

 

 

 

 

 

 

 




Optical plastics

Refractive index, n, and reciprocal dispersive power, V, are given for four commonly used optical plastics. The data have been gathered from a variety of sources, including the manufacturer, and are subject to change as more information is generated.

Refractive index
Wavelength
/nm

nF
486.1

nD
589.3

nC
656.3

 

 

 

 

 

Methyl methacrylate (acrylic)

1.498

1.492

1.489

57.2

Polystyrene (styrene)

1.604

1.590

1.585

30.8

Polycarbonate

1.598

1.584

1.578

30.1

Methyl methacrylate styrene copolymer (NAS)

1.574

1.563

1.558

33.5

 

 

 

 

 




Refractive indices of optical cements

Refractive index, nD20, for the wavelength 589.3 nm (mean of sodium D lines) at a temperature of 20 °C is given for a number of well-tried polymerized cements (Optica Acta, 1967, 14, 401). With the increasing availability of new resins for optical purposes, inspection of manufacturer’s data is recommended to determine the most appropriate cement for a specific application.

Cement

n

20

D

Cement

n

20

D

 

 

 

 

Solid Canada balsam     .    .    .    .    .    .

1.54

  Beetle 8128   .    .    .    .

1.55

Soft Canada balsam       .    .    .    .    .    .

1.53

  BS No. 8     .    .    .    .    .    .

  1.59

Cellulose caprate      .    .    .    .    .    .    .

1.47

  Epikote 817

c.1.57

Cellulose caprate (plasticized)  .    .    .    .

1.49

  Crystic 191 LV

   1.56

H.T      .    .    .    .    .    .    .    .    .    .    .

1.45

  Loctite 357 (UV curing)

   1.47

 

 

 

 




Refractive indices of calcite (Iceland Spar)

(From 200 nm to 706 nm at 18 °C, and from 801 nm to 3324 nm at 20 °C)

Wavelength

nm

Refractive index

Wavelength

nm

Refractive index

O-ray

E-ray

O-ray

E-ray

 

 

 

 

 

 

200

1.902 84

1.576 49

1422

1.635 90

 

303

1.719 59

1.513 65

1497

1.634 57

1.477 44

410

1.680 14

1.496 40

1609

1.632 61

 

508

1.665 27

1.489 56

1682

1.631 27

 

643

1.655 04

1.484 90

1749

 

1.476 38

706

1.652 07

1.483 53

1761

1.629 74

 

801

1.648 69

1.482 16

1849

1.628 00

 

905

1.645 78

1.480 98

1909

 

1.475 73

1042  

1.642 76

1.479 85

1946

1.626 02

 

1159  

1.640 51

1.479 10

2053

1.623 72

 

1229  

1.639 26

1.478 70

2100

 

1.474 92

1307  

1.637 89

1.478 31

2172

1.620 99

 

1396  

1.636 37

1.477 89

3324

 

1.473 92

 

 

 

 

 

 




Refractive indices of crystal quartz at 20 °C

Wavelength

nm

Refractive index

Wavelength

nm

Refractive index

O-ray

E-ray

O-ray

E-ray

 

 

 

 

 

 

185

1.675 78

1.689 88

1541.4

1.527 81

1.536 30

198

1.650 87

1.663 94

1681.5

1.525 83

1.534 22

231

1.613 95

1.625 55

1761.4

1.524 68

1.533 01

340

1.567 47

1.577 37

1945.7

1.521 84

1.530 04

394

1.558 46

1.568 05

2053.1

1.520 05

1.528 23

434

1.553 96

1.563 39

2300   

1.515 61

 

508

1.548 22

1.557 46

2600   

1.509 86

 

  589.3

1.544.24

1.553 35

3000   

1.499 53

 

768 

1.539 03

1.547 94

3500   

1.484 51

 

  832.5

1.537 73

1.546 61

4000   

1.466 17

 

  991.4

1.535 14

1.543 92

4200   

1.456 9  

 

1159.2

1.532 83

1.541 52

5000   

1.417     

 

