Is it possible to transfer a low amplitude DC signal from the input to output by using an Optoisolator? I mean, Is the output a function of the input or a switching signal according to input? If yes what kind of Optoisolator can I use to isolate my low amplitude DC signal?

 

Optoisolators can be considered analog devices, thus the output is a function of the input. There are many in the market, if you make a search in google you will find many and you have to choose one depending on your needs.

 

Optoisolators are mainly for digital data. The IRLED wants 30 - 50 ma to drive, and the output is usually an open collector phototransistor or logic compatible.

Could you give some data - how low is low amplitude, and why it needs isolation?

 

It depends on the levels. A linear optocoupler, like the Vishay IL300, may work.

You may be better off looking for isolation amplifiers. Checkout TI and Analog Devices.

(* jcl *)

 

it should be isolated because the signal have high potential according to ground and I need to measure this mV Dc signal. I already checked isolation amplifiers but for example iso122 and iso124, it is really hard find them in europe all of the stocks are ran out. What I can easy find is, HCPL optoisolator at the moment.

 

IIRC the HCPL are digital devices.

Measuring a mV signal through a linear optocoupler will be difficult.
A pre-amp + IL300 could work.

A pre-amp + A/D converter on the signal side would work. Use the optocoupler
on the A/D digital lines.

(* jcl *)