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Home > Products > Optics > Technical Reference and Fundamental Applications > Optical Materials

Optical Materials
Optical Materials


Product Detail Catalog PDF
Product Detail

BK 7

BK 7 is one of the most common borosilicate crown glasses used for visible and near infrared optics. Its high homogeneity, low bubble content, and straightforward manufacturability make it a good choice for transmissive optics. The transmission range for BK 7 is 380–2100 nm. It is not recommended for temperature sensitive applications, such as precision mirrors.



UV Grade Fused Silica

UV Grade Fused Silica is synthetic amorphous silicon dioxide of extremely high purity. This non-crystalline, colorless silica glass combines a very low thermal expansion coefficient with good optical qualities, and excellent transmittance in the ultraviolet. Transmission and homogeneity exceed those of crystalline quartz without the problems of orientation and temperature instability inherent in the crystalline form. Fused silica is used for both transmissive and reflective optics, especially where high laser damage threshold is required.



CaF2

Calcium Fluoride is a cubic single crystal material grown using the vacuum Stockbarger Technique with good vacuum UV to infrared transmission. CaF2 has excellent UV transmission, down to 170 nm, and its non-birefringent properties make it ideal for deep UV transmissive optics. Material for IR use is grown using naturally mined fluorite, at much lower cost. CaF2 is sensitive to thermal shock, so care must be taken during handling.



MgF2

Magnesium Fluoride is a positive birefringent crystal grown using the vacuum Stockbarger Technique with good vacuum UV to infrared transmission. It is typically oriented with the c axis parallel to the optical axis to reduce birefringent effects. High vacuum UV transmission, down to 150 nm, and its proven use in fluorine environments make it ideal for lenses, windows, and polarizers for Excimer lasers. MgF2 is resistant to thermal and mechanical shock.



Crystal Quartz

Crystal Quartz is a positive uniaxial birefringent single crystal grown using a hydrothermal process. It has good transmission from the vacuum UV to the near infrared. Due to its birefringent nature, crystal quartz is commonly used for wave plates.



Pyrex®

Pyrex® is a borosilicate glass with a low coefficient of thermal expansion. It is mainly used for non-transmissive optics, such as mirrors, due to its low homogeneity and high bubble content.

Zerodur®

Zerodur® is a glass ceramic material that has a coefficient of thermal expansion approaching zero, as well as excellent homogeneity of this coefficient throughout the entire piece. This makes Zerodur ideal for mirror substrates where extreme thermal stability is required. Zerodur should not be used for transmissive optics due to inclusions in the material.

Properties of Optical Materials
    Abbe Number
vd
 Coefficient of Thermal Expansion
(10-6/°C)
 Conductivity
(W/m°C)
 Heat Capacity
(J/gm°C)
 Density at 25°C
(gm/cm3)
 Knoop Hardness
(kg/mm2)
 Young’s Modulus
(GPa)
 BK 7  64.17  7.1  1.114  0.858  2.51  610  81.5
 SF 2  33.85  8.4  0.735  0.498  3.86  410  55
 UV Fused Silica  67.8  0.52  1.38  0.75  2.202  600  73
 CaF2  94.96  18.85  9.71  0.85  3.18  158  75.8
 MgF2  106.18  13.7 || to c axis
8.48 ^ to c axis
 21 || to c axis
30 to ^ c axis
 1.024  3.177  415  138.5
 Crystal Quartz  69.87  7.1 to || c axis
13.2 ^ to c axis
 10.4 || to c axis
6.2 ^ to c axis
 0.74  2.649  740  97 || to c axis
76.5 ^ to c axis
 Pyrex®  66  3.25  1.13  0.75  2.23  418  65.5
 Zerodur®  56.09  0 ± 0.1  1.46  0.80  2.53  620  90.3


