Midwest Optical Systems, Inc. products

The BP250 Near-UV Bandpass Filter for Machine Vision is a very broadband UV filter, mainly intended for deep-UV imaging. It is the only MidOpt UV filter available that offers excellent visible and near-IR blocking (≤0.1% abs. ≥400nm; ≤0.06% abs. ≥415nm), thus making it best suited to distinguish features or characteristics that are only visible under UV illumination. Offered in a limited number of sizes, and not intended for use with standard CCD/CMOS cameras that do not image deep into the UV spectrum.

The DB475/850 Dual Bandpass Filter has been primarily designed for NDVI imaging applications. When using a single camera, incorporation of this filter allows reflected near-infrared light (850nm) to be captured in the camera sensor’s red channel and reflected blue light (475nm) 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 = (red – blue) / (red + blue). Healthy vegetation will absorb (not reflect) blue 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.