scanning electrometer

one of my first attempts at building a 'scanning electrometer'.

one of my first attempts at building a ‘scanning electrometer’.

At the moment I am working to improve a rather elementary sensor for electrostatic fields, in an attempt to use it to make images. Since I do not really know what these images should look like, that brought me to an interesting and unexpected philosophical question today:

how do we know that a sensor that scans the environment is picking up more than artefacts of its own scanning motion ?

a primitive scanning setup.

a primitive scanning setup.

UPDATE: turning the scanning device upside down also turns the main gradient in the image upside down, so we do have some sort of signal ?
There is some way to go to make this do anything, however..

a scan with the scanner upside down.

a scan with the scanner upside down.