Ultrasound Camera Research Articles

High-resolution ultrasound camera with sparse array for machine diagnosis

Fault detection plays a crucial role in maintenance of mechanical systems. Ultrasound is known to be a prevalent feature of incipient fault. Industrial ultrasound detectors are widely used to find out initial malfunction of machinery. Especially, ultrasound camera can shows the fault by overlapping beamforming power distribution with optical camera image. One can easily observe where the faults are. Ultrasound transducer usually has larger size than the wavelength of its resonance frequency for highly sensitive measurement. It must be a useful approach to design sparse array that gets over the spatial aliasing problem. The aliased beamforming distribution contains high grating-lobe level due to rough spatial sampling beyond half wavenumber spacing. The sparse array is optimized to minimize maximum side-lobe level by genetic algorithm under given constraints. Being with the constraints of size and number of elements, a limitation on spatial resolution is inevitable. Functional beamforming is simple but effective to dramatically increase spatial resolution as well as reduce side-lobes. A high resolution imaging scheme based on functional beamforming with an optimal sparse array is introduced.

Ultrasound camera makes internal composite damage easy to find

An ultrasound imaging camera, which is faster and easier to use than conventional ultrasonic testing techniques, has been developed by Imperium Inc. Bob Lasser describes how it works and its potential applications.

Apparatus for real-time acoustic imaging of Rayleigh-Bénard convection

We have designed and built an apparatus for real-time acoustic imaging of convective flow patterns in optically opaque fluids. This apparatus takes advantage of recent advances in two-dimensional ultrasound transducer array technology; it employs a modified version of a commercially available ultrasound camera, similar to those employed in nondestructive testing of solids. Images of convection patterns are generated by observing the lateral variation of the temperature dependent speed of sound via refraction of acoustic plane waves passing vertically through the fluid layer. The apparatus has been validated by observing convection rolls in both silicone oil and ferrofluid.

Fingerprint Structure Imaging Based on an Ultrasound Camera

This paper describes the design of an ultrasound camera which has a resolution of 0.1mm. The camera allows the observation of the near surface structures of solid objects and is suitable for the finger ridge pattern imaging (i.e., pattern which is reflected in a fingerprint). The device can be used for a biometric identification of individuals (for access verification). It can also be employed for all other sorts of structures which have ultrasound detectable changes in the near surface structure, both natural and artificial (e.g., created for information recording). The paper describes the current version of the camera and the physical phenomena behind its operation. Presented are also perspectives of further development of the device.

Correlation of ultrasound imaging of oral swallow with ventilatory alterations in cerebral palsied and normal children: preliminary observations.

Preliminary results of an investigation that synchronizes the videotaped output of ultrasound camera and the analog data from physiological measurements of swallowing and ventilation in normal and cerebral palsied (CP) children are presented. Four cerebral palsied children and three control children undertook a single sip-swallow of 5 ml of liquid and a solid mastication-swallow sequence on three occasions according to a defined protocol. The CP children exhibited much more variability and less control of the liquid bolus than did the controls. The ultrasound image clearly demonstrates the lack of control of the posterior of the tongue in many CP children. Some parts of the sequence of oral swallow and the time to achieve maximum anterior displacement of the hyoid bone appear to be slowed. The sequential events of swallowing show less variability as the sip-swallow proceeds from the oral voluntary to pharyngeal and lower involuntary phases. This study also identified a short-latency apnea that appears to accompany a saliva (protective) swallow and a long-latency apnea that accompanies semi-solid or liquid bolus (alimentary) swallows. Further investigations of normal and CP children utilizing a combined diagnostic imaging-physiological measurement approach will follow this initial study.

Real-time imaging with a new ultrasonic camera: part II, preliminary studies in normal adults.

A new transmission ultrasound camera system has provided focused images in real time through the abdomen of adult volunteers at average incident sound intensity levels of less than 1 mW/cm-2. The camera uses a unique acousto-mechanical lens/deflection system and a linear array of piezoelectric transducers to detect the ultrasound image. BONY STRUCTURES AND COSTAL CARTILAGES WERE CLEARLY SEEN. The colon was regularly seen and the kidney could be outlined in several subjects. The stomach and duodenal bulb were demonstrated and peristalsis was observed using a barium contrast material. The camera has the potential of extending the use of ultrasound in clinical medicine by providing an ultrasound soft tissue imaging system analogous to an x-ray fluoroscope. The need for further clinical evaluation and research to improve the images is emphasized.

Temporal Reference Acoustical Holography

This paper describes a new form of holography which obviates the need for a reference wave (real or electronically simulated). An experiment is described where reconstructions were obtained from a temporal reference acoustical hologram which was recorded at 4.8 MHz using a Sokolov ultrasound camera system. An optical method for recording a large aperture temporal reference acoustical hologram which is currently under development at the Douglas Advanced Research Laboratories, uses a double pulsed ruby laser system which introduces a quarter wavelength shift in the optical reference (or object) beam between the two pulses which are timed half an acoustic cycle apart. The quarter wavelength shift allows a subfringe interferometric hologram of an acoustically vibrating surface to be recorded, where, under appropriate conditions the intensity of the reconstructed surface is linearly proportional to the displacement of the surface between the two pulses. The pulsed laser interferometric hologram is thus an optical hologram of an acoustical temporal reference hologram. A second method of optically recording temporal reference acoustical holograms which employs a scanning cw laser is described. The important advantages expected of both these optical techniques are: (1) the total recording time is short (half an acoustic cycle) and thus the techniques are more tolerant of object motion; (2) the area of the temporal reference acoustical hologram will be significantly larger than obtainable with conventionl methods; (3) the necessity and complexity of electrons detection (large arrays or scanning) is eliminated and replaced by the high bandwidth recording capability of optical holography; (4) direct remote sensing of the acoustical object wave is achieved.

