With a wide range of substrates available for UV and IR applications, Such as: N-BK7, Fused Silica, Magnesium fluoride, Zinc Selenide, Silicon, Germanium,Sapphire.etc. You might wonder which one is best suited for your specific needs. To determine the optimal substrate for your requirements, it is essential to consider factors such as desired Wavelength Range, mechanical properties, thermal stability, and cost-effectiveness.

First, Wavelength Range

Identify the wavelength range relevant to your application. Different substrates exhibit varying transmission properties across the UV and IR  Spectrum . Match the substrate's transmission characteristics with your desired wavelength range.The Chart of Substrate Comparison as follow：

• N-BK7, with hith cost-effective and good transmission down to 350nm, covering the visible and near-infrared (NIR). wavelength range ,BK7 serves as a suitable substrate for machine vision, microscopy, and industrial applications.

• Fused Silica, with excellent transmission across the UV to IR spectrum is an ideal substrate for interferometry, laser instrumentation, spectroscopy, and industrial applications.

• Calcium Fluoride ( CaF2 ), With its low absorption coefficient, high damage threshold, and transmission range spanning from 0.2 to 7μm, Calcium Fluoride proves to be a suitable substrate for applications such as spectroscopy, semiconductor processing, and cryogenically cooled thermal imaging.

• Magnesium fluoride ( MgF2 ), with its excellent broadband transmission from deep ultraviolet (DUV) to mid-IR, is ideal for applications involving UV and IR laser systems, rugged environmental equipment, and high-vibration environments.

• Zinc Selenide ( Znse ), with its broad wavelength range, low absorption coefficient, and high resistance to thermal shock, is well-suited for applications such as CO2 laser systems and thermal imaging.

• Silicon ( Si ), with its varied transmission across the infrared (IR) spectrum, is commonly used for applications such as spectroscopy, mid-IR laser systems, and THz imaging.

• Germanium ( Ge ), with its transmission characteristics varying across the infrared (IR) spectrum, is well-suited for applications in thermal imaging, FLIR (forward-looking infrared), and rugged IR applications, particularly in the mid and far-IR regions.

• Sapphire, with its good transmission from UV to IR, is well-suited for applications such as IR laser systems, spectroscopy, and rugged environmental equipment.

Second, Mechanical Properties

Assess the mechanical requirements of your application. Consider factors such as hardness, flexibility, and resistance to environmental conditions.BK7 exhibits moderate mechanical strength and hardness, while Fused silica and Sapphire demonstrate high mechanical strength and hardness. Calcium fluoride, Zinc selenide, and Silicon have low to moderate mechanical strength and hardness. Germanium and Magnesium fluoride exhibit moderate to high mechanical strength and hardness. Overall, these materials generally have low fragility.Choose a suitable substrate that can withstand the mechanical stresses and conditions it will encounter.

Third, Thermal Stability

Evaluate the thermal properties required for your application. Consider factors such as coefficient of thermal expansion, thermal conductivity, and maximum operating temperature.. BK7, Fused silica, Sapphire, Calcium fluoride, Zinc selenide, Silicon, Germanium, and Magnesium fluoride exhibit varying levels of thermal stability, with Fused silica, Sapphire, and Magnesium fluoride demonstrating excellent thermal stability, while the others possess moderate thermal stability.Select a suitable substrate that can handle the temperature variations and thermal stresses it will be subjected to.

Four, Cost Considerations

While some materials may offer superior optical properties, they might be more expensive or harder to source. Strike a balance between performance and affordability.BK7 and Fused silica offer cost-effective options, while Sapphire, Calcium fluoride, Zinc selenide, Silicon, Germanium, and Magnesium fluoride tend to have higher costs associated with their unique properties and manufacturing processes.

Five, Consultation and Actual testing

You should consult optical experts or suppliers with extensive knowledge of the available substrates to receive guidance based on their expertise, which will assist you in making an informed decision. Furthermore, it is recommended to conduct feasibility studies or prototype testing to validate the suitability of a specific substrate for your application. This practical approach will provide valuable insights and ensure that the chosen substrate effectively meets your requirements.

In summary

When choosing a substrate for UV and IR applications, it is crucial to consider factors such as wavelength range, mechanical properties, thermal stability, and cost. BK7 and Fused silica are cost-effective options with good transmission properties. Sapphire offers good transmission and high mechanical strength. Calcium fluoride has low absorption and high damage threshold. Zinc selenide is suitable for broad wavelength range and thermal imaging. Silicon and Germanium have varied transmission properties in the IR spectrum. Magnesium fluoride offers excellent transmission and thermal stability. Overall, consulting with experts and conducting feasibility studies can help in selecting the optimal substrate for your specific needs.