Designed for use in aerial crop monitoring, the Bi725 Red Edge Bandpass Filter is a 25nm FWHM filter which isolates the wavelength region where the most rapid change in reflectance occurs in foliage. This occurs when plants are stressed or dying, and the photosynthesis slows down or stops. IR wavelengths are absorbed, whilst more visible light, particularly red light, is reflected. The transitional 725nm band is uniquely affected by vegetative health changes and provides information relating to chlorophyll and nitrogen status used to distinguish thriving from stressed vegetation.
Healthy vegetation will absorb (not reflect) green light and strongly reflect near-infrared light. So the DB550/850, when modifying a single colour camera by removing its IR blocking filter, allows reflected near-infrared light (850nm) to be captured in the camera sensor’s red channel and reflected green light (550nm) to be captured in the sensor’s green channel (the blue channel is not used). This information can then be used to apply a false colour gradient to images to better highlight the contrast between regions of healthy vegetation as opposed to areas with stressed, diseased, or no vegetation.
For more information on these specialist filters, please contact our dedicated sales team.