A circuit for measuring circuit time delay of an integrated circuit herein provides the ability to accurately measure access time of a memory device without requiring a high performance expensive tester. The motor-controlling circuit ensures smooth control of a motor, which adjusts an optical axis, and ensures accurate repetition of a motor-stop position by way of PID and PWM control. The interference-suppressed signals may be generated by adjusting a gain and phase of the plurality of received signals to generate a corresponding plurality of adjusted signals, and combining the corresponding plurality of adjusted signals, respectively, with the plurality of received. The lens structure includes a first electrode for decelerating ions and a second electrode for accelerating the ions.