Use of color display techniques to enhance sensitivity of the ultrasound camera: Jacobs, J.E., Reimann, K., Buss, L. Materials Evaluation, Vol xxvi, No 8 (August 1968) p 155 (992)

Use of color display techniques to enhance sensitivity of the ultrasound camera: Jacobs, J.E., Reimann, K., Buss, L. Materials Evaluation, Vol xxvi, No 8 (August 1968) p 155 (992)

Ultrasound holography

Ultrasound to optical image converters can visualize objects by ultrasonic waves in optically opaque media. Ultrasound holography displaces the difficult production of conventional images by ultrasound lenses. Five examples of ultrasound object-image relations are derived from the principles of holography. The absence of a suitable ultrasound image converter restricts practical applications. Possible ultrasound detectors are outlined; for example, a potentially useful ultrasound camera with a wide aperture modification. Also, current literature of ultrasound holography is reviewed.

Ultrasound camera system for viewing acoustical holograms

A system for the simultaneous production and reconstruction of acoustical holograms is proposed. It uses electron beam scanning techniques to produce a variable transmittance hologram that can be reconstructed by the usual laser techniques.

Fourier transforms and acoustic diffraction

The authors have used Fourier analysis to derive the theoretical diffraction pattern of a plane acoustic wave passing through an object with periodic structure. By means of an ultrasound camera containing focussing lenses, they have viewed the patterns produced by actual periodic structures such as gratings and have compared the dimensions with the theory. The agreement is good enough to suggest that the method might be developed for estimating grain size in metals

The ultrasound camera—recent considerations

The future of the ultrasound camera depends on improving its resolution: present camera tubes offer only a coarse picture (45 lines). This is nevertheless fine enough to display the 2000 bits of information which is the most the ultrasonic converter end-plate in present tubes can supply. Mechanical strength is the limiting factor. The plate is cut to be half a wavelength thick so as to resonate in sympathy with the incident ultrasound. Under these circumstances the point resolution on the plate face is about half a wavelength: greater resolution calls for higher frequencies and thinner plates but plates soon become too thin to be self-supporting. Other developments are linked to optical scanning, to the use of phase-sensitive detection for examining thickness changes and the flow in fluids and to pulsed ultrasound for displaying thick objects at chosen depths. This paper is based on the author's contribution to the symposium “Acoustic imaging and pulsed light” organized by the Mine Advisory Committee of the National Academy of Sciences at Berkeley, California, in December 1964

Low power ultrasonic techniques for materials inspection

If flaw detection has really reached a plateau in its development, the author suggests why. Recording and signal processing techniques are well developed for radar and sonar but are only slowly being applied to ultrasonic examination. Laboratory techniques are too often transferred straight to the shop floor. Set against the background of materials evaluation, the pulse-echo technique falls into place beside newer methods such as resonance measurement of thickness and the ultrasonic interference micrometer; the ultrasound camera and the ultrasonic goniometer; attenuation and velocity measurements. This article is based on the author's lecture to the conference “Ultrasonics for Industry” held in London in September 1964.

The ultra-sound image camera

The ultra-sound image camera enables a visible image to be reproduced of the ultra-sound intensity distribution on the camera face. Coupled with acoustic lenses, and immersed in a suitable medium, the internal structure of substances or objects transparent to ultrasonic waves can be studied with the instrument. In its uses it is complementary to X-ray and to ultrasonic pulse-echo inspection methods. It has applications to the non-destructive testing of materials and engineering components, and also to medical diagnosis.An ultra-sound camera tube and complete viewing equipment have been built. The sensitivity for unity signal/noise ratio is 10−7 W/cm2 at the camera face, and the resolution is 0.5 mm at 4 Mc/s. It is one of several possible types of ultra-sound camera. The design is discussed, and directions into which further research and development might be taken are also considered.

The ultra-sound image camera

The ultra-sound image camera enables a visible image to be reproduced of the ultra-sound intensity distribution on the camera face. Coupled with acoustic lenses, and immersed in a suitable medium, the internal structure of substances or objects transparent to ultrasonic waves can be studied with the instrument. In its uses it is complementary to X-ray and to ultrasonic pulse-echo inspection methods. It has applications to the non-destructive testing of materials and engineering components, and also to medical diagnosis.An ultra-sound camera tube and complete viewing equipment have been built. The sensitivity for unity signal/noise ratio is 10−7 W/cm2 at the camera face, and the resolution is 0.5 mm at 4 Mc/s. It is one of several possible types of ultra-sound camera. The design is discussed, and directions into which further research and development might be taken are also considered.