Click on the bars in the graph above to view the transmission plot for each optical material.

Thorlabs offers a wide variety of optical substrates that are ideal for use in various applications. The graph to the right compares the transmission ranges of some of the most common substrates we offer. This page details optical properties for these substrates, as well as the substrates used in our aspheric and achromatic lenses. To quickly navigate through these substrates, use the Table of Contents listed below or click on the tabs above.

For more information about the properties listed throughout this page, please see the Tutorial tab above. If you have questions about a substrate not described on this page, please contact Tech Support.

Table of Contents

This tab details the key crystalline, optical, physical, and thermal properties provided for the substrates featured on the rest of the tabs on this page. Please contact Tech Support if you have any further questions concerning these properties.

Table of Contents

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Click Here for N-BK7's Sellmeier Equation

Optical Properties

Index of Refraction
Index of refraction, n, is an optical property that describes how light propagates through a material. It is defined as

where c is the speed of light in a vacuum, and v is the speed of light through the material. The index of refraction of a material varies with both temperature and wavelength. The change of index of refraction with temperature is discussed in more detail in the Thermal Properties section below. The change in index of refraction with wavelength is known as dispersion and can be clearly seen in the graph to the right, which shows the variation in n for N-BK7.

Attenuation Coefficient
The attenuation coefficient, α, is a material property that characterizes the degree of transparency of a medium. The intensity transmitted through a material is described by the Beer-Lambert law:

where I is the transmitted intensity, I₀ is the incident intensity, and l is the thickness of the material. Losses described by the attenuation coefficient include both scattering and absorption by the material. Like index of refraction, the attenuation coefficient of a material varies with wavelength. 

Sellmeier Equation
The Sellmeier equation is used to characterize the dispersion of light with respect to wavelength and is written in the form

where λ is wavelength in μm and B₁ , B₂ , B₃ , C₁ , C₂ , and C₃ are constants unique to the material being tested. The Sellmeier equation used to plot N-BK7's index of refraction as a function of wavelength can be seen by clicking on the hyperlink in the footnote under the graph.

Abbe Number
Also known as the V-number, the Abbe number is an optical property that quantifies a material's dispersion, or variation in refractive index with respect to wavelength. It is defined by the equation

where V_d is the Abbe number, and n_d , n_F , and n_C  are the refractive indexes of the material at 587.6 nm, 486.1 nm, and 656.3 nm, respectively. A high Abbe number is indicative of low dispersion whereas a low Abbe number indicates high dispersion.

Fresnel Reflectance and Transmittance
The Fresnel equations describe the reflection and transmission of light at an interface between two materials with different indices of refraction. These equations provide reflectance and transmittance values, which give the ratio of the reflected and transmitted light intensity, respectively, to the incident intensity. This can be written as

where R is the reflectance, T is the transmittance, I₀ is the incident intensity, I_r is the reflected intensity, and I_t is the transmitted intensity. The Fresnel values given on this page are for normal incidence.

Physical Properties

Knoop Hardness
Knoop hardness (HK) is a measure of a material's mechanical hardness and is most commonly given for brittle materials. Knoop hardness is tested by pressing a pyramidal diamond-shaped indenter into a material sample and analyzing the resulting indentation in the material. The process is shown in the animation denoted as Figure 1 to the right. The Knoop Hardness is then calculated using

where HK is the Knoop hardness, K is a constant related to the indenter's geometry, P is the test load, and L is the longest diagonal length of the diamond-shaped indentation.

Moduli: Young, Shear, and Bulk
Young's modulus, shear modulus, and bulk modulus are all measures of how a material deforms, or strains, under different stresses. Stress is the term used to describe the amount of force applied to a sectional area of a sample. Stress is mathematically calculated using the following equation:

where σ is stress and F is the force applied on the cross-sectional area, A, of a sample. The term strain is used to describe the deformation of a sample as a result of a stress and is mathematically calculated using

where ε is strain, Δx is the change in size of a sample, and x is the original size of a sample.

Young's modulus, shear modulus, and bulk modulus are useful in quantifying the stiffness of materials. A stiffer material has higher moduli than a more flexible material.

Young's Modulus
Young's modulus (E ), also known as elastic modulus, describes how a material deforms under a normal, or tensile, stress. To measure Young's modulus, a material is either pulled or compressed along its length, and the resulting change in length is measured. The animation in Figure 2 demonstrates one method of measuring Young's modulus. Mathematically, Young's modulus is calculated by dividing a sample's normal stress over its normal strain. In Figure 2 and in the equation below, E is Young's modulus, L is the original length of the sample, ΔL is the change in the length of the sample, and F is the force applied normal to the face of the sample with surface area, A.

Shear Modulus
Shear modulus (G ) is the measure of how a sample deforms when it is sheared (i.e., when a force is applied parallel to one surface of the sample and an opposing force is applied to the opposite face, as shown in Figure 3). Mathematically, shear modulus is calculated by dividing a sample's shear stress by its shear strain. Shear stress and strain are demonstrated in the Figure 3 animation. Within the animation and in the following equation, G is the shear modulus, h is the height of the test sample, Δx is the change in shape due to the shear force, F , applied to the sample, and A is the surface area of the face to which the force is applied.

Bulk Modulus
Bulk modulus (K ) describes a material's volumetric stiffness when exposed to increased uniform pressure. When a material is exposed to high, uniform, external pressure, it tends to shrink. Bulk modulus is the measure of how much a material resists this shrinking. Mathematically, bulk modulus is calculated by dividing a sample's bulk stress by its bulk strain. In the Figure 4 animation and the equation below, K is the bulk modulus, V represents the original volume of the sample, and V′ is the volume of a sample after it is exposed to change in uniform pressure, ΔP.

Poisson's Ratio
Poisson's ratio, ν (nu), is a measure of how much a material contracts in the perpendicular direction due to stretching, or conversely, how much a material expands in the direction perpendicular to the applied force due to its compression. Imagine stretching a rubber band and watching the band become thinner; as you continue to stretch it farther, the thinness also increases. Poisson's ratio can also be measured by compressing a material and measuring how much thicker it gets, as shown in the Figure 5 animation. Mathematically, Poisson's ratio is defined as the negative change in transverse strain divided by the change in axial strain. In Figure 5 and the equation below, ε_trans is transverse strain (i.e., the strain perpendicular to the applied force, F) and ε_axial is axial strain (i.e., the strain parallel to the applied force). dε_axial and dε_trans are the changes in strain on the sample due to an applied force.

Relationship between Poisson's Ratio and the Young's, Shear, and Bulk Moduli
In isotropic materials, there is a linear relationship between Poisson's ratio, Young's modulus, shear modulus, and bulk modulus. This makes it possible to calculate any unknown moduli of certain materials using only two known values. Isotropic materials have identical physical properties in every orientation. In other words, their properties do not vary as the axis along which the force is applied varies. Many optical glasses, such as N-BK7 or N-SF11, are isotropic and thus have moduli values calculated from the equations

where E is Young's modulus, G is shear modulus, K is bulk modulus, and ν is Poisson's ratio. These relationships are not true for anisotropic materials. Most crystalline materials, such as Thorlabs' fluoride optics, are anisotropic, and hence, each modulus must be measured separately. Moduli that were calculated rather than measured are noted in the specification table for every applicable substrate.

