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KR-102962031-B1 - Frequency modulation-based Lissajous scanning apparatus and method for improving image pixel resolution

KR102962031B1KR 102962031 B1KR102962031 B1KR 102962031B1KR-102962031-B1

Abstract

One embodiment of the present invention provides a frequency modulation-based Lissajous scanning device for improving image pixel resolution, comprising: a frequency generator that generates first signals of different frequencies that form the basis for generating a scan signal to control a scanner of an optical imaging device; a frequency modulator that generates second signals modulated to have different time domains or phases of the first signals; a scan signal integrator that generates a scan signal by integrating the second signals to perform Lissajous scanning; and a resolution verification unit that verifies the resolution of an image obtained as a result of the scanner performing a scan according to the scan signal.

Inventors

  • 전만식
  • 김지현
  • 성대운

Assignees

  • 경북대학교 산학협력단

Dates

Publication Date
20260508
Application Date
20240423
Priority Date
20231207

Claims (8)

  1. A frequency generator that generates first signals of different frequencies that form the basis for generating a scan signal to control a scanner of an optical imaging device; A frequency modulation unit that generates second signals modulated to have different time domains or phases from the first signals; A scan signal integrator that generates a scan signal by integrating the second signals to perform Lissajous scanning; and It includes a resolution verification unit that verifies the resolution of an image obtained as a result of the scanner performing a scan according to the above scan signal, The Lissajous scan regions corresponding to the first signals of the above different frequencies are different from each other, and The scan signal integrator connects the second x-axis signals among the second signals to form a final x-axis signal and connects the second y-axis signals among the second signals to form a final y-axis signal, thereby generating the scan signal combined such that the final x-axis signal and the final y-axis signal are orthogonal. The scan signal integrator integrates the second signals to simultaneously scan by dividing the imaging area, and generates the x-axis final signal and the y-axis final signal by connecting the second signals by adding a triangular wave signal or a sine wave signal at discontinuous points between the second signals and matching the starting values. The frequency generator divides the imaging area into three pixel regions and generates the first signals, which are cosine signals of three different frequencies, corresponding to each pixel region. The frequency modulation unit modulates the first signals to uniformly cover the imaging area to generate the second x-axis signals and the second y-axis signals, and A frequency modulation-based Lissajous scanning device for improving image pixel resolution, wherein the scan signal integrator combines the second x-axis signals and the second y-axis signals to combine relative frequency and phase differences, thereby generating the scan signal that forms a continuous scanning pattern moving along a path in a two-dimensional plane.
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  5. As a frequency modulation-based Lissajous scanning method for improving image pixel resolution controlling a scanner of an optical imaging device, A step in which a frequency generator generates first signals of different frequencies that form the basis for generating a scan signal; A frequency modulation unit generates second signals by modulating the first signals to have different time domains or phases; A step of generating a scan signal by integrating the second signals so that the scan signal integration unit performs Lissajous scanning; and The resolution verification unit includes a step of verifying the resolution of an image obtained as a result of the scanner performing a scan according to the scan signal, wherein The step of generating the second signals above is, The above frequency generator divides the imaging area into pixel regions corresponding to each of the first signals; and The frequency modulation unit scans each pixel area in different time domains and phases, and includes the step of modulating the time domains and phases of the first signals so that the laser beam is uniformly distributed over the entire imaging area during scanning. The step of generating the above scan signal is, The step of integrating the second signals so that the scan signal integrator simultaneously scans the pixel regions, and adding a triangular wave signal or a sine wave signal at discontinuous points between the second signals; and It includes a step of ensuring that the signal forms a continuous flow at the discontinuous point by matching the starting values of each second signal to match each other, In the step of generating the first signals, the frequency generator divides the imaging area into three pixel regions and generates the first signals, which are cosine signals of three different frequencies corresponding to each pixel region. In the step of generating the second signals, the frequency modulation unit modulates the first signals to uniformly cover the imaging area to generate three second x-axis signals and three second y-axis signals, and Frequency modulation-based Lissajous scanning method for improving image pixel resolution, wherein in the step of generating the scan signal, the scan signal integrator combines the three x-axis second signals and the three y-axis second signals to combine relative frequency and phase differences, thereby generating the scan signal that forms a continuous scanning pattern moving along a path in a two-dimensional plane.
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Description

