Materials: Zinc Selenide

Zinc Selenide (ZnSe)

ZnSe is a preferred material for lenses, windows, output couplers and beam expanders for its low absorptivity at infrared wavelengths and its visible transmission. For high-power applications, it’s critical that the material bulk absorption and internal defect structure be carefully controlled, that minimum-damage polishing technology be employed, and the highest quality optical thin-film coatings are used. The material absorption is verified by CO2 laser vacuum calorimetry. Our quality assurance department provides testing and specific optics certification on request.

ZnSe optics are routinely polished from 5 to 300 mm in diameter. Sizes in 300 mm diameter and 25 mm thick are manufactured to customer requirements.

ZnSe is non-hygroscopic and chemically stable, unless treated with strong acids. It’s safe to use in most industrial, field, and laboratory environments.

Prism-Grade Zinc Selenide

II-VI Infrared has the capability to grow prism grade ZnSe up to 2.50” thick. Prism grade ZnSe exhibits minimal refractive index variations within the material on planes perpendicular to the growth direction as well as in other directions. Index variations will test to less than 3 ppm at 0.6328 microns regardless of orientation. Prism grade ZnSe is commonly used in thermal imaging systems. Call our technical sales staff to discuss your specific requirements for material greater than 2.50” thick.

  • Refractive index variation less than 3 ppm @0.6328µm in all directions
  • Consistent optical performance independent of orientation
  • Thickness to 2.50"

Thermo-Optic Coefficient @ Various Wavelengths
dn/dT (10-5°C-1)

Wavelength

Temp °C

0.632µm

1.5µm

3.39µm

10.6µm

-180

7.6

5.4

5.0

4.9

-160

8.2

5.7

5.2

5.1

-140

8.7

6.0

5.4

5.4

-120

9.1

6.3

5.6

5.5

-100

9.4

6.5

5.8

5.7

-80

9.7

6.6

5.9

5.8

-60

10.0

6.7

6.0

5.9

-40

10.2

6.8

6.1

6.0

-20

10.3

6.9

6.1

6.0

0

10.5

7.0

6.2

6.1

20

10.6

7.0

6.2

6.1

40

10.7

7.0

6.2

6.1

60

10.8

7.1

6.3

6.1

80

10.9

7.1

6.3

6.2

100

11.0

7.2

6.3

6.2

120

11.1

7.2

6.4

6.3

140

11.3

7.3

6.4

6.3

160

11.5

7.4

6.5

6.4

180

11.8

7.6

6.6

6.6

200

12.1

7.8

6.7

6.7

oa

0.1

0.1

0.1

0.1

aStandard deviation from a third degree polynomial fit

A.Feldman et al, “Optical Materials Characterization Final Technical Report Feb. 1, 1978 - Sept. 30, 1978,” National Bureau of Standards Technical Note 933, Pages 53 and 54.

Material Properties

Optical Properties

Bulk Absorption Coefficient @ 10.6µm

<= 0.0005 cm-1

Temperature Change of Refractive Index @ 10.6µm

61 x 10-6/°C

Refractive Index Inhomogeneity @ 0.6328µm

< 3 x 10-6

Thermal Properties

Thermal Conductivity @ 20° C

0.18 W/cm/°C

Specific Heat

0.356 J/g/°C

Linear Expansion Coefficient @ 20° C

7.57 x 10-6/°C

Mechanical Properties

Young’s Modulus

67.2 GPa (9.75 x 106 psi)

Rupture Modulus

55.1 MPa (8,000 psi)

Knoop Hardness

105-120 kg/mm2

Density

5.27 g/cm3

Poisson’s Ratio

0.28


Wavelength
(µm)

Index

Wavelength
(µm)

Index

Wavelength
(µm)

Index

Wavelength
(µm)

Index

0.54

2.6754

1.8

2.4496

7.4

2.4201

13.0

2.3850

0.58

2.6312

2.2

2.4437

7.8

2.4183

13.4

2.3816

0.62

2.5994

2.6

2.4401

8.2

2.4163

13.8

2.3781

0.66

2.5755

3.0

2.4376

8.6

2.4143

14.2

2.3744

0.70

2.5568

3.4

2.4356

9.0

2.4122

14.6

2.3705

0.74

2.5418

3.8

2.4339

9.4

2.4100

15.0

2.3665

0.78

2.5295

4.2

2.4324

9.8

2.4077

15.4

2.3623

0.82

2.5193

4.6

2.4309

10.2

2.4053

15.8

2.3579

0.86

2.5107

5.0

2.4295

10.6

2.4028

16.2

2.3534

0.90

2.5034

5.4

2.4281

11.0

2.4001

16.6

2.3487

0.94

2.4971

5.8

2.4266

11.4

2.3974

17.0

2.3448

0.98

2.4916

6.2

2.4251

11.8

2.3945

17.4

2.3387

1.0

2.4892

6.6

2.4235

12.2

2.3915

17.8

2.3333

1.4

2.4609

7.0

2.4218

12.6

2.3883

18.2

2.3278