85-898 25 mm Dia. Hard Coated OD 4.0 50nm Bandpass Filter; t=3.5 mm 1300nm

The 85-898 is a Bandpass Filter with a diameter of 25 mm, sourced from the renowned optical components vendor, Edmund Optics. This particular filter is designed to transmit light within a specific range of wavelengths, centered around 1300nm, making it ideal for applications that require narrow-band light transmission.

The filter is hard coated with a refractive index of 4.0, ensuring durability and resistance to wear and tear. It features a thickness of 3.5 mm, providing sufficient structural integrity for most applications. The filter's geometry is designed in a circular shape, which is a common choice due to its uniform light transmission and ease of integration into various optical systems.

The 85-898 filter's physical data includes a cut-on wavelength of 1275nm and a cut-off wavelength of 1325nm. This means that it begins to transmit light at 1275nm and stops transmitting at 1325nm, effectively filtering out light outside this range. The central wavelength (CWL) of this filter is 1300nm, indicating the midpoint of the transmission range.

The filter's coating is uniformly applied on both the front and back surfaces. It uses the EDM 85-886 coating, which is a hard coating known for its durability and excellent optical properties. This coating enhances the filter's performance and longevity, making it a reliable choice for various optical applications.

The shape of the 85-898 filter is that of a Thin Lens, which is a type of optical element that focuses or disperses light. This shape allows the filter to be used not only as a wavelength-selective element but also as a lens, providing additional functionality and versatility.