Design Of Piezoelectric Objective Lens Controller Used In Digital Confocal Microscope Technology

For the microscope micro-displacement control requirements of the serial optical sections microscopic image acquisition in the digital confocal microscope technology, a piezoelectric objective lens actuator is used to drive the microscope objective lens to achieve the nanoscale equal spaced micro displacement. According to the actual needs and the researches, a controller is designed for the drive and control of the piezoelectric objective lens actuator. The piezoelectric objective lens controller contains two parts, power supply and control algorithm, and is applied to ultimately achieve the continuous nanoscale equal spaced step control of the objective lens.In accordance with the characteristics of piezoelectric ceramics and actual control needs, the design specifications of the piezoelectric objective lens controller are put forward by calculations and experimental tests. Then the problems of the power supply developed by our research group are analyzed through experiments. And combined with the research actualities and the design specifications, a novel low-cost power supply based on LTC6090 are proposed. The voltage type power supply base on error amplifier is selected to be the primary design form of the power supply of the controller. Then using the error amplifier circuit which constituted by the low-power operational amplifier LTC6090 and transistors to replace the common high-voltage power operational amplifier, and applying a bridge circuit to improve the output voltage and current. The performance of the power supply is tested on the actual circuits, and the test results show that the power supply has the characteristics of floating unipolar 150V voltage output,0.014% output linearity,±100mA peak current, less than 15mV static ripple with load, and good square wave response. The power supply can reach the performance of mainstream products of piezoelectric ceramic power supply, and the cost is effectively reduced, so it can meet the control requirements of the piezoelectric objective lens actuator.As the power supply, the practical application problems in the control algorithm using in the existing piezoelectric objective lens controller developed by our research group is also be analyzed. Then after the researches and applications of the complex control algorithm combined with feedforward compensation and closed-loop control which widely used in recent years, a conclusion is obtained from the comparison of the experimental results:The modeling of the inverse model feedforward compensation control algorithm is found to be difficult to achieve nanometer level, so the inverse model-based algorithm and complex algorithm based on it cannot feed the requirements of the nanoscale step control. Finally, choose the PID closed-loop control algorithm as the control algorithm, and test the controller according to the design specifications. The test results show that the proposed piezoelectric objective lens controller is basically achieved the design specifications, and can provide a static control error of less than lOnm and achieve a 50nm equal spaced step control. The controller establishes a foundation for the serial optical sections acquisition applications in future.This thesis elaborates the unsolved problems of the design process, and proposes the follow-up prospects based on the analysis of the problems.