1307.0

1.530 90

1.539 51

6450   

1.274     

 

1395.8

1.529 77

1.538 32

7000   

1.167     

 

1479.2

1.528 65

1.537 16

 

 

 

 

 

 

 

 

 




Refractive indices of synthetic materials at 20 °C

 

Refractive index

Wavelength

nm

Synthetic
fused
silica

Calcium
fluoride

Lithium
fluoride

 

 

 

 

213.86

1.534 30

1.484 96

1.432 29

237.83

1.514 72

1.472 15

1.422 56

239.94

1.513 36

1.471 25

1.421 86

269.89

1.498 04

1.460 98

1.413 93

275.28

1.495 91

1.459 54

1.412 80

289.36

1.490 99

1.456 20

1.410 18

292.54

1.489 99

1.455 52

1.409 65

296.73

1.488 73

1.454 67

1.408 97

334.15

1.479 77

1.448 52

1.404 10

366.33

1.474 35

1.444 79

1.401 11

404.66

1.469 62

1.441 52

1.398 47

435.84

1.466 69

1.439 50

1.396 83

467.82

1.464 29

1.437 85

1.395 47

479.99

1.463 50

1.437 31

1.395 02

486.13

1.463 12

1.437 05

1.394 80

508.58

1.461 86

1.436 18

1.394 08

546.07

1.460 08

1.434 97

1.393 05

587.56

1.458 46

1.433 89

1.392 11

632.80

1.457 02

 

1.391 26

643.85

1.456 70

1.432 72

1.391 07

769.90

1.453 86

1.430 91

1.389 35

780.02

1.453 67

1.430 79

1.389 24

794.76

1.453 41

1.430 63

1.389 07

852.11

1.452 47

1.430 07

1.388 49

894.35

1.451 84

1.429 71

1.388 09

1014.0   

1.450 24

1.428 84

1.387 07

1060.0   

1.449 68

 

1.386 70

1128.7   

1.448 87

1.428 15

1.386 17

1395.1   

1.445 83

1.426 80

1.384 10

1529.5   

1.444 27

1.426 17

1.383 02

1813.1   

1.440 71

1.424 83

1.380 56

1970.1   

1.438 53

1.424 06

1.379 09

2058.1   

1.437 23

1.423 61

1.378 22

2325.4   

1.432 93

1.422 16

1.375 30

2800.0   

 

1.419 23

1.369 37

3400.0

 

1.414 87

1.360 32

4000.0

 

1.409 63

1.349 37

4600.0

 

1.403 57

1.336 40

5000.0

 

1.399 08

1.326 56

5600.0

 

 

1.309 88

5893.2   

 

1.387 12

 

6000.0   

 

 

1.297 40

7071.8   

 

1.368 05

 

8250.0   

 

1.344 40

 

9429.1   

 

1.316 05

 

 

 

 

 




Refractive indices and useful transmission ranges of other optical materials

Values at or near a temperature of 20 °C.

Infrared materials

Wavelength

μm

Refractive
index

Transmission range

μm

 

 

 

 

Arsenic trisulphide   .   .   .   .   .

1.00             

2.4777

0.6 to 13

 

10.00             

2.3816

 

Barium fluoride   .   .   .   .   .   .

0.546           

1.4759

0.15 to 12.5

 

10.346           

1.3964

 

Cadmium telluride   .   .   .   .   .

1.00             

2.838  

0.9 to ~ 16

     (Irtran 6)

10.00             

2.672  

 

Caesium bromide   .   .   .   .   .

1.0               

1.6779

0.22 to 55

 

39.0               

1.5624

 

Caesium iodide     .   .   .   .   .

1.00             

1.7572

0.25 to 55

 

50.0               

1.6366

 

Diamond    .   .   .   .   .    .   .

0.546           

2.4235

~ 0.25 to > 80

Gallium arsenide  .   .   .   .   .

10.0               

3.135  

1 to ~ 15

Germanium     .   .   .   .   .   .

10.00             

4.0032

1.8 to 23

Lead fluoride   .   .   .   .   .  .

