86-661 25 mm Dia. Hard Coated OD 4.0 25nm Bandpass Filter; t=3.5 mm 850nm

The 86-661 is a Bandpass Filter with a diameter of 25 mm, manufactured by Edmund Optics. This filter is designed for use with a central wavelength of 850 nm, making it suitable for applications that require precise wavelength selection in this range.

The filter features a hard coating on both the front and back surfaces, denoted as 'edm 86-649'. This coating enhances the durability and longevity of the filter, making it resistant to scratches and other forms of damage. The coating also aids in maintaining the filter's performance over time.

The physical dimensions of the filter include a diameter of 25 mm and a thickness of 3.5 mm. This thickness allows for efficient integration into optical systems while maintaining a compact footprint. The filter's geometry is defined as a 'Thin Lens', suggesting that it may have some light-bending properties.

The filter's spectral properties are defined by its 'cut on' and 'cut off' wavelengths, which are 837.5 nm and 862.5 nm, respectively. These values represent the wavelengths at which the filter begins and ends its transmission. The 'cwl' or 'center wavelength' is 850 nm, indicating the wavelength at which the filter's transmission is at its maximum.

The filter is currently in stock and available for purchase through the provided weblink.