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Adaptive optimisation of a generalised phase contrast beam shaping system.

Kenny F, Choi FS, Glückstad J, Booth MJ - Opt Commun (2015)

Bottom Line: This provided extra flexibility and control over the parameters of the system including the phase step magnitude, shape, radius and position of the filter.A feedback method for the on-line optimisation of these properties was also developed.Using feedback from images of the generated light field, it was possible to dynamically adjust the phase filter parameters to provide optimum contrast.

View Article: PubMed Central - PubMed

Affiliation: Centre for Neural Circuits and Behaviour, University of Oxford, Mansfield Road, Oxford OX1 3SR, United Kingdom.

ABSTRACT

The generalised phase contrast (GPC) method provides versatile and efficient light shaping for a range of applications. We have implemented a generalised phase contrast system that used two passes on a single spatial light modulator (SLM). Both the pupil phase distribution and the phase contrast filter were generated by the SLM. This provided extra flexibility and control over the parameters of the system including the phase step magnitude, shape, radius and position of the filter. A feedback method for the on-line optimisation of these properties was also developed. Using feedback from images of the generated light field, it was possible to dynamically adjust the phase filter parameters to provide optimum contrast.

No MeSH data available.


GPC images of a circle shown for different diameters of phase contrast filters, increasing from left to right. The PCF for the left image has no PCF present; there is little difference in intensity between pixels inside and outside the circle. The PCF for the central image has a more optimal diameter of 8 SLM pixels (pixel size=15 μm), while the PCF for the right image is larger than optimal at 16 pixels.
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f0025: GPC images of a circle shown for different diameters of phase contrast filters, increasing from left to right. The PCF for the left image has no PCF present; there is little difference in intensity between pixels inside and outside the circle. The PCF for the central image has a more optimal diameter of 8 SLM pixels (pixel size=15 μm), while the PCF for the right image is larger than optimal at 16 pixels.

Mentions: Using the circular phase pattern, the optimal diameter for the filter was found to be 9 pixels, which was equivalent to 135 μm as the pixel size of the SLM was 15 μm. This metric curve, depicted in Fig. 4(a) showed a clear peak indicating the optimal filter diameter for this pattern. Plotting a similar curve for the second input phase distribution gave a different value for the optimal filter diameter. The optimal filter diameter for the line pattern was 10 pixels, equivalent to 150 μm. The metric curve for this measurement is shown in Fig. 4(b). Example images from this experiment are also shown in Fig. 5. This figure shows the GPC image obtained using the circle pattern for different diameters of phase contrast filter. These qualitatively show a variation in the contrast of the output when the diameter of the PCF is changed.


Adaptive optimisation of a generalised phase contrast beam shaping system.

Kenny F, Choi FS, Glückstad J, Booth MJ - Opt Commun (2015)

GPC images of a circle shown for different diameters of phase contrast filters, increasing from left to right. The PCF for the left image has no PCF present; there is little difference in intensity between pixels inside and outside the circle. The PCF for the central image has a more optimal diameter of 8 SLM pixels (pixel size=15 μm), while the PCF for the right image is larger than optimal at 16 pixels.
© Copyright Policy - CC BY
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4459477&req=5

f0025: GPC images of a circle shown for different diameters of phase contrast filters, increasing from left to right. The PCF for the left image has no PCF present; there is little difference in intensity between pixels inside and outside the circle. The PCF for the central image has a more optimal diameter of 8 SLM pixels (pixel size=15 μm), while the PCF for the right image is larger than optimal at 16 pixels.
Mentions: Using the circular phase pattern, the optimal diameter for the filter was found to be 9 pixels, which was equivalent to 135 μm as the pixel size of the SLM was 15 μm. This metric curve, depicted in Fig. 4(a) showed a clear peak indicating the optimal filter diameter for this pattern. Plotting a similar curve for the second input phase distribution gave a different value for the optimal filter diameter. The optimal filter diameter for the line pattern was 10 pixels, equivalent to 150 μm. The metric curve for this measurement is shown in Fig. 4(b). Example images from this experiment are also shown in Fig. 5. This figure shows the GPC image obtained using the circle pattern for different diameters of phase contrast filter. These qualitatively show a variation in the contrast of the output when the diameter of the PCF is changed.

Bottom Line: This provided extra flexibility and control over the parameters of the system including the phase step magnitude, shape, radius and position of the filter.A feedback method for the on-line optimisation of these properties was also developed.Using feedback from images of the generated light field, it was possible to dynamically adjust the phase filter parameters to provide optimum contrast.

View Article: PubMed Central - PubMed

Affiliation: Centre for Neural Circuits and Behaviour, University of Oxford, Mansfield Road, Oxford OX1 3SR, United Kingdom.

ABSTRACT

The generalised phase contrast (GPC) method provides versatile and efficient light shaping for a range of applications. We have implemented a generalised phase contrast system that used two passes on a single spatial light modulator (SLM). Both the pupil phase distribution and the phase contrast filter were generated by the SLM. This provided extra flexibility and control over the parameters of the system including the phase step magnitude, shape, radius and position of the filter. A feedback method for the on-line optimisation of these properties was also developed. Using feedback from images of the generated light field, it was possible to dynamically adjust the phase filter parameters to provide optimum contrast.

No MeSH data available.