Should I choose a filter?


Carnegie Robotics offers there filter options; visible (400-700 nm), wide (400-1100 nm), and visible with IR bandpass (400-700 nm and 830-870nm).

It is unlikely that there is any added benefit from a filter when using a mono imager. The filter choice is most critical when coupled with a color imager. Color filters all have a similar response to IR light above 800 nm, which means that IR light entering the imager will wash out the colors. Indoor images may appear clear because indoor lighting has limited IR, but outdoor images may wash out severely. A lot of the colors will look lighter than they should since all pixels are being activated equally by IR light, making them appear white.

The solution to this is to use the visible light filter, which will prevent light above 700 nm from entering the imagers. This will correct the color, but it will make it impossible to use any additional IR lighting, such as our pattern projector add-on.

Our IR pattern projector add-on produces a wavelength of ~850 nm. The appropriate filter when coupling a camera with a pattern projector is to use the visible light filter with bandpass. This will allow the appropriate band of IR light into the imagers that alight with the pattern projector’s wavelength.

When using an IR enhanced imager, it is unlikely that any of our filters will be appropriate since the purpose of the IR enhanced imager is to achieve an increased response. Adding a filter will only reduce the amount of light that enters the sensor. 

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