1810nm SWIR Band Pass Filter for Sensing

1810nm SWIR Band Pass Filter for Sensing   The 1.81 µm band is located within the short-wave infrared (SWIR) region, where combinations of water and hydroxyl (OH) generate measurable absorption features. When this band is used in conjunction with reference channels, it enables effective moisture and process analysis. To capture this spectral range, extended-range InGaAs sensors (1.9–2.2 µm) are typically required, as standard InGaAs arrays (0.9–1.7 µm) exhibit significant signal roll-off near this wavelength.   SWIR imaging offers advantages such as reduced sensitivity to atmospheric haze and distinctive material contrast. As with all interference filters, the angle of incidence (AOI) must be carefully controlled to prevent spectral blue-shifting and to maintain the integrity of the passband shape. Additionally, anti-reflection (AR) coatings should be specified to minimize reflection losses. An example of this methodology can be observed in MODIS-style water vapor retrievals, which ut…

Cut Off Type Glass Selective Absorption Glass Band Pass Filter