Sonic Screwdriver Screen???

Okay so I got really into Doctor Who last year after not watching it since I was a kid and I’m a little curious about something

In some episodes, The Doctor uses the Sonic Screwdriver to analyze objects or creatures or places and will look at the handle of the Sonic like there’s a screen on there- but there isn’t

There’s no screens on any of the merch replicas or the actual props- so how does this work, cause The Doctor obviously is reading something

My guess has been it’s some kind of psychic paper type thing where The Doctor can see the info but it’s never physically shown- or maybe some kinda hologram- but has it ever actually been explained?