Index of Refraction
 Wavelength
(nm)
 Source  BK 7  SF 2  UV Fused Silica  CaF2  MgF2
no
 MgF2
ne
 Crystal Quartz
no
 Crystal Quartz
ne
 193  ArF excimer laser  1.65528  1.52127  1.56077  1.50153  1.42767  1.44127  1.66091  1.67455
 244  Ar-Ion laser  1.58265  1.98102  1.51086  1.46957  1.40447  1.41735  1.60439  1.61562
 248  KrF excimer  1.57957  1.93639  1.50855  1.46803  1.40334  1.41618  1.60175  1.61289
 257  Ar-Ion laser  1.57336  1.86967  1.50383  1.46488  1.40102  1.41377  1.59637  1.60731
 266  Nd:YAG laser  1.56796  1.82737  1.49968  1.46209  1.39896  1.41164  1.59164  1.60242
 308  XeCl excimer laser  1.55006  1.73604  1.48564  1.45255  1.39188  1.40429  1.57556  1.58577
 325  HeCd laser  1.54505  1.71771  1.48164  1.44981  1.38983  1.40216  1.57097  1.58102
 337.1  N2 laser  1.54202  1.70749  1.47919  1.44813  1.38858  1.40085  1.56817  1.57812
 351  XeF excimer laser  1.53896  1.69778  1.47672  1.44642  1.38730  1.39952  1.56533  1.57518
 351.1  Ar-Ion laser  1.53894  1.69771  1.47671  1.44641  1.38729  1.39951  1.56531  1.57516
 354.7  Nd:YAG laser  1.53821  1.69548  1.47612  1.44601  1.38699  1.39920  1.56463  1.57446
 363.8  Ar-Ion laser  1.53649  1.69029  1.47472  1.44504  1.38626  1.39844  1.56302  1.57279
 404.7  Mercury arc, h line  1.53023  1.67263  1.46961  1.44151  1.38360  1.39567  1.55714  1.56670
 416  Kr-Ion laser  1.52885  1.66893  1.46847  1.44072  1.38301  1.39505  1.55583  1.56535
 435.8  Mercury arc,g line  1.52669  1.66331  1.46670  1.43949  1.38207  1.39408  1.55379  1.56323
 441.6  HeCd laser  1.52611  1.66184  1.46622  1.43916  1.38183  1.39382  1.55324  1.56266
 457.9  Ar-Ion laser  1.52461  1.65807  1.46498  1.43830  1.38118  1.39314  1.55181  1.56119
 465.8  Ar-Ion laser  1.52395  1.65641  1.46443  1.43792  1.38088  1.39284  1.55118  1.56053
 472.7  Ar-Ion laser  1.52339  1.65505  1.46397  1.43760  1.38064  1.39258  1.55065  1.55998
 476.5  Ar-Ion laser  1.52309  1.65432  1.46372  1.43744  1.38051  1.39245  1.55036  1.55969
 480  Cadmium arc, F’ line  1.52283  1.65367  1.46350  1.43728  1.38040  1.39233  1.55011  1.55943
 486.1  Hydrogen arc, F line  1.52238  1.65258  1.46313  1.43703  1.38020  1.39212  1.54968  1.55898
 488  Ar-Ion laser  1.52224  1.65225  1.46301  1.43695  1.38014  1.39206  1.54955  1.55885
 496.5  Ar-Ion laser  1.52165  1.65083  1.46252  1.43661  1.37988  1.39179  1.54898  1.55826
 501.7  Ar-Ion laser  1.52130  1.65000  1.46223  1.43641  1.37973  1.39163  1.54865  1.55792
 510.6  Cu vapor laser  1.52073  1.64865  1.46176  1.43609  1.37948  1.39137  1.54810  1.55735
 514.5  Ar-Ion laser  1.52049  1.64808  1.46156  1.43595  1.37937  1.39126  1.54787  1.55711
 532  Nd:YAG laser  1.51947  1.64570  1.46071  1.43537  1.37892  1.39079  1.54689  1.55610
 543.5  HeNe laser  1.51886  1.64427  1.46019  1.43502  1.37865  1.39051  1.54630  1.55549
 546.1  Mercury arc, e line  1.51872  1.64397  1.46008  1.43494  1.37859  1.39044  1.54617  1.55535
 578.2  Cu vaport laser  1.51720  1.64053  1.45880  1.43408  1.37792  1.38974  1.54470  1.55383
 587.6  Helium arc, d line  1.51680  1.63963  1.45846  1.43385  1.37774  1.38956  1.54431  1.55343
 589.3  Sodium arc, D line  1.51673  1.63947  1.45840  1.43381  1.37771  1.38952  1.54424  1.55336
 594.1  HeNe laser  1.51653  1.63904  1.45824  1.43370  1.37762  1.38943  1.54405  1.55316
 611.9  HeNe laser  1.51584  1.63752  1.45765  1.43331  1.37732  1.38911  1.54337  1.55247
 628  Ruby laser  1.51526  1.63626  1.45716  1.43298  1.37706  1.38884  1.54281  1.55188
 632.8  HeNe laser  1.51509  1.63590  1.45702  1.43289  1.37698  1.38876  1.54264  1.55171
 635  Laser diode  1.51501  1.63574  1.45695  1.43284  1.37695  1.38873  1.54257  1.55164
 643.8  Cadmium arc, C' line  1.51472  1.63512  1.45671  1.43268  1.37682  1.38859  1.54228  1.55134
 647.1  Kr-Ion laser  1.51461  1.63489  1.45661  1.43262  1.37677  1.38854  1.54218  1.55123
 650  Laser diode  1.51452  1.63469  1.45653  1.43257  1.37673  1.38850  1.54209  1.55114
 656.3  Hydrogen arc, C line  1.51432  1.63427  1.45637  1.43246  1.37664  1.38840  1.54189  1.55093
 670  Laser diode  1.51391  1.63340  1.45601  1.43223  1.37646  1.38821  1.54148  1.55051
 676.4  Kr-Ion laser