Do you have a spectrum analyser? If not then fft may be the answer if you have it as a function on your scope.

If you use a programmable function generator to generate the sweep signal, it may be a good idea to develop a LabView code to command the FG and collect the signal from LDV. The frequency value will be the same as the excitation frequency.

What model and company of laser vibrometer are you using? If using Polytec their acquisition software should be able to do this for you. Using a sweep for the desired range of frequencies, you will see the oscilloscope depending what you want: X-axis: frequency (bandwidth) and Y-axis: Magnitud (velocity). You can extract the data and process it in Origin.

Thanks for your helpful information.

Mr. Carreno: I am using Polytec OFV 3001. Unfortunately, I don't have their acquisition software. Is their any other way to get frequency values? 

Hello Suma,

The best way I could think of would be to create an interface using NI Labview. You will need the diver for the Polytec OFV 3001. It might be pretty straight forward for initial testing and then you will have to customize as you need.

This is the link to the Labview Driver for the OFV 3001: http://sine.ni.com/apps/utf8/niid_web_display.model_page?p_model_id=7506

Hope this helps. Good Luck.

Kind Regards,

Arpys

Thanks a lot Carreno.

I have installed Labview and started working on it. I got stuck with a connection between Oscilloscope and PC. I am using LeCroy waverunner 204xi. I couldn't find the right cable to connect both oscilloscope and PC. So, I decided to use another oscilloscope, LeCroy waverunner LT344 and connected with NI GPIB connector to PC. Unfortunately, I couldn't find the driver of it. 

I really appreciate your help.