Thermal Properties

Coefficient of Thermal Expansion
The coefficient of thermal expansion (CTE) describes a material’s tendency to expand or contract with a change in temperature. A positive CTE would describe a material that expands with increases in temperature, and a negative CTE describes a material that contracts with increases in temperature. Specifically, the coefficient of linear thermal expansion (a_L ) is the numerical description of how much the length of a material changes with temperature and can be expressed as

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where a_L is the coefficient of linear thermal expansion, L is the original length of the sample, dL is the change in length of the sample, and dT is the change in temperature.

Change in Index of Refraction with Temperature
The index of refraction of a material is not only dependent on the wavelength of light passing through it; it is also dependent on the temperature, as shown in the graph to the right. This change in index of refraction with temperature is also known as the thermo-optic coefficient and is commonly written as dn/dT. Because the thermo-optic coefficient varies both with temperature range and wavelength, a standard temperature range and test wavelength are selected when reporting this specification for a material.

Crystalline Properties

Parallel versus Perpendicular
Crystalline material data is often given for both the parallel and perpendicular axes of the crystal to ensure accuracy. The crystalline structure of some materials results in a difference between the properties along the optical axis and those along the perpendicular axis. The parallel, or extraordinary, axis is the axis along which transmitted light will suffer no birefringence. It is parallel to the optical axis of the crystal. The perpendicular, or ordinary, axis is perpendicular to the optical axis.

Alpha-BBO Specifications
Index of Refractiona
Index of Refraction at d-Line (587.6 nm)a	ne = 1.533 no = 1.673
Sellmeier Equation, Extraordinarya
Sellmeier Equation, Ordinarya
Abbe Number (Vd), Extraordinary	56.18
Abbe Number (Vd), Ordinary	52.23
Transmission Range	190 nm - 3.5 µm
Fresnel Reflectance and Transmittance, Extraordinary (Calculated)
Fresnel Reflectance and Transmittance, Ordinary (Calculated)
Density	3.85 g/cm3
Knoop Hardness	-
Young's Modulus	39 GPa
Shear Modulus	12.3 GPa
Bulk Modulusb	-
Poisson's Ratio	0.58
Coefficient of Thermal Expansion	36 x 10-6 /°C (Parallel) 4 x 10-6 /°C (Perpendicular)
Heat Capacity	0.49 J/(g*K)
Melting Point	1095°C
Change in Index of Refraction with Temperature	-9.3 x 10-6 /°C (Parallel) -16.6 x 10-6 /°C (Perpendicular)

Alpha-BBO Optics Selection

Glan-Laser Polarizers	AR-Coated
Wollaston Prisms	Uncoated

• Appel, R., Dyer, C. D., & Lockwood, J. N. (2002). Design of a broadband UV–visible alpha-barium borate polarizer. Applied Optics, 41(13), 2474.
• Value cannot be calculated because α-BBO is an anisotropic material. For more information, please see the Tutorial tab.

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This data was gathered through a GLB5 Glan-Laser Polarizer of thickness
8.2 mm and is indicitive of the material's properties..

Alpha-BBO (α-BBO, α-BaB₂O₄) is a negative uniaxial crystal, which is the high temperature form of β-BBO, and exhibits many of the same physical and optical properties. Alpha-BBO’s high birefringent structure makes it a useful substrate in the fabrication of polarization optics. Since α-BBO is a soft crystal that is easily damaged, all of our α-BBO polarizers are offered in metal housings. With convenient threadings and adapters, these housings can easily be mounted into our optomechanical products. Alpha-BBO has a transmission range from 190 nm to 3.5 µm. It has an ordinary refractive index of 1.673 and an extraordinary refractive index of 1.533 at 587.6 nm.

Click on the images below or open the table to the right to see Thorlabs’ complete selection of optics made from α-BBO.

Barium Fluoride Specifications
Index of Refractiona
Index of Refraction at Nd:YAG (1.064 µm)a	1.468
Sellmeier Equationa
Abbe Number (Vd)	81.78
Transmission Range	200 nm - 11 µm
Fresnel Reflectance and Transmittance (Calculated)
Density	4.893 g/cm3
Knoop Hardness	82 kg/mm2
Young's Modulus	53.07 GPa
Shear Modulus	25.4 GPa
Bulk Modulus	56.4 GPa
Poisson's Ratio	0.343
Coefficient of Thermal Expansion	18.4 x 10-6 /°C
Heat Capacity	0.41 J/(g*K)
Melting Point	1368 °C
Change in Index of Refraction with Temperature (+20/+40°C @ 1060 nm)	-15.2 x 10-6 /°C

Barium Fluoride Optics Selection

Spherical Lenses	Plano-Convex	E-Coated (2 - 5 µm)
Windows	Flat	E-Coated (3 - 5 µm)
	Wedged	Uncoated
Polarizers	Wire Grid	Holographic

• H. H. Li. Refractive Index of Alkaline Earth Halides and its Wavelength and Temperature Derivatives. J. Phys. Chem. Ref. Data 9, 161-289 (1980)

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Barium Fluoride (BaF₂) is transparent from the UV to the IR (200 nm - 11 µm) and has an index of refraction of 1.468 at 1.064 µm. Barium fluoride's properties are similar to those of calcium fluoride, but it is more resistant to high-energy radiation. It is, however, less resistant to water damage. Pronounced degradation of the BaF₂ substrate occurs at 500 °C when exposed to water, but in dry environments, it can be used in applications requiring exposure to temperatures up to 800 °C.

When handling optics, one should always wear gloves. This is especially true when working with barium fluoride as it is a hazardous material. For your safety, please wear gloves whenever handling BaF₂ and thoroughly wash your hands afterwards. Click here to download a pdf of the MSDS for BaF₂.

Click on the images below or open the table to the right to see Thorlabs’ complete selection of optics made from BaF₂.

Calcite Specifications
Index of Refractiona
Index of Refraction at Nd:Yag (1.064 µm)a	ne =  1.480 no = 1.642
Sellmeier Equation, Extraordinarya
Sellmeier Equation, Ordinarya
Abbe Number (Vd), Extraordinary	79.17
Abbe Number (Vd), Oridinary	49.91
Transmission Rangeb	300 nm - 2.3 μm
Fresnel Reflectance and Transmittance, Extraordinary (Calculated)
Fresnel Reflectance and Transmittance, Ordinary (Calculated)
Density	2.71 g/cm3
Knoop Hardness	155 kg/mm2
Young's Modulus	88.19 GPa (Parallel) 72.35 GPa (Perpendicular)
Shear Modulus	35 GPa
Bulk Modulus	129.53 GPa
Poisson's Ratio	0.85
Coefficient of Thermal Expansion (@ 0°C)	25 x 10-6 /°C (Parallel) 5.8 x 10-6 /°C (Perpendicular)
Heat Capacity	0.852 J/(g*K)
Melting Point	825°C
Change in Index of Refraction with Temperature (@ 500 nm)	3 x 10-6 /°C (Parallel) 13 x 10-6 /°C (Perpendicular)

Calcite Optics Selection

Polarizers	Beam Displacers	Mounted
	Glan-Laser	Uncoated / AR Coated
	Glan-Taylor	Uncoated / AR Coated
	Double Glan-Taylor	Mounted
	Glan-Thompson	Unmounted
		Mounted
	Wollaston Prism	Uncoated / AR Coated

• G. Ghosh. Dispersion-Equation Coefficients for the Refractive Index and Birefringence of Calcite and Quartz Crystals, Opt. Commun. 163, 95-102 (1999)
• The range listed here is for the transmission through a calcite substrate. Some products use optical cement or other materials that can limit the transmission wavelength range.

