为解决传统光学检测方法存在的对已刻（干刻）区域无法检测、潜在曝光可能性、系统光路复杂以及灵敏度较低等缺点，提出了一种可用于激光直写光刻自动聚焦的高灵敏度流量计式位移检测系统。详细介绍了系统的原理、系统设计、实验方法以及误差分析等。根据流量传感器检测得到的气流变化，可以判断光刻系统中聚焦系统是否离焦以及离焦量的大小。再将此气流变化量转化为电压值反馈至压电陶瓷(PZT)执行机构，通过执行机构实现自动聚焦。由于喷嘴挡板系统可以建立喷嘴挡板间距与喷嘴内部压力的关系，而流量敏感度要高于压力敏感度，故采用了热线探针来检测系统流量变化。实验证明，该方法能够准确检测系统离焦量，系统测量精度可达100 nm，频率响应可达20 Hz，量程可达20 μm。而且在一定范围内喷嘴挡板间距与空气流量变化具有非常好的线性关系。

In order to overcome the shortcoming of the conventional optical focusing method, such as unable to detect on the patterned area, photoetching material′s potential exposure, complicated laser path and low sensitivity, method of using high sensitivity pneumatic micro-distance measurement system for lithography autofocus is investigated. The principle, design, method and error analysis are introduced. The pneumatic micro-distance sensor can detect the varity of air flow to determine the defocusing amount. The varity of air flow is transfered into voltage for piezoelectric translator, and the piezoelectric ceramics will be drived to move to the focus range. Because the air pressure in nozzle flapper is related with detection distance, and the air flow is more sensitive than pressure, hotwire probe is used to detect the varity of air flow. The result shows that the accuracy of the measurement system can reach 100 nm, frequency response can come to 20 Hz, the measuring range can be 20 μm. Within a certain range, the detection distance has quite good linear relation with the varity of air flow.