Gray scale echography with simultaneous a mode presentation a new apparatus for high resolution ultrasonograms
A diagnostic ultrasonic system has been developed for simultaneous display of quantitative A mode and gray scale B mode presentations. An independent calibrator and preset amplification levels allow the apparatus to be calibrated for precise, repeatable examinations. A wide range of echo amplitude information is available to the clinician by the use of selective logarithmic signal compression. Distance measurements in the eye and the orbit are made to 0.1 mm precision and are displayed numerically on the control panel. The newer signal processing techniques provide high‐resolution imaging of ophthalmic structures over a wide system bandwidth. Sensitivity has been improved to image structures heretofore not observable with ultrasonic instruments. This technique is the basis for recently initiated clinical studies.
A New Technique for Improving the Sharpness of Television Pictures
In conjunction with the CBS color-television system a method has been developed for improving the apparent picture definition, called "crispening." It uses nonlinear circuitry to decrease the apparent rise time of an isolated step input which is applied to a bandwidth limited system. This gives the color-television pictures (with the exception of repetitive patterns representing frequencies beyond system cutoff) the appearance of having been transmitted through a system of greater bandwidth. The basic idea is to add to a waveform with a slow transition a second waveform, representing the difference between the desired waveform and the original waveform. A simple circuit is described which utilizes nonlinear means for reforming the roughly triangular differential of the step signal into a narrower "spike," roughly triangular in shape, which is superimposed on the original waveform to obtain a response corresponding to about half the original rise time. Various crispening circuits have been designed for specific applications and will be discussed in more detail. These crispening circuits can be applied to standard monochrome pictures. The resultant increase in sharpness, however, would be less apparent because of the law of diminishing returns. The doubling of the bandwidth, that is, halving of the rise time (which is the effect of crispening) will be less apparent in the already high-resolution monochrome pictures than in the lower resolution color pictures. Various subject matter and test patterns as photographed from the screen of color receivers are shown for 4.
The application of ultrasonic locating techniques to ophthalmology. II. Ultrasonic slit lamp in the ultrasonic visualization of soft tissues.
Introduction This is a preliminary report of the visualization of the interior of the lightopaque eye and the retro-ocular areas by pulsed ultrasonic echographic methods. Non-radio-opaque foreign materials, such as wood and plastics, may also be visualized, as well as soft tissue pathology. At present no other method can yield the information obtained by the technique to be described. A comparison of the visual appearance of a normal beef eye, the x-ray appearance, and the sonic appearance graphically illustrates this contention (Fig. 1). The x-ray demonstrates only the gross outline of the eye. The ultrasonogram reveals a cross section of the internal structure of the eye equivalent in detail to a low-power photomicrograph. Serial ultrasonic tomograms (Figs. 13 to 21) yield a composite picture of the eye at all levels without in any way altering the tissues. Precise direct measurement of the depth within the tissue is possible with this