FB1550-12 In Stock

The ThorLabs FB1550-12 is a top-of-the-line Ø1" bandpass filter that provides a highly effective and easy-to-use solution that rejects radiation that is unwanted while also transmitting a band of light that has a well-defined wavelength. Additionally, the FB1550-12 has a center wavelength of 1550 nm and a 12 nm bandpass region.

In the bandpass region, the FB1550-12 boasts very high transmission, however on either side of the bandpass region, the blocked light spectral range is narrow. In order to counterbalance this result, another blocking component can be added, which can be either an metal-dielectric or all dielectric based on the filter's requirements. This component effectively eliminates any unwanted out-of-band radiation, but it does reduce the FB1550-12's overall transmission throughput.

The FB1550-12's design is based on a thin film Fabry-Perot interferometer, which is created through techniques of vacuum deposition. The filter consists of two stacks that reflecting and are kept separate by an even-order spacer layer, with alternating layers of high and low refractive index materials. This design ensures a reflectance of up to 99.99%, and the central wavelength and bandwidth of the filter can be easily adjusted through changing the amount of reflecting layers and/or the spacer layer thickness. It is important to note that due to the Fabry-Perot design, the FB1550-12 is designed for use at a 0° angle of incidence (AOI). Using other AOIs may result in a shift in wavelength and reduction in transmission band.

The FB1550-12 comes housed in a anodized ring that is black, fabricated from aluminum, and has a arrow that clearly indicates the direction of design propagation. The ring limits scattering which enhances the blocking OD and makes handling of the filter easier. The FB1550-12 is highly versatile and can be mounted into a variety of filter mounts and wheels. However, it is important to note that a retaining ring is required to mount the filter into internally-threaded lens tubes. It is also recommended not to remove the filter from its mount, because the filter has a mounting ring and epoxy that hold several layers of glass together. These layers protect the dielectric coating from exposure to the atmosphere, which could significantly reduce the filter's transmission efficiency over time.