A method for measuring defocused droplet size based on quantitative calibration of defocus distance

By using the method of quantitative calibration of the off-focus distance, combining a high-speed camera and a telephoto microscope lens, a calibration function relationship was established, which solved the problem of inaccurate measurement caused by droplets leaving the focal plane under high-speed microscopic imaging, and achieved accurate measurement of droplet particle size and error reduction.

CN116046616BActive Publication Date: 2025-10-03XI AN JIAOTONG UNIV
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Patent Information

Application Number
CN202211729642.6
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2022-12-30
Publication Date
2025-10-03
Estimated Expiration
2042-12-30

AI Technical Summary

Technical Problem

The existing droplet size measurement method has a narrow focal plane under high-speed microscopic imaging, which causes some moving droplets to easily escape the focal plane, resulting in inaccurate measurements and affecting the reliability and accuracy of experimental research.

Method used

Through a method based on quantitative calibration of defocus distance, a high-speed camera and a telephoto microscope lens are used in combination with an electric translation stage and a capillary to experimentally shoot the defocusing conditions of droplets of different sizes. The calibration function relationship between the defocus distance, droplet size, magnification, grayscale diameter and grayscale gradient is established to achieve accurate measurement of the defocused droplet size.

Benefits of technology

The accuracy and reliability of droplet size measurement are improved and errors are reduced. Especially when the defocusing distance is less than or equal to twice the droplet size, the error of the corrected data is small, which is suitable for experimental data correction under various working conditions.

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Abstract

The present invention discloses a method for measuring the size of defocused droplets based on quantitative calibration of defocus distance. The method obtains the law between the defocused droplet size and the real droplet size through experiments. A high-speed camera is used in conjunction with a telephoto microscope lens to capture clear droplet images and droplet-free background images of hanging drops of different diameters D at different telephoto microscope working distances L. The electric displacement stage is adjusted to only change the front and rear positions of the droplets to obtain droplet photos at different defocus distances ε. The obtained droplet images are converted into grayscale images using a program to obtain the grayscale diameter D of the droplets. g And the average gray gradient K on both sides of the droplet; by fitting, L, D, ε and D g , K; in the specific calibration, L and droplet grayscale image are known from the shooting situation, and D is obtained through the program g and K; finally, ε and the actual droplet diameter D are obtained according to the functional relationship. The present invention realizes the accurate measurement of the actual data of the defocused droplet size measurement under conditions of different sizes and magnifications.
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