A very accurate frequency demodulator

[vir]

I am working on a biomedical engineering research project. It involves investigating the possible techniques of measuring mean light pathways variations of the light propagating through a vascular tissue.

One of the theoretically predicted ways of conducting such a measurement requires a very accurate frequency demodulator.

The predicted signal frequency modulation ranges are as following:
- f = 500 MHz, Δf = 5 μHz
- f = 1 GHz, Δf = 10 μHz
- f = 10 GHz, Δf = 100 μHz
- … (and so on – the relation is linear)
f is the base harmonic signal frequency, Δf is the expected frequency modulation range (μ - micro).

I have zero experience in both high frequency and FM techniques.
Can you advise please if it is at all possible, what devices/techniques might be used to demodulate the described above signal.

Thank you,

Victor.

[Ben.h]

Hi Victor

I think the answer to your question is dependant on budget, time and what equipment you already have. I think it would be benficial for you to call NI and speak to Field Sales Engineer.

The telephone number for the NI UK branch is

01635 523 545

Kind Regards

Ben Hartrick

Applications Engineer

NIUK Tech Support

[Henrik_Volkers]

Might be a bit late :), but how about interferometrie with the frequency of light (THz)?

[vir]

Henrik, thank you for the advice - good ideas are never too late.

I came to the same conclusion: laser light + interferometer + beating should do the job.

Victor.

[Henrik_Volkers]

We use homodyne laser interferometer here. That allow us to measure changes in distances in fractions of the laser wavelength.

One good (major) adress is Polytec, if you don't want to mess around with the optics by yourself.

[Henrik_Volkers]

Short correction: replace homodyne with heterodyne... 🙂

and here is the link to Polytec

http://www.polytec.com