What sensor can be used to find out the depth of the extension of the lock bolt?

Question

Arduino

I want to check which lock in the front door is closed and how many turns. How can this be done with output to Adruino or RaspberryPi? Installing any things is complicated by the fact that the door frame is iron.

Answer 1

For example, like this:
Blacken the locking cavity, leave the end of the crossbar light.
At the bottom of the locking cavity, fix the optocoupler for reflection.

Answer 2

If the lock has 3 possible bolt positions - 2 optocouplers.

Answer 3

Stick a magnet on the bolt, put the Hall sensor in the locking cavity.

Answer 4

I want to adapt the TCRT5000L for this - I played with it on the table, it detects a few centimeters normally.

Answer 5

Two or three mics or a couple of coils.