Measuring and testing – Vibration – By mechanical waves
Patent
1985-09-27
1989-04-04
Levy, Stewart J.
Measuring and testing
Vibration
By mechanical waves
12866106, G01N 2904
Patent
active
048174327
ABSTRACT:
Disclosed is a digital ultrasonic instrument for measuring the corneal thickness (often referred to as a pachymeter) and for measuring the axial length of the eye (often referred to as a biometric ruler). A number representing corneal thickness or axial length is displayed digitally on a liquid crystal display. The pachymeter incorporates a 20 MHz solid phase piezoelectric transducer, a microprocessor, a gate array, a hybrid analog receiver circuit, a liquid crystal display and four batteries. When axial length is measured, the instrument operates as a biometric ruler, a 10 MHz transducer is used and the software in the microprocessor is modified. Ultrasonic echoes generated by the transducer and various interfaces in the eye are sampled at the rate of 40 MHz which results in equal or greater sensitivity, resolution and accuracy as compared to other pachymeters and biometric rulers currently available. The 40 MHz sample rate is accomplished by use of a grey code counter and a binary counter, each of which is sampled twice after an ultrasonic echo is detected. The two grey code samples are compared to determine a valid sample period. A counter value obtained during a valid sample period is recorded in a shift register and compared to subsequent counter values corresponding to subsequent ultrasonic echoes. The apparatus for correlating ultrasonic echoes with particular counter values assures that the counter will be sampled at a point in time when the counter is stable as opposed to being in a state of transition. The apparatus allows for a counter accuracy of 25 ns.
REFERENCES:
patent: 4398420 (1983-08-01), Haesen et al.
patent: 4412248 (1983-10-01), Carmen
patent: 4564018 (1986-01-01), Hutchison et al.
Dally William J.
Feldon Steven E.
Karns Scott A.
Mezack Gary
Wallace David A.
Arana Louis M.
Design Team Partners
Levy Stewart J.
LandOfFree
Digital ultrasonic instrument for ophthalmic use does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Digital ultrasonic instrument for ophthalmic use, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Digital ultrasonic instrument for ophthalmic use will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-170659