Proposal for Inverse-Phase Composite Zone Plate for Deeper Depth of Focus

Previously (Chen et al., 2004), it was shown that dielectric cylinder can form focal spots with small diameters and long depth. This type of focal spot was called photonic nanojet. In this paper, it was shown that dielectric cylinder of radius 595 nm (1.12 of wavelength) forms near the surface a photonic nanojet with diameter equal to 0.31 of wavelength and depth of focus equal to 0.57 of wavelength. Adding truncated concentric rings with radiuses equal to radiuses of zone plate to the cylinder increases the depth of focus to 1.18 of the wavelength. The diameter and intensity of focal spot near the cylinder surface remain unchanged.

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Inverse-phase composite zone plate providing deeper focus than the normal diffraction-limited depth of X-ray microbeams

Journal of Synchrotron Radiation ◽

10.1107/s1600577518016703 ◽

2019 ◽

Vol 26 (1) ◽

pp. 52-58

Author(s):

Yasushi Kagoshima ◽

Yuki Takayama

Keyword(s):

Spatial Resolution ◽

Optical Axis ◽

Focal Point ◽

Zone Plate ◽

One Dimension ◽

Depth Of Focus ◽

Third Order ◽

X Ray ◽

Limited Depth ◽

Focusing Properties

A novel type of zone plate (ZP), termed an inverse-phase composite ZP, is proposed to gain a deeper focus than the standard diffraction-limited depth of focus, with little reduction in spatial resolution. The structure is a combination of an inner ZP functioning as a conventional phase ZP and an outer ZP functioning with third-order diffraction with opposite phase to the inner ZP. Two-dimensional complex amplitude distributions neighboring the focal point were calculated using a wave-optical approach of diffraction integration with a monochromatic plane-wave illumination, where one dimension is the radial direction and the other dimension is the optical-axis direction. The depth of focus and the spatial resolution were examined as the main focusing properties. Two characteristic promising cases regarding the depth of focus were found: a pit-intensity focus with the deepest depth of focus, and a flat-intensity focus with deeper depth of focus than usual ZPs. It was found that twice the depth of focus could be expected with little reduction in the spatial resolution for 10 keV X-ray energy, tantalum zone material, 84 nm minimum fabrication zone width, and zone thickness of 2.645 µm. It was also found that the depth of focus and the spatial resolution were almost unchanged in the photon energy range from 8 to 12 keV. The inverse-phase composite ZP has high potential for use in analysis of practical thick samples in X-ray microbeam applications.

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A modified fractal zone plate with extended depth of focus in spectral domain optical coherence tomography

Journal of Optics ◽

10.1088/2040-8978/13/5/055301 ◽

2011 ◽

Vol 13 (5) ◽

pp. 055301 ◽

Cited By ~ 16

Author(s):

Q Q Zhang ◽

J G Wang ◽

M W Wang ◽

J Bu ◽

S W Zhu ◽

...

Keyword(s):

Optical Coherence Tomography ◽

Spectral Domain ◽

Zone Plate ◽

Optical Coherence ◽

Depth Of Focus ◽

Extended Depth Of Focus

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Tunable depth of focus of acoustical pupil masked Soret Zone Plate

Sensors and Actuators A Physical ◽

10.1016/j.sna.2018.11.053 ◽

2019 ◽

Vol 286 ◽

pp. 183-187 ◽

Cited By ~ 2

Author(s):

Sergio Castiñeira-Ibáñez ◽

Daniel Tarrazó-Serrano ◽

Oleg V. Minin ◽

Constanza Rubio ◽

Igor V. Minin

Keyword(s):

Zone Plate ◽

Depth Of Focus

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Depth of focus enhancement of a modified imaging quasi-fractal zone plate

Optics & Laser Technology ◽

10.1016/j.optlastec.2012.03.012 ◽

2012 ◽

Vol 44 (7) ◽

pp. 2140-2144 ◽

Cited By ~ 7

Author(s):

Qinqin Zhang ◽

Jingang Wang ◽

Mingwei Wang ◽

Jing Bu ◽

Siwei Zhu ◽

...

Keyword(s):

Zone Plate ◽

Depth Of Focus

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Design of Acoustical Bessel-Like Beam Formation by Tunable Angular Spectrum in Soret Zone Plate Lens

10.20944/preprints201809.0181.v1 ◽

2018 ◽

Author(s):

Daniel Tarrazó-Serrano ◽

Sergio Castiñeira-Ibáñez ◽

Oleg V. Minin ◽

Pilar Candelas ◽

Constanza Rubio ◽

...