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Calcite (CaCO₃), or Iceland Spar, is a useful crystalline substrate most commonly used in polarization optics. A calcite polarizer can be designed as either a polarization splitter/combiner or as a polarizer element that removes the angled, orthogonally polarized component of a beam. Since calcite is a soft crystal that is easily damaged, almost all of our calcite polarizers are offered in metal housings. With convenient threadings and adapters, these housings can easily be mounted into our optomechanical products. The transmission data above was taken through an uncoated Glan-Laser calcite polarizer. Calcite has a transmission range from 300 nm to 2.3 μm. It has an ordinary refractive index of 1.642 and an extraordinary refractive index of 1.480 at 1.064 µm. It is not recommended to use these polarizers for input beams with wavelengths greater than 2.3 µm, as calcite has different absorption coefficients for the ordinary and extrarodinary rays that diverge past this point.

Click on the images below or open the table to the right to see Thorlabs’ complete selection of optics made from calcite.

Calcium Fluoride Specifications
Index of Refractiona
Index of Refraction at Nd:YAG (1.064 µm)a	1.428
Sellmeier Equationa
Abbe Number (Vd)	95.31
Transmission Range	180 nm - 8.0 µm
Fresnel Reflectance and Transmittance (Calculated)
Density	3.18 g/cm3
Knoop Hardness	158.3 kg/mm2
Young's Modulus	75.8 GPa
Shear Modulus	33.77 GPa
Bulk Modulus	82.71 GPa
Poisson's Ratio	0.26
Coefficient of Thermal Expansion	18.85 x 10-6 /°C
Heat Capacity	0.854 J/(g*K)
Melting Point	1418 °C
Change in Index of Refraction with Temperature (+20/+40°C @ 1060 nm)	-10.6 x 10-6 /°C

Calcium Fluoride Optics Selection

Spherical Lenses	Plano-Convex	Uncoated
		D Coated (1.65 - 3 µm)
		E Coated (2 - 5 µm)
	Bi-Convex	Uncoated / AR Coated
	Plano-Concave	Uncoated
		E Coated (2 - 5 µm)
	Bi-Concave	Uncoated / AR Coated
	Positive Mensicus	Uncoated
		E Coated (2 - 5 µm)
	Negative Mensicus	Uncoated
		E Coated (2 - 5 µm)
Cylindrical Lenses	Plano-Convex	Uncoated
		D Coated (1.65 - 3 µm)
		E Coated (2 - 5 µm)
Beamsplitters	Non-Polarizing Plate	1 - 6 µm
		2 -8 µm
Windows	Flat	Uncoated
		D coated (1.65 - 3 µm)
	Wedged	Uncoated
Prisms	Dispersion Compensating	Uncoated
	Equilateral Dispersing	Uncoated
	Pellin Broca	Uncoated
	Right Angle	Uncoated
Polarizers	Wire Grid	Holographic

• H. H. Li. Refractive index of alkaline earth halides and its wavelength and temperature derivatives. J. Phys. Chem. Ref. Data 9, 161-289 (1980)

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Calcium Fluoride (CaF₂) is transparent from the UV to the IR (180 nm - 8.0 µm). It has a refractive index of 1.428 at 1.064 µm and is mechanically and environmentally stable. CaF₂ is ideal for any demanding applications where its high damage threshold, low fluorescence, and high homogeneity are beneficial. It is popular in excimer laser applications and frequently used in spectroscopy and cooled thermal imaging.

Click on the images below or open the table to the right to see Thorlabs’ complete selection of optics made from CaF₂.

F2 Specifications
Index of Refractiona
Refractive Index at d-Line (587.6 nm)a	1.620
Sellmeier Equationa
Abbe Number (Vd)	36.37
Attenuation Coefficient
Transmission Range	385 nm - 2 µm
Fresnel Reflectance and Transmittance (Calculated)
Density	3.6 g/cm3
Knoop Hardness (100 g Load)	420 kg/mm2
Young's Modulus	57 GPa
Shear Modulus (calculated value)	23.4 GPa
Bulk Modulus (calculated value)	33.9 GPa
Poisson's Ratio	0.22
Coefficient of Thermal Expansion	8.2 x 10-6 /°C
Heat Capacity	0.557 J/(g*K)
Softening Point	580°C
Change in Index of Refraction with Temperature	2.7 x 10-6 /°C

F2 Optics Selection

Equilateral Dispersive Prisms

Unmounted

• SCHOTT Optical Glass Data sheets July 22, 2015

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F2 is a flint glass that offers excellent performance in the visible and NIR spectral ranges. It is is characterized by a high refractive index and low Abbe number, making it excellent for use as an equilateral dispersive prism. Compared to N-SF11, it offers superior chemical resistance and slightly higher transmission. F2 has a transmission range from 385 nm to 2 µm and a refractive index of 1.620 at 587.6 nm.

Click on the images below or open the table to the right to see Thorlabs’ complete selection of optics made from F2.

Germanium Specifications
Index of Refractiona
Index of Refraction at CO2 Line (10.6 µm)a	4.004
Sellmeier Equationa
Abbe Number (Vd)	Not Defined
Transmission Range	2.0 - 16 µm
Fresnel Reflectance and Transmittance (Calculated)
Density	5.33 g/cm3
Knoop Hardness	780 kg/mm2
Young's Modulus	102.7 GPa
Shear Modulus	67.04 GPa
Bulk Modulus	77.2 GPa
Poisson's Ratio	0.278
Coefficient of Thermal Expansion	6.1 x 10-6 /°C
Heat Capacity	0.310 J/(g*K)
Melting Point	936 °C
Change in Index of Refraction with Temperature (@ 10.6 μm)	277 x 10-6 /°C

Germanium Optics Selection

Spherical Lenses	Plano-Convex	F-Coated (8 - 12 µm)
Windows	Flat	Uncoated
		F-Coated (8 - 12 µm)
	Wedged	Uncoated

• Icenogle et al.. Refractive Indexes and Temperature Coefficients of Germanium and Silicon Appl. Opt. 15 2348-2351 (1976)

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Due to its broad transmission range (2.0 - 16 µm) and opacity in the visible portion of the spectrum, Germanium (Ge) is well suited for IR laser applications. This makes it an ideal choice for biomedical and military imaging applications. In addition, Ge is inert to air, water, alkalis, and acids (except nitric acid). Germanium's transmission properties are highly temperature sensitive; in fact, the absorption becomes so large that germanium is nearly opaque at 100 °C and completely non-transmissive at 200 °C. Ge has an index of refraction of 4.004 at 10.6 µm.

