Acoustic lens with variable focal length for photoacoustic microscopy

2013 ◽  
Vol 114 (19) ◽  
pp. 194703 ◽  
Author(s):  
Chaolong Song ◽  
Lei Xi ◽  
Huabei Jiang
Keyword(s):  
Focal Length ◽  
Photoacoustic Microscopy ◽  
Acoustic Lens

Constant focal length acoustic lens

1992 ◽  
Vol 92 (1) ◽  
pp. 631-631
Author(s):  
Morton Stimler
Keyword(s):  
Focal Length ◽  
Acoustic Lens

Practical Design of a High Frequency Phased-Array Acoustic Microscope Probe: A Preliminary Study

2017 ◽  
Author(s):  
Jeong Nyeon Kim ◽  
Richard L. Tutwiler ◽  
Judith A. Todd
Keyword(s):  
High Frequency ◽  
Phased Array ◽  
Incident Angle ◽  
Focal Length ◽  
Acoustic Microscopy ◽  
Mode Shapes ◽  
Single Element ◽  
Acoustic Microscope ◽  
Acoustic Lens ◽  
Microscope Probe

Scanning acoustic microscopy (SAM) has been a well-recognized tool for both visualization and quantitative evaluation of materials at the microscale since its invention in 1974. While there have been multiple advances in SAM over the past four decades, some issues still remain to be addressed. First, the measurement speed is limited by the mechanical movement of the acoustic lens. Second, a single element transducer acoustic lens only delivers a predetermined beam pattern for a fixed focal length and incident angle, thereby limiting control of the inspection beam. Here, we propose to develop a phased-array probe as an alternative to overcome these issues. Preliminary studies to design a practical high frequency phased-array acoustic microscope probe were explored. A linear phased-array, comprising 32 elements and operating at 5 MHz, was modeled using PZFlex, a finite-element method software. This phased-array system was characterized in terms of electrical input impedance response, pulse-echo and impulse response, surface displacement profiles, mode shapes, and beam profiles. The results are presented in this paper.

scholarly journals Numerical calculation and measurement for the focus field of concave spherical acoustic lens transducer

2019 ◽  
Vol 283 ◽  
pp. 05007
Author(s):  
Jun Zhang ◽  
Yi Chen ◽  
Liuqing Yang
Keyword(s):  
Wave Propagation ◽  
Incident Angle ◽  
Focal Length ◽  
Sound Field ◽  
Numerical Data ◽  
Scanning System ◽  
Acoustic Lens ◽  
Wave Propagation Method ◽  
The Relationship ◽  
Important Basis

How to accurately calculate the sound field formed by acoustic lenses is an important basis for the design of acoustic lens transducers. The radiation sound field distribution of the physical model of acoustics lens is simulated by numerical methods, including the ray propagation method and the wave propagation method. The ray propagation method can only get the focal length without considering the wave characteristics property, while the wave propagation method takes into account the amplitude and phase factors of the wave, and by which the distribution of the whole sound field can be got. The relationship between the property of refractive wave and incident angle of incident wave is analyzed, and theoretical results of the distribution of the focal field are obtained. The actual sound field of the real transducer is measured by acoustic field scanning system, and the measured results of focal length and focal area are obtained. The comparison and analysis of the numerical data and measured data show that the wave propagation method can be used to predict the focus field of concave spherical acoustic lens transducer accurately and effectively.

Resolution Attainable With the Present Day STEM

1973 ◽  
Vol 31 ◽  
pp. 230-231 ◽  
Author(s):  
J. S. Wall ◽  
J. P. Langmore ◽  
H. Isaacson ◽  
A. V. Crewe
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Incident Beam ◽  
Scanning Transmission Electron Microscope ◽  
Aperture Size ◽  
Magnetic Lens ◽  
Peak Intensity ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Half Angle

The scanning transmission electron microscope (STEM) constructed by the authors employs a field emission gun and a 1.15 mm focal length magnetic lens to produce a probe on the specimen. The aperture size is chosen to allow one wavelength of spherical aberration at the edge of the objective aperture. Under these conditions the profile of the focused spot is expected to be similar to an Airy intensity distribution with the first zero at the same point but with a peak intensity 80 per cent of that which would be obtained If the lens had no aberration. This condition is attained when the half angle that the incident beam subtends at the specimen, 𝛂 = (4𝛌/Cs)¼

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