Optical bandpass filters are used to fine-tune the bandwidth of the sensor, as most sensors actually have pretty wide bandwidths. Typical silicon sensors have sensitivity extending well into the IR, which can confuse people when their pictures show lights they can't see. This can totally be made using something like the dark-red filter on the TV remote (reversed, it'd block red so appear blue), but fancier ones will use thin-film coatings to achieve steeper roll-offs. I don't see how meta-lenses are supposed to achieve this effect. They may use absorbing substrate, or may add a backside coating.

Contact image sensors are image sensors designed to be slapped right up against something. They're used in scanners and surface inspection sensors. No clue how this relates to meta-lenses.

I suspect it's just a bad diagram. Their barrel design is impossible to manufacture.

Source: Optical engineer.

https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=10...

https://en.wikipedia.org/wiki/Contact_image_sensor