65-185 25 mm Dia. Hard Coated OD 4.0 10nm Bandpass Filter; t=3.5 mm 940nm

The 65-185 is a Bandpass Filter with a diameter of 25 mm, sourced from the renowned optical components vendor, Edmund Optics. This filter is specifically designed for a central wavelength (CWL) of 940nm, making it an ideal choice for applications that require narrowband transmission in this spectral region.

The filter is hard coated with a durable coating, identified as EDM 65-124, on both the front and back surfaces. This coating enhances the filter's durability and resistance to environmental factors, ensuring reliable performance over time.

The filter's geometry is defined by a diameter of 25 mm and a thickness of 3.5 mm. The 'OD 4.0' in the product name refers to the filter's optical density, which is a measure of its ability to attenuate light at specified wavelengths. In this case, the optical density of 4.0 indicates a high level of attenuation outside the passband.

The passband of the filter is defined by the 'cut on' and 'cut off' wavelengths, which are 935nm and 945nm, respectively. This 10nm bandpass ensures a high level of transmission within the passband while effectively blocking light outside this range.

The filter is designed in the shape of a thin lens, which can be beneficial in certain optical systems where space is a constraint. The filter's 'Thin Lens' shape also allows for easy integration into existing optical designs.