FL635-10 In Stock

The ThorLabs FL635-10 is a high-quality laser line filter that is designed to offer superior performance and stability for demanding applications. The filter has a center wavelength of 635 nm and is mounted in an unthreaded black anodized aluminum ring with a maximum edge thickness of 6.3 mm and an outer diameter of Ø1". The edge of the FL635-10 is scribed to enable superb long-term stability, ensuring that the filter maintains its performance over time.

The aluminum ring of the FL635-10 is labeled with an arrow that indicates the design transmission direction, making it easier to handle and enhancing the blocking OD by limiting scattering. It should be noted the optimal placing of the coated side of the filter is in the direction of the source, though the FL635-10 can function with either side facing the direction of the source. When the coated side faces the source, any potential thermal effects or thermal damage from intense out-of-band radiation blocking due to absorbing out-of-band radiation from the colored glass filter layers or substrate.

The FL635-10 can be mounted into a variety of filter mounts and wheels, making it a versatile option for a wide range of applications. It is important to note that the FL635-10 filter consists of multiple glass layers that are held together with the mounting ring and epoxy. These glass layers are imperative for the dielectric coating’s protection from the atmosphere, and the filter’s transmission efficiency will be significantly reduced over time due to exposure. Therefore, it is not recommended to remove the filter from its mount.

The FL635-10 uses a construction similar to a Fabry-Perot interferometer, which allows light at the central wavelength, and efficient transmission of a small band of wavelengths to either side of the filter, while transmission of the light outside the passband is prevented by destructive interference. However, the band of blocked wavelengths on either side of the central wavelength is small. To increase the blocking range of the filter, materials with broad blocking ranges are used for or coated onto the spacer layers and the substrate. While these materials effectively block out-of-band transmission of incident radiation, they also decrease the transmission through the FL635-10 in the passband.