0.55             

1.7722

0.25 to ~ 16

 

10.00             

1.6367

 

Magnesium oxide   .   .   .   .

 1.00             

1.7227

0.3 to 7

     (Irtran 5)

 8.00             

1.4824

 

Potassium bromide    .   .   .

0.546           

1.5639

0.23 to 25

 

21.18             

1.4866

 

Potassium chloride    .   .   .

0.546           

1.4932

0.21 to 20

 

20.4               

1.389  

 

Potassium iodide      .   .   .

0.546           

1.6731

~ 0.25 to ~ 45

 

20                  

1.5964

 

Silicon     .   .   .   .   .   .   .

10.00             

3.4170

1.2 to 10

Silver chloride     .   .   .   . 

1.0               

2.0224

0.4 to 30

 

20.0               

1.9069

 

Sodium chloride     .   .   .

0.50             

1.5516

0.2 to 20

 

20.0               

1.3822

 

Sodium fluoride .   .   .    .   .   .

0.546           

1.3264

0.15 to 14

 

10.3               

1.233  

 

Strontium titanate .   .   .    .   .   .

0.56             

2.4254

0.39 to 6.8

 

5.00             

2.1221

 

Thallium bromo-iodide .   .   .    .

0.54             

2.6806

0.6 to 40

     (KRS 5)

30.0               

2.2887

 

Zinc selenide .   .   .    .   .   .

1.00             

2.485  

0.45 to ~ 21.5

     (Irtran 4)

15.00             

2.370  

 

Zinc sulphide .   .   .    .   .   .

1.00             

2.2907

1.0 to 14.5

    (Irtran 2)

12.00             

2.1688

 

Zinc sulphide .   .   .    .   .   .

0.546            

2.3884

0.37 to 14

     (Cleartran)

12.00             

2.1710

 

 

 

 

 

For some useful data see Chrystran Limited Optical Crystals Handbook.




Birefringent materials

Wavelength

μm

Refractive index

Transmission
range
/μm

O-ray

E-ray

 

 

 

 

 

Ammonium dihydrogen phosphate   .   .   .   .

0.546

1.5266

1.4808

0.13 to ~ 1.7

    (ADP)

1.014

1.5084

1.4690

 

Potassium dihydrogen phosphate    .   .   .   .

0.546

1.5115

1.4698

0.25 to ~ 1.7

    (KDP)

1.014

1.4954

1.4604

 

Magnesium fluoride   .   .   .   .   .   .   .   .

0.546

1.3786

1.3904

0.11 to 7.5

 

1.083

1.3731

1.3846

 

Rutile   .   .   .   .   .   .   .   .   .   .   .   .   .

0.546

2.652  

2.958  

~ 0.43 to 6.2

    (Titanium dioxide)

1.014

2.484  

2.747  

 

Sapphire   .   .   .   .   .   .   .   .   .   .   .   .

0.546

1.7708

0.15 to 5.5

    (Aluminium oxide)

1.014

1.7555

1.7479

 

 

 

 

 

 




Refractive indices of liquids

Suitable media for refractometry.
Refractive index for the wavelength 589.3 nm (mean of sodium D lines) and temperature of 20 °C or close to 20 °C.

Liquid

Refractive index

 

 

Water   .   .   .   .   .   .   .   .   .   .    .   .

1.333

Paraldehyde   .   .   .   .   .   .   .   .   .   .

1.405

Carbon tetrachloride   .   .   .   .   .   .   .

1.46  

Glycerol     .   .   .   .   .   .   .   .   .   .   .

1.47  

Liquid paraffin .   .   .   .   .   .   .   .   .   .

1.48  

Toluene   .   .   .   .   .   .   .   .   .   .   .   .

1.497

Benzene   .   .   .   .   .   .   .   .   .   .   .   .

1.501

Ethyl salicylate   .   .   .   .   .   .   .   .   .   .  

1.523

Chlorobenzene   .   .   .   .   .   .   .   .   .   . 

1.525

Methyl salicylate  .   .   .   .   .   .   .   .   .   . 

