Dispersive optical phased array circuit for high-resolution pixelated 2D far-field scanning controlled by a single wavelength variable

Two main problems in high resolution electron microscopy are first, the existence of gaps in the transfer function, and then the difficulty to find complex amplitude of the diffracted wawe from registered intensity. The solution of this second problem is in most cases only intended by the realization of several micrographs in different conditions (defocusing distance, illuminating angle, complementary objective apertures…) which can lead to severe problems of contamination or radiation damage for certain specimens.Fraunhofer holography can in principle solve both problems stated above (1,2). The microscope objective is strongly defocused (far-field region) so that the two diffracted beams do not interfere. The ideal transfer function after reconstruction is then unity and the twin image do not overlap on the reconstructed one.We show some applications of the method and results of preliminary tests.Possible application to the study of cavitiesSmall voids (or gas-filled bubbles) created by irradiation in crystalline materials can be observed near the Scherzer focus, but it is then difficult to extract other informations than the approximated size.

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An Optimized Scheme for Optical Phased Array Beam Steering Controlled by Wavelength

PIERS Online ◽

10.2529/piers060906093853 ◽

2007 ◽

Vol 3 (2) ◽

pp. 127-131 ◽

Cited By ~ 3

Author(s):

Ying Zhao ◽

Xiaozhou Yang ◽

Qin Cai ◽

Weiwei Hu

Keyword(s):

Phased Array ◽

Beam Steering ◽

Optical Phased Array

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Three Dimensionally Interconnected Silicon Nanomembranes for Optical Phased Array (OPA) and Optical True Time Delay (TTD) Applications

10.21236/ada567453 ◽

2012 ◽

Author(s):

Ray T. Chen

Keyword(s):

Time Delay ◽

Phased Array ◽

True Time Delay ◽

Silicon Nanomembranes ◽

Optical Phased Array ◽

True Time

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A Design Approach of Optical Phased Array with Low Side Lobe Level and Wide Angle Steering Range

Photonics ◽

10.3390/photonics8030063 ◽

2021 ◽

Vol 8 (3) ◽

pp. 63

Author(s):

Xinyu He ◽

Tao Dong ◽

Jingwen He ◽

Yue Xu

Keyword(s):

Phased Array ◽

Phase Distribution ◽

Beam Steering ◽

Side Lobe ◽

Design Approach ◽

Optical Antennas ◽

Side Lobe Level ◽

Wide Angle ◽

Spacing Distribution ◽

Optical Phased Array

In this paper, a new design approach of optical phased array (OPA) with low side lobe level (SLL) and wide angle steering range is proposed. This approach consists of two steps. Firstly, a nonuniform antenna array is designed by optimizing the antenna spacing distribution with particle swarm optimization (PSO). Secondly, on the basis of the optimized antenna spacing distribution, PSO is further used to optimize the phase distribution of the optical antennas when the beam steers for realizing lower SLL. Based on the approach we mentioned, we design a nonuniform OPA which has 1024 optical antennas to achieve the steering range of ±60°. When the beam steering angle is 0°, 20°, 30°, 45° and 60°, the SLL obtained by optimizing phase distribution is −21.35, −18.79, −17.91, −18.46 and −18.51 dB, respectively. This kind of OPA with low SLL and wide angle steering range has broad application prospects in laser communication and lidar system.

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