When handling optics, one should always wear gloves. This is especially true when working with germanium, as dust from the material is hazardous. For your safety, please follow all proper precautions, including wearing gloves when handling this material and thoroughly washing your hands afterward. Click here to download a pdf of the MSDS for germanium.

Click on the images below or open the table to the right to see Thorlabs’ complete selection of optics made from germanium.

Magnesium Fluoride Specifications
Index of Refractiona
Index of Refraction at d-Line (587.6 nm)a	ne = 1.378 no = 1.390
Sellmeier Equation, Extraordinarya
Sellmeier Equation, Ordinarya
Abbe Number (Vd), Extraordinary	104.86
Abbe Number (Vd), Ordinary	106.22
Transmission Range	200 nm - 6.0 µm
Fresnel Reflectance and Transmittance, Extraordinary (Calculated)
Fresnel Reflectance and Transmittance, Ordinary (Calculated)
Density	3.177 g/cm3
Knoop Hardness	415 kg/mm2
Young's Modulus	138.5 GPa
Shear Modulus	54.66 GPa
Bulk Modulus	101.32 GPa
Poisson's Ratio	0.276
Coefficient of Thermal Expansion	13.70 x 10-6 /°C (Parallel) 8.48 x 10-6 /°C (Perpendicular)
Heat Capacity	1.003 J/(g*K)
Melting Point	1255 °C
Change in Index of Refraction with Temperature (@ 400 nm)	2.3 x 10-6 /°C (Parallel) 1.7 x 10-6 /°C (Perpendicular)

Magnesium Fluoride Optics Selection

Spherical Lenses		Plano-Convex, Uncoated
Windows	Flat	Uncoated
	Wedged	Uncoated

• M. J. Dodge. Refractive Properties of Magnesium Fluoride, Appl. Opt. 23, 1980-1985 (1984)

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Magnesium Fluoride (MgF₂) is a synthetic crystalline substrate, transparent over a wide range of wavelengths. Transmitting from 200 nm to 6.0 µm, magnesium fluoride is well suited for applications ranging from the UV to the IR. MgF₂ is very rugged and durable, making it useful in high-stress environments. It is commonly used in machine vision, microscopy, and industrial applications. Magnesium fluoride has an ordinary refractive index of 1.390 and an extraordinary refractive index of 1.378 at 587.6 nm.

Click on the images below or open the table to the right to see Thorlabs’ complete selection of optics made from MgF₂.

N-BK7 Specifications
Index of Refractiona
Index of Refraction at d-Line (587.6 nm)a	1.517
Sellmeier Equationa
Abbe Number (Vd)	64.17
Attenuation Coefficient
Transmission Range	350 nm - 2.0 µm
Fresnel Reflectance and Transmittance (Calculated)
Density	2.51 g/cm3
Knoop Hardness	520 kg/mm2
Young's Modulus	82 GPa
Shear Modulus (Calculated Value)	34.0 GPa
Bulk Modulus (Calculated Value)	46.5 GPa
Poisson's Ratio	0.206
Coefficient of Thermal Expansion	7.1 x 10-6 /°C
Heat Capacity	0.858 J/(g*K)
Softening Point	550 °C
Change in Index of Refraction with Temperature (+20/+40°C @ 1060 nm)	2.4 x 10-6 /°C

N-BK7 Optics Selection

Spherical Lenses	Plano-Convex	Uncoated, Unmounted
		Uncoated, Mounted
		V-Coated (780, 633, 1064/532 nm)
		A Coated (350-700 nm), Unmounted
		A Coated (350-700 nm), Mounted
		B Coated (650-1050 nm), Unmounted
		B Coated (650-1050 nm), Mounted
		C Coated (1050-1620 nm), Unmounted
		C Coated (1050-1620 nm), Mounted
	Bi-Convex	Uncoated
		A Coated (350-700 nm)
		B Coated (650-1050 nm)
		C Coated (1050-1620 nm)
	Plano-Concave	Uncoated
		A Coated (350-700 nm)
		B Coated (650-1050 nm)
		C Coated (1050-1620 nm)
	Bi-Concave	Uncoated / AR Coated
	Best Form	Uncoated
		A Coated (350-700 nm)
		B Coated (650-1050 nm)
		C Coated (1050-1620 nm)
	Positive Meniscus	Uncoated / AR Coated
	Negative Meniscus	Uncoated / AR Coated
Cylindrical Lenses	Plano-Convex	Round
		Uncoated
		A Coated (350-700 nm)
		B Coated (650-1050 nm)
		C Coated (1050-1620 nm)
	Plano-Concave	Round
		Uncoated
		A Coated (350-700 nm)
		B Coated (650-1050 nm)
		C Coated (1050-1620 nm)
Windows	Flat	Uncoated / AR Coated
		V Coated
	Wedged	Uncoated / AR Coated
		V-Coated
Beamsplitters	Non-Polarizing Cubes	400 - 700 nm, Unmounted
		700 - 1100 nm, Unmounted
		1100 - 1600 nm, Unmounted
		Mounted
Prisms	Retroreflectors	Uncoated / AR Coated, Unmounted
		Uncoated / AR Coated, Mounted
	Right Angle	Uncoated / AR Coated
	Dove	Uncoated
	Penta	Unmounted
		Mounted
	Roof	Uncoated
	Wedged	AR Coated
	Pellin Broca	Uncoated
	Fresnel Rhomb Retarder	Uncoated
Polarizers	Economy	Unmounted
Diffusers	Ground Glass	Unmounted / Mounted

• SCHOTT Optical Glass Data sheets July 22, 2015

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N-BK7 is a RoHS-compliant borosilicate crown glass. It has excellent transmission in the visible and near IR portions of the spectrum (350 nm - 2.0 µm). N-BK7 is probably the most common optical glass used in high-quality optical components. N-BK7 is a hard glass that can withstand a variety of physical and chemical stressors. It is relatively scratch and chemical resistant. It also has a low bubble and inclusion content, making it a useful glass for precision lenses. The index of refraction of N-BK7 is 1.517 at 587.6 nm.

Click on the images below or open the table to the right to see Thorlabs’ complete selection of optics made from N-BK7.

N-SF11 Specifications
Index of Refractiona
Index of Refraction at d-Line (587.6 nm)a	1.785
Sellmeier Equationa
Abbe Number (Vd)	25.68
Attenuation Coefficient
Transmission Range	420 nm - 2.3 µm
Fresnel Reflectance and Transmittance (Calculated)
Density	3.22 g/cm3
Knoop Hardness	615 kg/mm2
Young's Modulus	92 GPa
Shear Modulus (Calculated Value)	36.6 GPa
Bulk Modulus (Calculated Value)	63.1 GPa
Poisson's Ratio	0.257
Coefficient of Thermal Expansion	8.5 x 10-6 /°C
Heat Capacity	0.710 J/(g*K)
Softening Point	592 °C
Change in Index of Refraction with Temperature (+20/+40°C @ 1060 nm)	0.1 x 10-6 /°C

N-SF11 Optics Selection

Spherical Lenses	Plano-Concave	Uncoated
		A Coated (350-700 nm)
		B Coated (650-1050 nm)
		C Coated (1050-1620 nm)
	Bi-Concave
Prisms	Anamorphic Pairs
	Equilateral Dispersing

• SCHOTT Optical Glass Data sheets July 22, 2015

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N-SF11 is a RoHS-compliant dense-flint glass that is transparent from 420 nm to 2.3 µm. This glass exhibits higher dispersion than N-BK7 but many of its other properties are comparable. With a high index of refraction and a low Abbe number, N-SF11 has high dispersive power and is ideal for applications in the visible range that require high dispersion. Its index of refraction is 1.785 at 587.6 nm.

