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Non-interferometric phase retrieval using refractive index manipulation

View Article: PubMed Central - PubMed

ABSTRACT

We present a novel, inexpensive and non-interferometric technique to retrieve phase images by using a liquid crystal phase shifter without including any physically moving parts. First, we derive a new equation of the intensity-phase relation with respect to the change of refractive index, which is similar to the transport of the intensity equation. The equation indicates that this technique is unneeded to consider the variation of magnifications between optical images. For proof of the concept, we use a liquid crystal mixture MLC 2144 to manufacture a phase shifter and to capture the optical images in a rapid succession by electrically tuning the applied voltage of the phase shifter. Experimental results demonstrate that this technique is capable of reconstructing high-resolution phase images and to realize the thickness profile of a microlens array quantitatively.

No MeSH data available.


(a) The recorded optical image for Δn = 0 and (b) the tomography measured by the AFM of the ML array.
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f8: (a) The recorded optical image for Δn = 0 and (b) the tomography measured by the AFM of the ML array.

Mentions: Figure 8(a) and (b) show the optical image and tomography measured by the atomic force microscope (AFM) of a plano-convex microlens array, respectively. By using the aforementioned pixel pitch size, the calculated pitch of microlens array is roughly 14.31 μm, which is slightly larger than 14.04 μm obtained by AFM. In addition, we observe interference patterns in each microlens element as a result of multiple beam interference. Here, we use the TIE solver by FFT because these interference patterns might result in rippled phase images after Hilbert transform. Figure 9 reveals the retrieved phase images of the microlens array obtained by using Eq. (6) with Δn of 0.205 and the conventional TIE method. We can see that each microlens is clearly resolved without noise fluctuation. Figure 10 illustrates the resolved thickness distribution of the microlens and the tomography measured by the AFM. The resolved profiles closely agree with that measured by the AFM.


Non-interferometric phase retrieval using refractive index manipulation
(a) The recorded optical image for Δn = 0 and (b) the tomography measured by the AFM of the ML array.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5384217&req=5

f8: (a) The recorded optical image for Δn = 0 and (b) the tomography measured by the AFM of the ML array.
Mentions: Figure 8(a) and (b) show the optical image and tomography measured by the atomic force microscope (AFM) of a plano-convex microlens array, respectively. By using the aforementioned pixel pitch size, the calculated pitch of microlens array is roughly 14.31 μm, which is slightly larger than 14.04 μm obtained by AFM. In addition, we observe interference patterns in each microlens element as a result of multiple beam interference. Here, we use the TIE solver by FFT because these interference patterns might result in rippled phase images after Hilbert transform. Figure 9 reveals the retrieved phase images of the microlens array obtained by using Eq. (6) with Δn of 0.205 and the conventional TIE method. We can see that each microlens is clearly resolved without noise fluctuation. Figure 10 illustrates the resolved thickness distribution of the microlens and the tomography measured by the AFM. The resolved profiles closely agree with that measured by the AFM.

View Article: PubMed Central - PubMed

ABSTRACT

We present a novel, inexpensive and non-interferometric technique to retrieve phase images by using a liquid crystal phase shifter without including any physically moving parts. First, we derive a new equation of the intensity-phase relation with respect to the change of refractive index, which is similar to the transport of the intensity equation. The equation indicates that this technique is unneeded to consider the variation of magnifications between optical images. For proof of the concept, we use a liquid crystal mixture MLC 2144 to manufacture a phase shifter and to capture the optical images in a rapid succession by electrically tuning the applied voltage of the phase shifter. Experimental results demonstrate that this technique is capable of reconstructing high-resolution phase images and to realize the thickness profile of a microlens array quantitatively.

No MeSH data available.