Pixel size unit

Hi,

I found the following code in our bliss-tomo project (https://gitlab.esrf.fr/tomo/ebs-tomo)

ccd_ps = det.proxy.camera_pixelsize[0]
# Frelon return pixel size in meters, PCO and Andor in um!
if det.camera_type.lower() == "frelon":
    # conversion in microns
    ccd_ps *= 1e6

I think it would be good to normalize that in order to reduce such tuning.

The best thing would be to normalize the Lima implementation and use the same unit everywhere, but i am afraid it could break stuffs in beamlines.

So one of the idea could be to provide a new function in the lima tango device.

def camera_pixelsize_um(...):
    """Returns the camera pixel size in micrometer"""

Such function could contain the fix according to each detector.

What do you think?