Frequency modulation-based Lissajous scanning apparatus and method for improving image pixel resolution The present invention relates to a frequency modulation-based Lissajous scanning device and method for improving image pixel resolution, and more specifically, to a frequency modulation-based Lissajous scanning device and method for improving image pixel resolution in Lissajous scanning, which is an operating method of a scanner used for fast scanning in optical imaging. Generally, Lissajous scanning is a scanning method that utilizes complex patterns generated when two vibrations occur simultaneously along two mutually perpendicular axes. Primarily used in laser scanning systems or optical imaging, Lissajous scanning is implemented through a combination of two galvanometer scanners along the x and y axes. Each galvanometer is driven at a different frequency, and their interaction creates the Lissajous pattern. The key feature of Lissajous scanning is its ability to generate various patterns based on the ratio and phase difference between the two frequencies. By utilizing these patterns, light can be focused along various paths within the scan area, or specific points can be imaged at high resolution. Lissajous scanning is particularly useful for high-speed imaging of biological samples or in Optical Coherence Tomography (OCT), which requires high resolution. In these fields, Lissajous scanning plays a crucial role in precisely scanning targets using laser beams or other light sources and generating high-resolution images or data. Conventional Lissajous scanning is widely used because it has the advantage of being able to scan x and y axes simultaneously. However, it has the disadvantage that the pixel resolution in the center is significantly lower than that in the outer areas, making it impossible to achieve the same optical resolution. Figure 1 shows the scanning location when using a conventional single-frequency-based Lissajous scanning method. In the conventional single-frequency-based Lissajous scanning location shown in Figure 1, black represents empty space that cannot be measured, and white represents the location where the scanner proceeds with the scan. As such, it can be clearly seen that the pixel resolution of the central area is significantly lower than that of the outer area in the conventional Lissajous scanning method because a single frequency is used. While it was possible to use the basic Lissajous scanning method using a single frequency for existing low-resolution systems, for systems requiring high resolution, signal loss may occur depending on the location because the resolution cannot be measured uniformly with the conventional method, and there are limitations in mapping structural information or uniformly measuring pixel-by-pixel information. Figure 1 shows the scanning location when using the conventional single-frequency based Lissajous scanning method. FIG. 2 shows an OCT device equipped with a frequency modulation-based Lissajous scanning device for improving image pixel resolution according to an embodiment of the present invention. FIG. 3 is a diagram illustrating a frequency modulation-based Lissajous scanning device for improving image pixel resolution according to an embodiment of the present invention illustrated in FIG. 2. Figure 4 shows different scanning positions for each case when the frequency is modulated. FIG. 5 shows the result of scanning by a frequency modulation-based Lissajous scanning device for improving image pixel resolution according to one embodiment of the present invention. Figure 6 shows a frequency modulation-based Lissajous scanning device for improving image pixel resolution that connects three different x-axis frequencies. Figure 7 shows a frequency modulation-based Lissajous scanning device for improving image pixel resolution that connects three different y-axis frequencies. Figure 8 shows the phenomenon where discontinuous points appear when three different x-axis frequencies are combined to form the main signal, as the position of the scanner is different. Figure 9 shows the phenomenon where discontinuous points appear when three different y-axis frequencies are combined to form the main signal, as the position of the scanner is different. Figure 10 shows the final main signal corrected by connecting the discontinuous points in Figures 8 and 9. FIG. 11 illustrates a frequency modulation-based Lissajous scanning method for improving image pixel resolution according to an embodiment of the present invention. The present invention is susceptible to various modifications and may take various forms; therefore, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the invention to the specific disclosed forms, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention.