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Journal of the Optical Society of America A

Journal of the Optical Society of America A



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Early Posting

Accepted papers to appear in an upcoming issue

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Two dimensional Green's tensor for gyrotropic clusters composed of circular cylinders

  • Ara Asatryan, Lindsay Botten, Kejie Fang, Shanhui Fan, and Ross McPhedran
  • received 07/01/2014; accepted 08/25/2014; posted 09/03/2014; Doc. ID 214986
  • [full text: PDF (1729) KB)]
  • Abstract: The construction of Green's tensor for two-dimensional gyrotropic photonic clusters composed of cylinders with circular cross-sections using the semi-analytic multipole method is presented. The high efficiency and accuracy of the method is demonstrated. The developed method is applied to gyrotropic clusters which support topological chiral Hall edge states. The remarkable tolerance of chiral Hall edge modes toward substantial cluster separation is revealed. The transformation of chiral Hall edge states as the cluster separation increases is also presented. The excitation of chiral Hall edge modes for different source orientations is considered. Both gyro-electric and gyro-magnetic(ferrite) clusters are treated.

Keywords (OCIS):

  • (050.1940) Diffraction and gratings : Diffraction
  • (290.4210) Scattering : Multiple scattering
  • (050.5298) Diffraction and gratings : Photonic crystals

(LITH2014) Robust and efficient inverse mask synthesis with basis function representation

  • Xiaofei Wu, Shiyuan Liu, Wen Lv, and Edmund Lam
  • received 07/07/2014; accepted 08/18/2014; posted 09/02/2014; Doc. ID 216337
  • [full text: PDF (2683) KB)]
  • Abstract: Mask optimization is essential in the resolution scaling of optical lithography due to its strong ability to overcome the optical proximity effect. However, it often demands extensive computation in solving the nonlinear optimization problem with a large number of variables. In this paper, we use a set of basis functions to represent the mask patterns, and incorporate this representation into the mask optimization at both the nominal plane and various defocus conditions. The representation coefficients are updated due to the gradient to the coefficients, which can be easily obtained from the gradient to the pixel variables. To ease the computation of the gradient, we use an adaptive method that divides the optimization into two steps, in which a small number of kernels is used as the first step, and more kernels are used for fine optimization. Simulations performed on two test patterns demonstrate that this method can improve the optimization efficiency by several times, and the optimized patterns have better manufacturability compared with regular pixel-based representation.

Keywords (OCIS):

  • (110.5220) Imaging systems : Photolithography
  • (110.1758) Imaging systems : Computational imaging
  • (110.4235) Imaging systems : Nanolithography

Radiologist Experience Effects on Contrast Detection

  • David Leong, Louise Rainford, Tamara Haygood, Gary Whitman, William Geiser, Tanya Stephens, Paul Davis, and Patrick Brennan
  • received 02/12/2014; accepted 08/10/2014; posted 09/05/2014; Doc. ID 206197
  • [full text: PDF (1141) KB)]
  • Abstract: Current literature shows that reader experience does not affect detection tasks, when the object does not require medical training to detect. However the research was never sufficiently detailed to examine if the contrast detection threshold is also the same for radiologists versus non-radiologists. Previously contrast threshold research was performed predominantly on non-radiologists, therefore any differences could lead to over- or under-estimation of the performance capabilities of radiologists. Fourteen readers, evenly divided between radiologists and non-radiologists, read a set of 150 mammogram-like images. The study was performed with the location of the objects known and unknown, requiring two separate readings. No difference in the contrast detection threshold between reader groups for either the location-unknown (+3) or location-known (+2) images was seen. The standard deviation for the location-unknown condition had no difference (p 0.91). But for the location-known condition, a significant difference (p 0.0009) was seen between radiologists and non-radiologists. No difference in contrast detection based on reader experience was observed, but decreased variance was seen with radiologists in the location-known condition.

Keywords (OCIS):

  • (120.2040) Instrumentation, measurement, and metrology : Displays
  • (330.1800) Vision, color, and visual optics : Vision - contrast sensitivity
  • (330.1880) Vision, color, and visual optics : Detection
  • (330.7310) Vision, color, and visual optics : Vision


(CV) Independence and interaction of luminance and chromatic contributions to spatial hyperacuity performance

  • Bonnie Cooper and Barry Lee
  • received 09/30/2013; accepted 02/02/2014; posted 02/03/2014; Doc. ID 198653
  • [full text: PDF (1336) KB)]
  • Abstract: Here we test interactions of luminance and chromatic input to spatial hyperacuity mechanisms. First, we tested alignment with matching or mismatching (contrast polarity or modality) grating pairs that were adjusted to detection threshold. Thresholds with mismatched pairs were significantly elevated. Second, we determined alignment acuity as a function of luminance or chromatic contrast alone or in the presence of contrast pedestals. For in-phase pedestal conditions, performance followed the envelope of the more sensitive mechanism. However, polarity reversals revealed an asymmetric effect for luminance and chromatic conditions. This suggests that luminance can overrule chromatic mechanisms in hyperacuity; we interpret these findings in the context of spatial mechanisms.

Keywords (OCIS):

  • (330.1720) Vision, color, and visual optics : Color vision
  • (330.5510) Vision, color, and visual optics : Psychophysics
  • (330.6100) Vision, color, and visual optics : Spatial discrimination

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