Lock In Amplifier: Understand & Grasp the Idea

[sunshine111]

hi,
I am interested to know how the lock in amplifier works?
It is very commonly seen with oscilloscope, but I fail to grasp the idea behind it?
I would appreciate any lecture notes or sites which give clear and precise understanding of it.


Thanks

 

[mgb_phys]

The principle of why it works/is used or the details of how the internal circuits achieve this?

There is a good tutorial linked to form the wiki article http://www.bentham.co.uk/pdf/F225.pdf