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 FFT for Terahertz Time Domain Signal		  New Topic  Reply to Topic
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JannieT

Singapore
7 Posts
Posted - 02/05/2018 :  09:00:16 AM  Show Profile  Edit Topic  Reply with Quote  View user's IP address  Delete Topic
Origin Ver. and Service Release (Select Help-->About Origin):
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Hi,

Seems like some of the ORIGIN Lab users have some experience with Terahertz Time Domain Spectroscopy (THz-TDS). Therefore, I would like to try asking about use of OriginLab for THz-TDS for reflection mode.


I have 2 time domain signals for polymers characterized by reflection THz-TDS- sample and reference. The time is recorded in terms of ps.

I am trying to obtain n and k of complex refractive index for the polymer via the following formulas.




I have done FFT on the time domain signals. But not sure if I have done correctly. I have tried to set +1 and -1 for factor, but to no avail. As phase value also comes into play for calculation for n and k, should the unwrap phase box be unchecked too?








Or did I make some mistake?

Can someone kindly give me some advice. Any help will be deeply appreciated. Thank you!

Sam Fang

292 Posts
Posted - 02/06/2018 :  03:31:46 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
It doesn't matter whether unwrap phase box is checked or not.

But Origin's phase is degree unit instead of radian. In your column G, you should convert it to radian unit, i.e. col(G)=(col(E)-col(D))/180*pi

Sam
OriginLab Technical Services
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JannieT

Singapore
7 Posts
Posted - 02/07/2018 :  03:16:53 AM  Show Profile  Edit Reply  Reply with Quote  View user's IP address  Delete Reply
It works, thank you!
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