自聚焦伺服的激光测微技术

The Application of CD Optical Head to Micro Displacement Measurement

以激光ＣＤ 光学头为基础，提出新颖的自聚焦伺服测微工作原理，并以此原理试制测微仪。利用半导体激光器作光源，ＣＤ 光学头作高精度位移检测传感器，并利用高分辨率、高动态响应的压电晶体作微位移驱动源，建立实时闭环反馈的自聚焦伺服系统，由单片机进行控制，实现自动跟踪测量。系统首先在±５００μｍ 范围内进行寻焦搜索，实现光学头聚焦于被测表面，随后立即进入闭环聚焦伺服状态，对微位移进行检测。可获得±０．１μｍ 以上的测量精度，测量范围±１０μｍ ，测量形式为非接触测量。同时，该测微仪还有成本低、体积小、使用方便等优点，是一种值得推广的新方法。

In this paper a novel principle of micrometer is presented, which is based on CD optical head and aimed to obtain a high accuracy of less than 0.1μm. By applying semi conductor laser tube as optical source, CD optical head as displacement sensor, and by utilizing piezoelectric crystal of high resolution and dynamic response as displacement actuator, we set up a closed loop feedback system, which is controlled as displacement actuator, we set up a closed loop feedback system, which is controlled by single chip computer and able to realize auto measuring. First, the system searches the focus in a range of ±500μm, and then makes a non contact measurement of the micro displacement with accuracy of less than 0.1μm and range of ±10μm. Meanwhile, the measurement system is characterized by simple structure, low cost and easy usage. So this new method is worthy of wide application.