Sales Engineer: Grace Gao

Email: grace@rsnv.cn

WhatsApp: +86 199 2997 5286

Q: What is an AR coated optical window, and what specifications do you offer?

A: Our AR coated optical window is a precision planar component designed to transmit laser light with minimal reflection loss while protecting sensitive internal optics from dust, spatter, and moisture. It features a broadband anti-reflection coating achieving <0.1% reflectivity at 1064nm, 532nm, and 650nm — three key wavelengths for Nd:YAG laser systems. The window is manufactured from K9 optical glass or fused silica, available in standard diameters of Φ20 mm and Φ18 mm, with custom sizes supported upon request. The uncoated edge features a ground frosted finish to reduce edge glare and handling damage.

Q: What does the optical window look like from different angles?

A: The optical window is a cylindrical planar component with three distinct views. The front face provides a circular clear aperture where the broadband AR coating is applied, ensuring >99.9% transmission at the specified wavelengths. The edge profile shows the precise thickness and ground frosted edge finish, which minimizes edge reflections and facilitates secure mounting. The 3/4 view combines both perspectives, illustrating how the window integrates into a laser system — a thin, flat optical disk that mounts perpendicular to the beam path, allowing 100% straight-through transmission with zero beam deviation.

Q: How do I choose between K9 glass and fused silica for my laser window?

A: The choice depends on your application requirements. K9 glass is the economy option with a transmission range of 350-2100nm, making it suitable for visible to near-IR applications. It can withstand maximum temperatures up to 600°C and is recommended for low to medium laser power applications where cost is a primary consideration.

Fused silica is the premium option with an extended transmission range of 190-2500nm, covering UV to near-IR wavelengths. It offers a much higher maximum temperature rating of 1100°C and is specifically recommended for high-power CW lasers and pulsed laser systems where thermal stability and damage threshold are critical. Fused silica's ultra-low coefficient of thermal expansion (0.55 × 10⁻⁶/K) ensures excellent performance under high thermal load.

Q: How much improvement does the AR coating provide compared to uncoated glass?

A: The improvement is substantial. Our broadband AR coating achieves <0.1% reflection at each of the three optimized wavelengths (532nm, 650nm, and 1064nm). This results in transmission > 99.9% at these bands.

For comparison, uncoated glass (two surfaces) reflects approximately 8% of incident light (about 4% per surface), resulting in transmission of only ~92%. This means:

Coated window: 99.9% of your laser power passes through

Uncoated window: 8% of your laser power is lost to reflection, and the reflected light can create ghost beams that may damage other optics or interfere with system performance

For a 100W laser, the difference is 99.9W transmitted vs. only 92W transmitted — a 7.9W loss that also generates unwanted heat in the window.

Q: How does an AR coated optical window function in a laser system?

A: The optical window operates in four simple steps:

Step 1: Seal & Protect — The window is mounted as a barrier between the laser source and the external environment. It effectively blocks dust, spatter, moisture, and other contaminants from reaching sensitive internal optics, extending the lifetime of expensive laser components.

Step 2: 100% Straight Through — Unlike lenses or prisms, an optical window has parallel planar surfaces. This design ensures zero beam deviation — the laser beam passes through without changing direction, focus, or divergence angle. What enters at 0° exits at 0°.

Step 3: T > 99.9% — The broadband AR coating eliminates virtually all Fresnel reflection losses at the air-glass interfaces. Instead of losing 4% per surface (8% total), less than 0.1% per surface is reflected. More than 99.9% of the incident laser power is transmitted through the window.

Step 4: Easy Replacement — The window is designed as a consumable protective element. When the window becomes contaminated or damaged over time, it is easily replaced without disturbing or replacing the expensive internal optics. This sacrificial protection approach significantly reduces overall system maintenance costs and downtime.

Sales Engineer: Grace Gao

Email: grace@rsnv.cn

WhatsApp: +86 199 2997 5286

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