Click on the images below or open the table to the right to see Thorlabs’ complete selection of optics made from N-SF11.

Potassium Bromide Specifications
Index of Refractiona
Index of Refraction at CO2 Line (10.6 µm)a	1.525
Sellmeier Equationa
Abbe Number (Vd)	33.64
Transmission Range	250 nm - 26 µm
Fresnel Reflectance and Transmittance (Calculated)
Density	2.75 g/cm3
Knoop Hardness	7 kg/mm2
Young's Modulus	26.8 GPa
Shear Modulus	5.08 GPa
Bulk Modulus	15.03 GPa
Poisson's Ratio	0.3
Coefficient of Thermal Expansion	43 x 10-6 /°C
Heat Capacity	0.435 J/(g*K)
Melting Point	730 °C
Change in Index of Refraction with Temperature (+20/+40°C @ 1060 nm)	-40.83 x 10-6 /°C

Potassium Bromide Optics Selection

Windows

Flat

Uncoated

• H. H. Li. Refractive index of alkali halides and its wavelength and temperature derivatives. J. Phys. Chem. Ref. Data 5, 329-528 (1976)

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Potassium Bromide (KBr) is transparent from the UV to the IR (250 nm - 26 µm). It has a refractive index of 1.525 at 10.6 µm and is mechanically stable. KBr is commonly used in infrared optical windows as well as InGaAs and liquid sample cells. Common applications include infrared and FTIR spectrophotometry. KBr is soft and hygroscopic, so optical components should be protected from excess moisture such as high humidity environments.

Click on the images below or open the table to the right to see Thorlabs’ complete selection of optics made from KBr.

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Thorlabs provides plastic plano-convex lenses made with Polytetrafluoroethylene (Virgin White PTFE), which has a low dielectric constant of approximately 1.96 at 520 GHz and an index of refraction of 1.4. The low dielectric constant of PTFE ensures that the insertion loss is reasonably low.

PTFE is especially useful for application in the Terahertz range, which is defined as the frequency range from 300 GHz to 10 THz, or the wavelength range of 30 μm to 1 mm. The THz band has been gaining popularity in applications such as spectroscopy, astronomy, remote sensing, and in security (THz imaging). The THz band is situated between microwaves and optics on the electromagnetic spectrum. This location influences the mixture of microwave and optical technologies used in the THz band.

Click on the image below or open the table to the right to see Thorlabs’ complete selection of optics made from PTFE.

Rutile Specifications
Index of Refractiona
Index of Refraction at Nd:YAG (1.064 µm)a	ne = 2.734 no = 2.482
Sellmeier Equation, Extraordinarya
Sellmeier Equation, Ordinarya
Abbe Number (Vd), Extraordinary	Not Defined
Abbe Number (Vd), Ordinary	Not Defined
Transmission Range	500 nm - 4.5 µm
Fresnel Reflectance and Transmittance, Extraordinary (Calculated)
Fresnel Reflectance and Transmittance, Ordinary (Calculated)
Density	4.25 g/cm3
Knoop Hardness	879 kg/mm2
Young's Modulus*	-
Shear Modulus	112.4 GPa
Bulk Modulus	215.5 GPa
Poisson's Ratio	0.28
Coefficient of Thermal Expansion	9.2 x 10-6 /°C (Parallel) 7.1 x 10-6 /°C (Perpendicular)
Heat Capacity	0.711 J/(g*K)
Melting Point	1840°C
Change in Index of Refraction with Temperature	-0.42 x 10-6 /°C (Parallel) -0.72 x 10-6 /°C (Perpendicular)

Rutile Optics Selection

Coupling Prisms	Unmounted
Polarizers	AR-Coated (2.2 - 4 µm)

• Borne, Adrien & et al. (2012). Optical Materials Express, 2(12) Refractive indices, phase-matching directions and third order nonlinear coefficients of rutile TiO2 from third harmonic generation.
• Value cannot be calculated because rutile is an anisotropic material. For more information, please see the Tutorial tab.

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Click on the images below or open the table to the right to see Thorlabs’ complete selection of optics made from rutile.

Sapphire Specifications
Index of Refractiona
Index of Refraction at Nd:YAG (1.064 µm)a	ne = 1.747 no = 1.754
Sellmeier Equation, Extraordinarya
Sellmeier Equation, Ordinarya
Abbe Number (Vd), Extraordinary	72.99
Abbe Number (Vd), Ordinary	72.31
Transmission Range	150 nm - 4.5 µm
Fresnel Reflectance and Transmittance, Extraordinary (Calculated)
Fresnel Reflectance and Transmittance, Ordinary (Calculated)
Density	3.97 g/cm3
Knoop Hardness	2000 kg/mm2
Young's Modulus	335 GPa
Shear Modulus	148.1 GPa
Bulk Modulus	240 GPa
Poisson's Ratio	0.25
Coefficient of Thermal Expansion	5.3 x 10-6 /°C (Parallel) 4.5 x 10-6 /°C (Perpendicular)
Heat Capacity	0.335 J/(g*K)
Softening Point	1800 °C
Change in Index of Refraction with Temperature (@ 0.546 μm)	13.1 x 10-6/°C

Sapphire Optics Selection

Windows	Flat	Uncoated
		D Coated (1.65 - 3.0 µm)
		E1 Coated (2.0 - 5.0 µm)
	Wedged	Uncoated
		E1 Coated (2.0 - 5.0 µm)

• I. H. Malitson and M. J. Dodge. Refractive Index and Birefringence of Synthetic Sapphire, J. Opt. Soc. Am. 62, 1405 (1972)

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Sapphire (Al₂O₃) has exceptional surface hardness and can only be scratched by a few materials other than itself. This hardness allows it to be made into much thinner optics than other substrates. Sapphire is chemically inert and insoluble to water, common acids, and alkalis for temperatures up to 1,000 °C. Sapphire is transparent in the UV to the IR (150 nm - 4.5 µm). It is commonly used in IR laser systems and has an ordinary refractive index of 1.754 and an extraordinary refractive index of 1.747 at 1.064 µm.

Click on the images below or open the table to the right to see Thorlabs’ complete selection of optics made from sapphire.

