| CPC G02B 26/101 (2013.01) [G01S 7/4817 (2013.01)] | 7 Claims | 

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               1. A method of determining and maintaining a scanning condition for optimal Lissajous scanning performed by a processing device, the method comprising: 
            selecting a frequency combination and a mapping time delay difference, when minimum scanning density according to the mapping time delay difference in the frequency combination within a preset frequency range for two axes is maximum, as an optimal scanning condition; and 
                maintaining optimal scanning by applying a modulated drive phase offset to compensate for a deviation between an actual time delay difference and an optimal time delay difference selected as the optimal scanning condition due to a delay index adjusted according to an actual phase change, 
                wherein a mapping time delay is adjusted by a delay index of each axis, a phase of each axis has a phase change amount determined by the delay index, and the modulated drive phase offset is obtained by reflecting the phase change amount. 
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