1.538

Ethyl cinnamate      .   .   .   .   .   .   .   .   .

1.559

Benzyl benzoate     .   .   .   .   .   .   .   .   .

1.568

Aniline       .   .   .   .   .   .   .   .   .   .   .   .

1.586

Quinoline       .   .   .   .   .   .   .   .   .   .   .

1.627

α-Monobromonaphthalene     .   .   .   .   .

1.660

Methylene iodide   .   .   .   .   .   .   .   .   . 

1.737

Methylene iodide and sulphur (saturated)  

1.78  

Oil, paraffin   .   .   .   .   .   .   .   .   .   .   .

1.44 

Oil, olive   .   .   .   .   .   .   .   .   .   .   .   .

1.46 

Oil, turpentine   .   .   .   .   .   .   .   .   .   . 

1.47 

Oil, cedar     .   .   .   .   .   .   .   .   .   .   . 

1.516

Oil, cloves   .   .   .   .   .   .   .   .   .   .   . 

1.532

Oil, cinnamon   .   .   .   .   .   .   .   .   .   .

1.601

 

 




Calibration of liquid refractometers

Liquid of known refractive index, n, may be used to calibrate critical angle and Vee-block refractometers throughout the visible spectral region, and over a small range of ambient temperatures using the temperature coefficient of refractive index, dn/dt.

Wavelength

nm

Distilled water

n20 °C

dn/dt per °C
(20 °C–25 °C)

 

 

 

404.66

1.342 742

− 0.000 101

435.84

1.340 210

− 0.000 100

486.13

1.337 123

− 0.000 099

546.07

1.334 466

− 0.000 098

587.56

1.333 041

− 0.000 097

589.30

1.332 988

− 0.000 097

632.80

1.331 745

− 0.000 096

656.28

1.331 151

− 0.000 096

706.52

1.330 020

− 0.000 095

 

 

 




Light transmission, Pilkington Special Glass Limited optical glass

Internal transmittance, T25, is defined as the ratio of radiant flux reaching the exit surface of a plane parallel plate of glass 25 mm thick to the flux which leaves the entry surface.

Glass
type

BSC
517642

HC
524592

DBC
589613

ZC
508612

LAC
697564

LF
579411

LDF
706303

DEDF
755276

LAF
744447

Wavelength

nm

Internal transmittance, T25

 

 

 

 

 

 

 

 

 

 

360

0.901

0.918

0.715

0.787

0.629

0.816

0.109

0.271

380

0.962

0.939

0.898

0.894

0.844

0.908

0.342

0.508

0.631

400

0.981

0.977

0.963

0.965

0.937

0.969

0.768

0.785

0.838

420

0.982

0.982

0.980

0.975

0.972

0.974

0.886

0.907

0.931

440

0.983

0.980

0.983

0.980

0.983

0.973

0.922

0.955

0.964

460

0.987

0.981

0.985

0.989

0.989

0.978

0.939

0.975

0.978

500

0.992

0.990

0.991

0.995

0.994

0.984

0.966

0.989

0.990

 

 

 

 

 

 

 

 

 

 

In the wavelength range 500 nm to 1000 nm, T25 0.970 for the glasses shown in the Table. Data taken from Pilkington Special Glass Limited catalogue.




References

W. G. Driscoll (ed.) (1978) Handbook of the Optical Society of America, McGraw-Hill Book Co, Chapter 7.
D. E. Gray (ed.) (1972) Handbook of the American Institute of Physics, McGraw-Hill Book Co, Section 6.
E. D. Palik (ed.) (1985) Handbook of Optical Constants of Solids, Academic Press, London.
E. D. Palik (ed.) (1991) Handbook of Optical Constants of Solids II, Academic Press, London.

M.Debenham

« Previous Subsection

Next Subsection »

spacer


spacer
spacer
spacer spacer spacer

Home | About | Table of Contents | Advanced Search | Copyright | Feedback | Privacy | ^ Top of Page ^

spacer

This site is hosted and maintained by the National Physical Laboratory © 2014.

spacer