MidOpt DB Series Filter DB660/850

Salient Features

 Dual Bandpass Red  + 850nm NIR

 

DB660/850 Dual Bandpass Filter Visible Red + NIR

• Useful Range : 645-675nm, 830-870nm
• FWHM : 40nm, 55nm
• Tolerance : +/-5
• Minimum Peak Transmission : ≥90%
• Surface Quality : 40/20

The performance of a filter is based on what happens to light passing through the filter. The apparent color of light reflected off the surface is not a reliable way to judge the filter’s capabilities. Batch-to-batch difference in the apparent color of the coatings or filter substrates can often be easily seen when looking at two examples of the same filter type. The color of the coating does not indicate a disparity in performance.

 

The DB660/850 filter has been designed primarily for NDVI imaging applications. When using a single camera, incorporation of this filter allows reflected red light (660nm) to be captured in the camera sensor’s red channel and reflected near- infrared light (850nm) to be captured in the sensor’s blue channel (the green channel is not used). Even when using an inexpensive consumer camera (that has first had its IR blocking filter removed), this easy separation then makes it possible to post-process the red and blue channels for NDVI by performing the calculation: NDVI = (blue – red) / (blue + red). Healthy vegetation will absorb (not reflect) red light and strongly reflect near-infrared light. Thus this information can then be used to apply a false color gradient to images to better highlight the contrast between regions of healthy vegetation vs. areas with stressed/diseased or no vegetation.