FEL1050 In Stock

The FEL1050 by ThorLabs is a premium soft-coated longpass filter that offers exceptional spectral isolation for a range of applications, including astronomy. Designed with a durable dielectric coating, the FEL1050 can withstand regular cleaning and handling required for high-quality optical components.

The FEL1050 utilizes a film construction that incorporates a modified quarter-wave stack, which employs interference effects instead of absorption to isolate spectral bands. Unlike colored filter glass, the FEL1050 cut-on wavelength shifts to a shorter wavelength as the angle of incidence is increased. This feature allows for precise fine-tuning of the cut-on wavelength in applications where it is necessary.

The FEL1050 is enclosed in a black anodized aluminum construction, labeled with an arrow which points in the direction of propagation to make it easily to handle and also reduce the OD path-length by limiting scattering. The FEL1050 is compatible with a variety of filter mounts and wheels and can be mounted using a Ø1" retaining ring into an internally-threaded SM1 lens tube. However, it is highly advised not to take the filter out of its mount since it comprises of several glass pieces bonded together by epoxy and the mounting ring. The layers shielding the dielectric covering from any outer environment ensure the filter has a better transmission rate an efficiency overtime. Exposure could result in the deterioration of the filter’s performance.