Silicon Specifications
Index of Refractiona
Index of Refraction at 4.58 µma	3.423
Sellmeier Equationa
Abbe Number (Vd)	Not Defined
Transmission Range	1.2 - 8.0 µm
Fresnel Reflectance and Transmittance (Calculated)
Density	2.329 g/cm3
Knoop Hardness	1100 kg/mm2
Young's Modulus	130.91 GPa
Shear Modulus	79.92 GPa
Bulk Modulus	101.97 GPa
Poisson's Ratio	0.28
Coefficient of Thermal Expansion	4.50 x 10-6 /°C
Heat Capacity	0.84 J/(g*K)
Melting Point	1690 °C
Change in Index of Refraction with Temperature (@ 10.6 μm)	160 x 10-6 /°C

Silicon Optics Selection

Spherical Lenses	Plano-Convex	E-Coated (2 - 5 µm)
Windows	Flat	Uncoated
		E-Coated (3 - 5 µm)
	Wedged	Uncoated

• C. D. Salzberg and J. J. Villa. Infrared Refractive Indexes of Silicon, Germanium and Modified Selenium Glass, J. Opt. Soc. Am. 47, 244-246 (1957)

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Silicon (Si) lenses and windows are an ideal choice for applications using wavelengths in the near-IR range and parts of the mid-IR range. Silicon offers high thermal conductivity and low density, making it suitable for laser mirrors. However, since silicon has a strong absorption band at 9 µm, it is not suitable for use with CO₂ laser transmission applications. Silicon optics are also particularly well suited for imaging, biomedical, and military applications. Our Quantum Cascade Lasers offer a number of output wavelengths for use with silicon optics. Silicon has a transmission range from 1.2 µm to 8.0 µm. Silicon has a refractive index of 3.423 at 4.58 µm. 

Click on the images below or open the table to the right to see Thorlabs’ complete selection of optics made from silicon.

UV Fused Silica Specifications
Index of Refractiona
Index of Refraction at d-Line (587.6 nm)a	1.458
Sellmeier Equationa
Abbe Number (Vd)	67.82
Transmission Range	185 nm - 2.1 µm
Fresnel Reflectance and Transmittance (Calculated)
Density	2.203 g/cm3
Knoop Hardness	461 kg/mm2
Young's Modulus	73.6 GPa
Shear Modulus (Calculated Value)	31.4 GPa
Bulk Modulus (Calculated Value)	37.2 GPa
Poisson's Ratio	0.17
Coefficient of Thermal Expansion	0.55 x 10-6 /°C
Heat Capacity	0.736 J/(g*K)
Softening Point	1585 °C
Change in Index of Refraction with Temperature (+20/+40°C @ 1060 nm)	11.9 x 10-6 /°C

UV Fused Silica Optics Selection

Spherical Lenses	Plano-Convex	Uncoated, Unmounted
		Uncoated, Mounted
		UV Coated (245-400 nm), Unmounted
		UV Coated (290-370 nm), Mounted
		A Coated (350-700 nm), Unmounted
		B Coated (650-1050 nm), Unmounted
		C Coated (1050-1700 nm), Unmounted
		V Coated (532/1064 nm), Unmounted
	Bi-Convex	Uncoated
		UV Coated (245-400 nm)
		A Coated (350-700 nm)
		B Coated (650-1050 nm)
		C Coated (1050-1620 nm)
	Plano-Concave	Uncoated
		UV Coated (245-400 nm)
		A Coated (350-700 nm)
		B Coated (650-1050 nm)
		C Coated (1050-1620 nm)
	Bi-Concave	Uncoated
		UV Coated (245-400 nm)
	Positive Meniscus	Uncoated
		UV Coated (245-400 nm)
	Negative Meniscus	Uncoated / AR Coated
Cylindrical Lenses	Plano-Convex	Uncoated / AR Coated
	Plano-Concave	Uncoated / AR Coated
Beamsplitters	Non-Polarizing Plate	250 - 450 nm
		400 - 700 nm
		700 - 1100 nm
		350 - 700 nm
		600 - 1700 nm
		1.2 - 1.6 µm
	Polarizing Plate	532 - 1550 nm
	Wedged Plate	185 nm - 2.1 µm
	Beam Samplers	Coated
	Polarizing Cubes	Unmounted
		Cube Mounted
	Polarizing High Power Cubes	Unmounted
		Cube Mounted
	Brewster Window	Unmounted
	Polka Dot Beamsplitter	Unmounted
	Hot/Cold Mirrors	Unmounted
	Dichroic Mirror/Beamsplitters	Unmounted
	Nd:YAG Harmonic Beamsplitters	Unmounted
Prisms	Right Angle	Uncoated
	Axicons	AR Coated
	Pellin Broca	Uncoated
Windows	Non-Wedged	Uncoated / AR Coated
		V-Coated
	Wedged	Uncoated / AR Coated
		V-Coated
	High-Vacuum CF Flange	Unmounted / Mounted
Diffusers	Ground Glass	Unmounted

• I. H. Malitson. Interspecimen Comparison of the Refractive Index of Fused Silica, J. Opt. Soc. Am. 55, 1205-1208 (1965)

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UV-Grade Fused Silica (UVFS) is ideal for use in applications in the UV range that go beyond the transmission of N-BK7. When compared to N-BK7, UV fused silica is transparent over a wider range of wavelengths (185 nm - 2.1 µm) and also offers a lower index of refraction as well as better homogeneity. It is scratch resistant and has a low coefficient of thermal expansion. UV fused silica exhibits minimal fluorescence when exposed to wavelengths longer than 290 nm. Its index of refraction is 1.458 at 587.6 nm.

Click on the images below or open the table to the right to see Thorlabs’ complete selection of optics made from UVFS.

Yttrium Orthovanadate Specifications
Index of Refractiona
Index of Refraction at Nd:YAG (1.064 µm)a	no = 1.959 ne = 2.166
Sellmeier Equation, Extraordinarya
Sellmeier Equation, Ordinarya
Abbe Number (Vd), Extraordinary	18.10
Abbe Number (Vd), Ordinary	20.29
Transmission Range	488 nm - 3.4 µm
Fresnel Reflectance and Transmittance, Extraordinary (Calculated)
Fresnel Reflectance and Transmittance, Ordinary (Calculated)
Density	4.23 g/cm3
Knoop Hardness	480 kg/mm2
Young's Modulus	133 GPa
Coefficient of Thermal Expansion	11 x 10-6 /°C (Parallel) 4.4 x 10-6 /°C (Perpendicular)
Heat Capacity	0.51 J/(g*K)
Melting Point	1750 - 1940 °C
Change in Index of Refraction with Temperature (@ 632.8 nm)	2.9 x 10-6 /°C (Parallel) 8.5 x 10-6 /°C (Perpendicular)

Yttrium Orthovanadate Optics Selection

Beam Displacers	Mounted and Unmounted
Wollaston Prisms	Mounted

• H. S. Shi, G. Zhang and H. Y. Shen. Measurement of Principal Refractive Indices and the Thermal Refractive Index Coefficients of Yttrium Vanadate, J. Synthetic Cryst. 30, 85-88 (2001)

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Yttrium Orthovanadate (YVO₄) is a positive uniaxial crystal that is primarily used for polarization optics. It has a large birefringence and a wide transparency range that extends into the infrared, making it ideal for IR polarizers.

Click on the images below or open the table to the right to see Thorlabs’ complete selection of optics made from yttrium orthovanadate.

