Featured Glass/ mirror portrait brooch, please help!

Good afternoon,
Came across this brooch, I find it very ingenious how it was made. The portrait disappears and it only remains a shadow when moved. I wonder what is this technique called, how old is it? Is the man in the picture someone we might know?
Is that a mirror at the back, where the portrait is engraved/printed?
Looks to me as nowadays laser techniques, it’s just amazing to see that something similar, with no technology was done many years ago, don’t you think?
Thank you.
Kind regards,
Simona
P.S. This was not an expensive item, but very interesting.

 

Oh! A daguerréotype !!!
https://en.m.wikipedia.org/wiki/Daguerreotype

 

I wouldn't say "no technology"! Daguerreotypes were cutting edge tech that blew everyone away! Started a craze that developed new methods. Changed the way we saw and documented things forever.

They are highly collectable. What a great find!

 

Thank you so much, it’s fascinating, the materials, the process… I have enjoyed learning something new, really appreciate it.