Automatic focusing method and microscope applying the method

Abstract

The invention relates to an automatic focusing method, by collecting the video signal of an original image after the imaging of an object to be measured by an objective lens in real time and changing the distance between the objective lens and the object to be measured, the automatic focusing of the object to be measured is realized. The automatic focusing method is characterized by comprising the following steps: 1. the comparable energy range value of the video signal is set and the maximum offset value M is evaluated; 2. the distance between the objective lens and the object to be measured is changed; 3. the energy of the video signal of the original image collected in real time is adjusted to be within the range of the comparable energy range of the video signal; 4. the low-frequency part of the video signal is filtered, and the high-frequency part of the video signal is retained; 5. other composite synchronous signals in the video signal are stripped; 6. small wave crests formed by interfering signals are eliminated; and 7. after being accumulated, the values of all the effective wave crests of each frame of image are compared. The method has the advantages of getting rid of the limitation of focusing process to the using occasions such as natural light, sunlight, incandescent light and the like, having high focusing accuracy and fast focusing speed.

Description

technical field [0001] The invention relates to an automatic focusing method and a microscope applying the method. Background technique [0002] Microscope autofocus technology is widely used in biology and medical research, it can improve the speed of experiments and analysis, and reduce the impact of human operation on the quality of microscopic imaging. The automatic focusing system of a common microscope usually uses a computer as the control core, uses a stepping motor as a motion control component, and uses a CCD or CMOS camera combined with a software algorithm to perform focus analysis and motion control. Publication No. CN1246929 (Application No. 98802309.1) of the Chinese patent "Analog Circuit for Autofocus Microscope System" is a typical example. This patent uses an analog circuit to measure the energy distribution of the CCD video signal to determine the degree of focus. Compared with other focusing methods, it effectively improves the real-time performance of ...

AI Technical Summary

Problems solved by technology

However, its automatic focus control module also has shortcomings: (1) The focusing process has restrictions on the use occasions, and it cannot adjust the size of the input signal adaptively, so that each frame signal involved in focusing is within the same comparable range, thereby getting rid of the focus process. The impact of occasions (natural light, daylight, incandescent light, etc.); (2) the square cumulative value used by the spectral energy is huge, and in the actual implementation of the circuit, it is easy to saturate and overflow, resulting in wrong data and resulting in misjudgment of the focus position; the circuit Although the solution uses the normalization method combined with the average lighting signal to compensate for the influence of lighting instability on the focusing results, the effect is not ideal, and the influence of lighting signals still exists

(3) Using spectral energy as the criterion, the aggregation position can be completely distinguished in theory, but in practical applications, especially in high-magnification observation focusing, due to the influence of noise, there will be multiple peaks, and an ideal focus evaluation curve cannot be obtained

All the signals are squared and accumulated, the amount of data is too large, and overflow is prone to occur. In addition, this method is greatly affected by the lighting environment, and the noise is significantly affected, which is easy to cause misjudgment, and the accuracy and stability of the focus cannot be guaranteed.

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