Phase Unwrapping

[sreekanth]

Hello

        Does anyone know how to perform phase unwrapping in LabVIEW.  

 

[ThomasGutzler]

There is no one way to do phase unwrapping. The method depends on the source of your signal and the measurement method.

 

It could be as simple as this, which I hacked together in a few minutes:

unwrap.vi

Edited September 12, 2014 by ThomasGutzler

[ShaunR]

Hello

        Does anyone know how to perform phase unwrapping in LabVIEW.  

 

Unwrap Phase VI

[sreekanth]

 Thank you both!!!

So for unwrapping the phase part of complex image I have to covert it into 2D array right.

[ThomasGutzler]

From your recent posts I get the impression that you're working with a digital (Fourier) holography system.

Do you, by any chance, work at a university which provides you free access to libraries and scientific journals of your area?

In that case, I'd recommend having a look at

Books:

- Introduction to Fourier Optics

- Digital Holography

Related Journal Articles by

- Schnars and Jueptner

- Depeursinge (The dude, who commercialised the holographic microscope)

- or anything else that looks remotely interesting in the area of quantitative phase unwrapping in digital holography

 

Long story short, phase unwrapping can act on the phase of a complex image, so you need to extract that first. However, the amplitude information may provide some additional information you might be able to use to guide the phase unwrapping algorithm to perform better.

[sreekanth]

You are right Thomas. I am working on digital holography.Thanks for the references.

for phase extraction I have multiplied the phase factor to the Fourier transform of the hologram(Fresnel Integral) and phase is calculated using 'IMAQ complex plane to image ' module . I had attached the extracted phase. I had doubt that what I got is not correct. Can you please check it.

 

Thanks for your support

[Gary Rubin]

If I stare at that picture with my eyes slightly crossed, should I expect to see a horse or something?

[ThomasGutzler]

You are right Thomas. I am working on digital holography.Thanks for the references.

for phase extraction I have multiplied the phase factor to the Fourier transform of the hologram(Fresnel Integral) and phase is calculated using 'IMAQ complex plane to image ' module . I had attached the extracted phase. I had doubt that what I got is not correct. Can you please check it.

 

Thanks for your support

 

I'm sorry, I'm unfamiliar with the IMAQ library.

Also, without knowledge about your optical setup and your imaging sample, it's impossible to check if your result is correct - other than confirming that what you have is a 2D array (tick).

[sreekanth]

I am using an off-axis holographic system for recording. Reconstruction is performed via Fresnel Integral. The sample is a rectangular metal sheet (6x2) with a clip attached.

Can you just post a VI showing how to extract phase from an image (in my case a hologram) without IMAQ.