Limits...
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.


The recorded optical image of the USAF test target with different applied voltages which corresponds to (a) Δn = 0, (b) Δn = 0.0011, (c) Δn = 0.011, (d) Δn = 0.0915, (e) Δn = 0.184 and (f) Δn = 0.205.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5384217&req=5

f5: The recorded optical image of the USAF test target with different applied voltages which corresponds to (a) Δn = 0, (b) Δn = 0.0011, (c) Δn = 0.011, (d) Δn = 0.0915, (e) Δn = 0.184 and (f) Δn = 0.205.

Mentions: Figure 5 presents the optical image with different applied voltages where the groups 6 and 7 of the USAF target are directly imaged onto the CCD camera. These optical images are approximately the same as the applied voltage is varied mainly due to the small refractive index variation. The smallest lines are in the group 7, element 6 with a line width of 2.19 μm. Furthermore, it shows this target is roughly magnified 100 times, thus the corresponding calculated pixel pitch size is 0.06 μm. Figure 6 displays the retrieved phase images using Eq. (6) with Δn of 0.205 and the conventional TIE method with 10 μm optical path difference. As can be seen in Fig. 6, all lines in both phase images are completely resolved as a result of the Hilbert transform which provides enhanced phase changes with a large phase gradient. That is, the smallest resolvable element is group 7, element 6, defining a lateral resolution of 2.19 μm. In addition, our approach provides a better image quality with better noise suppression compared to the conventional TIE technique. There are some horizontal lines in both images because we apply one-dimensional Hilbert transform horizontally to solve the TIE equation.


Non-interferometric phase retrieval using refractive index manipulation
The recorded optical image of the USAF test target with different applied voltages which corresponds to (a) Δn = 0, (b) Δn = 0.0011, (c) Δn = 0.011, (d) Δn = 0.0915, (e) Δn = 0.184 and (f) Δn = 0.205.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f5: The recorded optical image of the USAF test target with different applied voltages which corresponds to (a) Δn = 0, (b) Δn = 0.0011, (c) Δn = 0.011, (d) Δn = 0.0915, (e) Δn = 0.184 and (f) Δn = 0.205.
Mentions: Figure 5 presents the optical image with different applied voltages where the groups 6 and 7 of the USAF target are directly imaged onto the CCD camera. These optical images are approximately the same as the applied voltage is varied mainly due to the small refractive index variation. The smallest lines are in the group 7, element 6 with a line width of 2.19 μm. Furthermore, it shows this target is roughly magnified 100 times, thus the corresponding calculated pixel pitch size is 0.06 μm. Figure 6 displays the retrieved phase images using Eq. (6) with Δn of 0.205 and the conventional TIE method with 10 μm optical path difference. As can be seen in Fig. 6, all lines in both phase images are completely resolved as a result of the Hilbert transform which provides enhanced phase changes with a large phase gradient. That is, the smallest resolvable element is group 7, element 6, defining a lateral resolution of 2.19 μm. In addition, our approach provides a better image quality with better noise suppression compared to the conventional TIE technique. There are some horizontal lines in both images because we apply one-dimensional Hilbert transform horizontally to solve the TIE equation.

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.