BK7 Window

At TC Optik, we are proud to offer high-quality BK7 windowthat are manufactured to the highest standards of precision and quality. Our bk7 optical windowsare made from high-quality borosilicate optical glass with exceptional optical transmission characteristics, and are ideal for a wide range of applications, including imaging, spectroscopy, laser optics, and more. H-K9L is the alternative for N-BK7.H-K9L (N-BK7) is a RoHS-compliant borosilicate crown glass. It provides excellent transmission in the visible and near-infrared portions of the spectrum (350 nm - 2.0 µm). It is typically chosen whenever the additional benefits of UV fused silica. H-K9L (N-BK7) is probably the most common optical glass used in high-quality optical components.

Specification of BK7 Window

Optical windows are an essential component in various optical applications such as laser systems, medical instruments, and scientific research devices. They play a crucial role in protecting optical systems from external elements and ensuring precise measurements by allowing light to pass through with minimal distortion. When it comes to optical windows, the material used is a critical factor in determining the performance and quality of the window. One such material that stands out is N-BK7 glass, which is widely recognized for its superior optical properties and versatility. In this article, we will take a closer look at N-BK7 optical windows and explore their characteristics, applications, and advantages over other materials.




1 to 500 mm

Diameter Tolerance

+0/-0.02 mm

Thickness Tolerance

±0.01 mm

Surface Quality


Surface Figure



1 Minute


Uncoated, AR, HR, Beamsplitter, etc.

Our BK7 windows offer excellent performance and superior durability, thanks to their high scratch resistance and low coefficient of thermal expansion. They are available in a range of standard sizes and thicknesses, or can be custom-manufactured to your exact specifications.

At TC Optik, we use state-of-the-art manufacturing techniques and equipment to ensure that our BK7 windows are of the highest quality. Our experienced engineers and technicians use advanced glass grinding and polishing techniques to achieve the precise dimensional and optical specifications required by our customers, and we are committed to providing exceptional customer service and support.

We offer competitive pricing and fast turnaround times on all of our custom optical window, and are happy to work with you to find the right solution for your specific needs. Contact us today to learn more about our optical window glass and how they can help you achieve your optical needs.

Types of optical window glass for your needs:

Fused silica window

Sapphire optical window

ZnSe window

Germanium window

Silicon window

Borosilicate glass for sale

Float glass optical windows

Understanding N-BK7 Optical Windows

N-BK7 is a type of borosilicate crown glass that contains a precise composition of boron and potassium. This glass is specifically designed to offer exceptional optical transmission in the visible and near-infrared regions. With a refractive index of 1.5168, N-BK7 glass has excellent optical clarity, low dispersion, and high homogeneity, making it an ideal material for optical applications.

N-BK7 optical windows are available in a range of sizes and shapes, including round, rectangular, and square. They are manufactured using precision grinding and polishing techniques to achieve flatness and parallelism within a few arc seconds. Additionally, N-BK7 optical windows can be coated with various anti-reflective coatings to minimize surface reflection and enhance optical performance.

Applications of N-BK7 Optical Windows

N-BK7 optical windows find applications in various fields such as:

Laser Systems

N-BK7 optical windows are commonly used in laser systems for protecting the laser cavity and allowing the laser beam to pass through. They are also used in laser diodes and laser mirrors, where they help to reduce losses and enhance beam quality.

Medical Instruments

N-BK7 optical windows are used in medical instruments such as endoscopes and microscopes for imaging and diagnosis purposes. They help to provide clear and accurate images by minimizing distortion and aberrations.

Scientific Research

N-BK7 optical windows find applications in scientific research devices such as spectrometers, telescopes, and cameras. They are used to measure and analyze light spectra, stars, and other celestial bodies.

Aerospace and Defense

N-BK7 optical windows are widely used in aerospace and defense applications, where they help to protect sensors and other optical components from harsh environments.

Advantages of N-BK7 Optical Windows

N-BK7 optical windows offer several advantages over other materials such as:

High Transmission

N-BK7 glass has a high transmission in the visible and near-infrared regions, making it suitable for a wide range of applications.

Low Dispersion

N-BK7 glass has low dispersion, which means that it can minimize chromatic aberrations and ensure clear and accurate images.


N-BK7 glass is relatively inexpensive compared to other optical materials, making it an affordable choice for various applications.


N-BK7 glass is resistant to thermal and mechanical shock, making it a durable and reliable material for optical windows.


N-BK7 optical windows are a reliable and cost-effective choice for various optical applications. With their superior optical properties and versatility, they offer high transmission, low dispersion, and durability, making them ideal for use in laser systems, medical instruments, scientific research devices, and aerospace and defense applications. Their availability in various shapes and sizes, along with the option to customize coatings, makes them a versatile choice for any optical system.

In summary, N-BK7 optical windows are an ideal choice for various optical applications due to their superior optical properties, versatility, and cost-effectiveness. With their high transmission, low dispersion, and durability, they offer clear and accurate imaging while protecting optical systems from external elements. By customizing the size, shape, and coating of N-BK7 optical windows, they can be tailored to meet specific application requirements.

TC Optics is a professional precision optics manufacturers, we provide optical component design, bk7 fused silica, ir bandpass filter 940nm, uv bandpass filter filmand etc. Contact us to know bk7 glass priceor more.

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