Corneal thickness measuring method based on subdivision of pulses

A technology of corneal thickness and measurement method, which can be used in eye testing equipment, eye examination, etc., can solve problems such as the limitation of the center frequency of the resolution emission wave, and achieve the effect of high resolution, easy popularization and promotion

Active Publication Date: 2012-07-25
XUZHOU KAIXIN ELECTRONICS INSTR
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Problems solved by technology

The resolution of the traditional thickness measurement method based on pulse reflection is limited by the center frequency of the transmitted wave, the sampling rate of the echo signal and the system noise

Method used

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  • Corneal thickness measuring method based on subdivision of pulses
  • Corneal thickness measuring method based on subdivision of pulses
  • Corneal thickness measuring method based on subdivision of pulses

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Embodiment Construction

[0017] Below in conjunction with embodiment, further illustrate the present invention.

[0018] Example transmit waveforms are in the form of simple harmonics ,Right now

[0019]

[0020] In the formula ω , φ are the angular frequency and the initial phase, respectively. The received reflected wave is modulated by the medium, and the reflection characteristic of the medium is defined as R(x), and the form of the echo can be recorded as:

[0021]

[0022] If the value of the echo reaches the maximum R(x) maximum while Equal to 1 or -1. R(x) The maximum means the reflected echo of the interface, by adjusting the initial phase φ It can make the ultrasonic wave reach the interface at the moment when the sound pressure is maximum. If the subdivision phase is Φ , then in addition to the integer multiples of the half-wavelength in the distance, there are also Φ / π fractional multiples of half-wavelength. The more subdivision steps N, the higher the accuracy. ...

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Abstract

The invention provides a corneal thickness measuring method based on subdivision of pulses, which belongs to an ultrasonic thickness measuring method. Measurement precision of the corneal thickness measuring method can achieve the micrometer level. Subdivision of pulse is realized by the aid of phase shift of a transmitted pulse, an ultrasonic signal which is reflected back is received, the frontwall and the rear wall of a cornea are judged, a single measurement result is calculated, a next transmitted pulse shifts by a subdivided phase of a pi phase, an ultrasonic signal which is reflected back is received, a current measurement result is obtained, and after total transmitted pulses shift by the pi phase, a last measurement result is obtained. Accurate distances from two sides of the cornea to an ultrasonic sensor are calculated according to the phases corresponding to the maximum values of all the subdivision results, and the final cornea thickness value is obtained by means of subtracting the two accurate distances. If subdivided steps are N, measurement precision is 1 / N of semi-wavelength. The corneal thickness measuring method has the advantages that the ultrasonic thicknessmeasuring method is realized by the aid of subdivision of pulses, the measurement precision can achieve the micrometer level. Resolution ratio of the method is high, center frequency of a probe does not need to be too high, and the corneal thickness measuring method is easy to be popularized.

Description

technical field [0001] The invention relates to a corneal instrument and a measurement method, in particular to a corneal thickness measurement method based on a pulse subdivision method and a corneal thickness gauge; it belongs to an ultrasonic thickness measurement method. It is a method of ultrasonic thickness measurement using pulse subdivision method. It is also a method to achieve non-invasive measurement of corneal thickness. Background technique [0002] Corneal thickness is the distance between the front and back surfaces of the cornea, and its thickness is generally measured using a corneal pachymeter. The traditional method of using a corneal pachymeter to measure corneal thickness (patent application number 201120034105.0) is based on the two peaks of echoes from both sides of the cornea The time interval between to obtain corneal thickness, the measurement accuracy is limited by the center frequency of the probe, generally the same order of magnitude as the hal...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): A61B8/10
Inventor 康恺刘涛步国正
Owner XUZHOU KAIXIN ELECTRONICS INSTR
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