Zerodur® Specifications
Index of Refractiona
Index of Refraction at d-Line 587.6 nma	1.542
Sellmeier Equationa
Abbe Number (Vd)	56.12
Fresnel Reflectance and Transmittance (Calculated)
Density	2.53 g/cm3
Knoop Hardness	620 kg/mm2
Young's Modulus	90.3 GPa
Shear Modulus (Calculated Value)	36.4 GPa
Bulk Modulus (Calculated Value)	57.9 GPa
Poisson's Ratio	0.24
Coefficient of Thermal Expansion	0 ± 0.100 x 10-6 /°C
Heat Capacity	0.80 J/(g*K)
Maximum Application Temperature	600 °C

Zerodur Optics Selection

Plano Mirrors	Blanks
	Broadband Dielectric Coating
	Metallic Coating

• SCHOTT Technical Information: Optical Properties of ZERODUR, November 2007

Zerodur^® is a glass ceramic with an extremely low coefficient of thermal expansion (CTE). This material is produced by Schott, and is used to manufacture mirrors for demanding applications that are sensitive to thermally-induced drift. Chemically, it is an inorganic, non-porous lithium aluminum silicon oxide glass ceramic that consists of evenly distributed nanoscale crystals in a glass phase. It displays excellent CTE homogeneity and chemical stability, and is frequently utilized in high-precision optical systems. Transmission data and specifications are not provided for Zerodur because Thorlabs only offers reflective Zerodur optics.

Click on the images below or open the table to the right to see Thorlabs’ complete selection of optics made from Zerodur.

Zinc Selenide Specifications
Index of Refractiona
Index of Refraction at CO2 Line (10.6 µm)a	2.403
Sellmeier Equationa
Abbe Number (Vd)	Not Defined
Transmission Range	600 nm - 16 µm
Fresnel Reflectance and Transmittance (Calculated)
Density	5.27 g/cm3
Knoop Hardness	112 kg/mm2
Young's Modulus	67.2 GPa
Shear Modulus*	34 GPa
Bulk Modulus	40 GPa
Poisson's Ratio	0.28
Coefficient of Thermal Expansion	7.1 x 10-6 /°C
Heat Capacity	0.399 J/(g*K)
Melting Point	1520 °C
Change in Index of Refraction with Temperature (@ 10.6 μm)	61 x 10-6 /°C

Zinc Selenide Optics Selection

Spherical Lenses		Plano-Convex, F-Coated (8 - 12 µm)
		Bi-Convex, F-Coated (8 - 12 µm)
		Plano-Concave, F-Coated (8 - 12 µm)
		Bi-Concave, F-Coated (8 - 12 µm)
		Positive Meniscus, F-Coated (8 - 12 µm)
		Negative Meniscus, F-Coated (8 - 12 µm)
Cylindrical Lenses		Plano-Convex, G-Coated (7 - 12 µm)
Aspheric Lens		E and F Coated (3-5 µm and 8-12 µm)
Axicons		E3 Coated (7-12 µm)
Prisms		Right Angle
		Equilateral Dispersing
Beamsplitters		Non-Polarizing Plate
Windows	Flat	Uncoated
		D Coated (1.65 - 3.0 µm)
		E2 Coated (4.5 - 7.5 µm)
		G Coated (7 - 12 µm)
	Wedged	Uncoated
Polarizers		Wire Grid Holographic

• J. Connolly, B. diBenedetto, and R. Donadio. Specifications of Raytran Material, Proc. SPIE 181, 141-144 (1979)

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Due to its wide transmission band and low absorption in the red portion of the visible spectrum, Zinc Selenide (ZnSe) is commonly used in optical systems that combine CO₂ lasers, operating at 10.6 µm, with inexpensive HeNe alignment lasers. Zinc selenide is transparent from 600 nm - 16 µm and is ideal for IR applications. It is also commonly used in thermal imaging systems. ZnSe also transmits some visible light, unlike germanium and silicon, thereby allowing for visual optical alignment. However, it is quite soft and will scratch easily. ZnSe has an index of refraction of 2.403 at 10.6 µm.

When handling optics, one should always wear gloves. This is especially true when working with zinc selenide, as it is a hazardous material. For your safety, please follow all proper precautions, including wearing gloves when handling ZnSe and thoroughly washing your hands afterward. For the MSDS for ZnSe in English, click here, and for the MSDS in Japanese, click here.

Click on the images below or open the table to the right to see Thorlabs’ complete selection of optics made from ZnSe.

Thorlabs offers a wide range of achromatic lenses with wavelength options ranging from 240 nm to 12 µm. The table below lists the various substrates used in Thorlabs' achromatic lenses. Click here to view Thorlabs' full line of achromatic lenses.