Keyword(s):

Spatial Resolution ◽

Angular Spectrum ◽

Zone Plate ◽

Experimental Measurements ◽

Depth Of Focus ◽

Bessel Beams ◽

Fundamental Parameters ◽

Diffractive Lenses ◽

Beam Formation ◽

Image Performance

The image performance of acoustic and ultrasound sensors depends on several fundamental parameters such as depth of focus or spatial resolution. There are currently two different type of acoustic diffractive lenses: those which form a diffraction-limited spot with a shallow depth of focus (zone plates) and lenses which form an extended focus (quasi-Bessel beams). In this paper, we investigate a pupil-masked Soret zone plate which allows the tunability of a normalized angular spectrum. It is shown that the depth of focus and the spatial resolution can be modified, without changing the lens structure, by choosing the size of the amplitude pupil mask. This effect is based on the transformation of spherically converging waves into quasi-conical waves, due to the apodization of the central part of the zone plate. The theoretical analysis is verified with both numerical simulations and experimental measurements. A Soret zone plate immersed in water with D/2F=2.5 and F=4.5$\lambda$, changes its depth of focus from 2.84$\lambda$ to 5.9$\lambda$ and the spatial resolution increases from 0.81$\lambda$ to 0.64$\lambda$ at a frequency of 250 kHz, by modifying the pupil mask dimensions of the Soret zone plate.

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Design of Acoustical Bessel-Like Beam Formation by a Pupil Masked Soret Zone Plate Lens

Sensors ◽

10.3390/s19020378 ◽

2019 ◽

Vol 19 (2) ◽

pp. 378 ◽

Cited By ~ 2

Author(s):

Daniel Tarrazó-Serrano ◽

Sergio Castiñeira-Ibáñez ◽

Oleg Minin ◽

Pilar Candelas ◽

Constanza Rubio ◽

...

Keyword(s):

Angular Spectrum ◽

Lateral Resolution ◽

Zone Plate ◽

Depth Of Focus ◽

Bessel Beams ◽

Fundamental Parameters ◽

Diffractive Lenses ◽

Beam Formation ◽

Different Types ◽

Image Performance

The image performance of acoustic and ultrasound sensors depends on several fundamental parameters such as depth of focus or lateral resolution. There are currently two different types of acoustic diffractive lenses: those that form a diffraction-limited spot with a shallow depth of focus (zone plates) and lenses that form an extended focus (quasi-Bessel beams). In this paper, we investigate a pupil-masked Soret zone plate, which allows the tunability of a normalized angular spectrum. It is shown that the depth of focus and the lateral resolution can be modified, without changing the lens structure, by choosing the size of the pupil mask. This effect is based on the transformation of spherically-converging waves into quasi-conical waves, due to the apodization of the central part of the zone plate. The theoretical analysis is verified with both numerical simulations and experimental measurements. A Soret zone plate immersed in water with D/2F = 2.5 and F = 4.5 λ changes its depth of focus from 2.84 λ to 5.9 λ and the lateral resolution increases from 0.81 λ to 0.64 λ at a frequency of 250 kHz, by modifying the pupil mask dimensions of the Soret zone plate.

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Record Wear Studies by Scanning Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100101578 ◽

1968 ◽

Vol 26 ◽

pp. 364-365

Author(s):

M.D. Coutts ◽

E.R. Levin ◽

J.G. Woodward

Keyword(s):

Electron Microscopy ◽

Constant Velocity ◽

Peak Velocity ◽

Great Depth ◽

Depth Of Focus ◽

Sweep Frequency ◽

Transmission Electron ◽

Test Record ◽

Lateral Mode ◽

Scanning Electron

While record grooves have been studied by transmission electron microscopy with replica techniques, and by optical microscopy, the former are cumbersome and restricted and the latter limited by lack of depth of focus and resolution at higher magnification. With its great depth of focus and ease in specimen manipulation, the scanning electron microscope is admirably suited for record wear studies.A special RCA sweep frequency test record was used with both lateral and vertical modulation bands. The signal is a repetitive, constant-velocity sweep from 2 to 20 kHz having a duration and repetitive rate of approximately 0.1 sec. and a peak velocity of 5.5 cm/s.A series of different pickups and numbers of plays were used on vinyl records. One centimeter discs were then cut out, mounted and coated with 200 Å of gold to prevent charging during examination. Wear studies were made by taking micrographs of record grooves having 1, 10 and 50 plays with each stylus and comparing with typical “no-play” grooves. Fig. 1 shows unplayed grooves in a vinyl pressing with sweep-frequency modulation in the lateral mode.

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