Achromatic Substrate Specifications
Substrate	Uncoated Transmission Range	Uncoated Transmission Graph	Attenuation Coefficient	Abbe Number, Vd	Density (g/cm3)	Knoop Hardness (kg/mm2)	Young Modulus (GPa)	Shear Modulusa (GPa)	Bulk Modulusa (GPa)	Poisson's Ratio	CTEb (x 10-6 /°C)	Specific Heat (J/(g*K))	Tgc (°C)	dn/dTd (x 10-6 /°C)
CaF2	180 nm - 8.0 µm		-	95.31	3.18	158	75.8	33.77e	82.71e	0.26	18.85	0.854	1418	-10.6
UVFS	185 nm - 2.1 µm		-	67.82	2.2	461	73.6	31.5	37.2	0.17	0.55	0.736	~1200	11.9
N-BK7	350 nm - 2 µm			64.17	2.51	610	82	34.0	46.5	0.206	7.1	0.858	557	2.4
N-K5	350 nm - 2.1 µm			59.48	2.59	3.03	71	29.0	42.9	0.224	8.2	0.783	546	1.4
N-KZFS5	350 nm - 2.1 µm			39.7	3.04	555	89	35.8	57.7	0.243	6.4	0.73	584	4.2
N-LAK22	350 nm - 2.1 µm			55.89	3.77	600	90	35.5	64.1	0.266	6.6	0.55	689	2.4
N-SK2	350 nm - 2.3 µm			56.65	3.55	550	78	30.9	54.9	0.263	6	0.595	659	3.6
N-SSK2	350 nm - 2.3 µm			53.27	3.53	570	82	32.5	57.2	0.261	5.8	0.58	653	4.3
N-SSK5	350 nm - 2.2 µm			50.88	3.71	590	88	34.4	66.1	0.278	6.8	0.574	645	2.2
SF2	350 nm - 2.2 µm			33.85	3.86	410	55	22.4	33.6	0.227	8.4	0.498	441	2.7
SF5	350 nm - 2.3 µm			32.21	4.07	410	56	22.7	35.0	0.233	8.2	-	425	3.5
ZnS	370 nm - 13 µm		-	19.86	4.09	160	74.5	-	-	0.28	6.5	0.515	1765	38.7 @ 3.39 µm
FD10 (SF10)	400 nm - 2.3 µm			28.41	4.28	430	64	26.1	39.8	0.232	-	0.465	454	7.5
LAFN7	400 nm - 2 µm			34.95	4.38	520	80	31.3	60.6	0.28	5.3	-	500	6.3
N-BAF10	400 nm - 2.1 µm			47.11	3.75	620	89	35.0	64.8	0.271	6.2	0.56	660	3.8
N-BAF4	400 nm - 2.1 µm			43.72	2.89	610	85	34.5	52.7	0.231	7.2	0.74	580	2.2
N-BAF52	400 nm - 2.1 µm			46.6	3.05	2.42	86	34.8	54.5	0.237	6.9	0.68	594	2.3
N-BAK4	400 nm - 2.2 µm			43.72	2.89	610	85	34.5	52.7	0.231	7	0.74	580	7.2
N-BALF4	400 nm - 2.3 µm			53.87	3.11	540	77	30.9	50.3	0.245	6.5	0.69	578	4.2
N-F2	400 nm - 2.1 µm			36.36	2.65	600	82	33.4	50.2	0.228	7.8	0.81	569	2.1
N-KZFS8	400 nm - 2.2 µm			34.7	3.2	570	103	41.3	68.1	0.248	7.8	0.76	509	2.4
N-LAK10	400 nm - 2 µm			50.62	3.69	780	116	45.1	90.3	0.286	5.7	0.64	636	4.2
N-SF1	400 nm - 2 µm			29.62	3.03	540	90	36.0	60.0	0.25	9.1	0.75	553	0
N-SF2	400 nm - 2.3 µm			33.82	2.72	539	86	34.9	53.3	0.231	6.7	0.69	608	2.6
N-SF4	400 nm - 2.1 µm			27.38	3.15	520	90	35.8	61.5	0.256	9.5	0.76	570	-0.7
N-SF5	400 nm - 2.2 µm			32.25	2.86	620	87	35.2	55.1	0.237	7.9	0.77	578	1.8
N-SF6HT	400 nm - 2.1 µm			25.36	3.37	550	93	36.8	65.1	0.262	9	0.69	589	-0.8
N-SF8	400 nm - 2.1 µm			31.31	2.9	600	88	35.3	57.5	0.245	8.6	0.77	567	0.9
N-SF10	400 nm - 2.3 µm			28.53	3.05	540	87	34.7	58.5	0.252	9.4	0.74	559	-0.5
N-SSK8	400 nm - 2.1 µm			49.83	3.27	570	84	33.6	56.2	0.251	7.2	0.64	616	2.0
SF6HT	400 nm - 2.3 µm			25.43	5.18	370	55	22.1	35.8	0.244	8.1	0.389	423	6.8
SF10	400 nm - 2.3 µm			28.41	4.28	430	64	26.0	39.8	0.232	7.5	0.465	454	5.3
N-SF11	420 nm - 2.3 µm			25.68	3.22	615	92	36.6	63.1	0.257	8.5	0.71	592	0.1
N-SF56	450 nm - 2.2 µm		-	26.1	3.28	560	91	36.3	61.9	0.255	8.7	0.7	592	-0.3
N-SF57	450 nm - 2.1 µm			23.78	3.53	520	96	38.1	66.7	0.26	8.5	0.66	629	-0.5
ZnSe	600 nm - 16 µm		-	-	5.27	112	67.2	-	40.0e	0.28	7.1	0.399	1520	61 @ 10.6 µm
Silicon	1.2 µm - 8.0 µm		-	-	2.33	1150	131	79.9e	102.0e	0.266	4.5	0.703	1417	160 @ 10.6 µm
Germanium	2.0 - 16 µm		-	-	5.33	780	102.7	67e	77.2e	0.28	6.1	0.31	936	277 @ 10.6 µm
E-BAF11	-	-		48.31	-	560	92.9	36.5	68.5	0.274	69	-	-	3.9 @ 6.43 nm

• Values calculated unless otherwise noted.
• Coefficient of thermal expansion
• Transformation temperature
• Change in index of refraction with temperature, measured between 20 and 40°C at 1060 nm, unless otherwise noted.
• Measured value

Thorlabs offers molded plastic, molded glass, and precision-polished aspherical lenses. Listed below are the various substrates used in Thorlabs' aspheric lenses. Click here to view Thorlabs' full line of aspheric lenses.

Aspheric Substrate Specifications
Substrate	Uncoated Transmission Range	Uncoated Transmission Graph	Attenuation Coefficient	Abbe Number, Vd	Density (g/cm3)	Knoop Hardness (kg/mm2)	Young Modulus (GPa)	Shear Modulusa (GPa)	Bulk Modulusa (GPa)	Poisson's Ratio	CTEb (x 10-6 /°C)	Specific Heat (J/(g*K))	Tgc (°C)	dn/dTd (x 10-6 /°C)
Acrylic	380 nm - 1.6 µm		-	52.6	1.18	-	3.2	1.2	3.6	0.35	70	1.465	100	-85
D-K59	380 nm - 2 µm		-	63.1	-	-	-	-	-	-	6.5	-	-	4.3
H-LAK54	380 nm - 2.05 µm		-	51.05	4.01	770	113.87	44.0	92.1	0.294	5.2	0.528	639	5.7 @ 1014 nm
Polycarbonate	380 nm - 1.6 µm		-	27.56	1.21	-	2.24	0.82	2.9	0.37	70.2	1.3	130	-107
B270	380 nm - 2.1 µm		-	58.64	2.54	5.37	74	30.3	44.5	0.223	-	-	-	-
Cyclic Olefin Copolymer	400 nm - 1.50 µm		-	56	1.02	-	3.1	1.1	4.0	0.37	60	-	140	-101
H-ZLAF52	400 nm - 2 µm		-	40.95	4.45	650	111.46	42.6	96.3	0.307	6.2	0.507	599	6.4 @ 1014 nm
S-LAH64	400 nm - 1.9 µm		-	47.3	4.3	750	122.4	47.3	99.0	0.294	6.1	0.491	685	3.7 @ 1014 nm
S-LAL13	400 nm - 2 µm		-	53.34	3.6	650	107.3	41.6	85.2	0.29	5.3	0.574	641	4.9 @ 1014 nm
TAC4	400 nm - 1.9 µm		-	51.05	406	765	112.5	43.3	93.8	0.3	5.2	0.528	630	-
ECO-550	400 nm - 1.7 µm		-	50.28	3.31	254	55.1	27.6	18.4	-	11.62	-	371	-1.3
N-SF57	450 nm - 2 µm			23.78	3.53	520	96	38.1	66.7	0.26	8.5	0.66	629	-0.5
S-NPH1	450 nm - 2 µm		-	22.76	3.29	460	89.3	35.72d	59.5d	0.25	8.3	-	552	-1.8 @ 1014 nm
ZnSe	600 nm - 16 µm		-	-	5.27	112	67.2	n/a	40e	0.28	7.1	0.399	1520	61 @ 10.6 μm
BD-2	1.2 µm - 12 µm		-	-	4.67	150	22.1	11.1	7.4	-	13.5	-	278	91
D-ZLAF52LA	-		-	40.73	4.56	662	11.506	5.8	3.8	-	6.9	-	546	6.5
D-ZK3	-		-	60.71	2.83	628	97.67	39.6	61.2	0.234	7.6	0.816	511	2.3 @ 1014 nm

• Values calculated unless otherwise noted.
• Coefficient of thermal expansion
• Transformation temperature
• Change in index of refraction with temperature, measured between 20 and 40°C at 1060 nm, unless otherwise noted.
• Measured value