用于面曝光快速成形系统的光照度测量系统研究

Research on Illumination Measuring System for Mask Projection Stereolithography

面曝光快速成形工艺中,视图平面上的光照度大小严重影响着零件的制作精度,为控制面曝光快速成形工艺中的制作精度,需要准确测量视图平面上的光照度,为此开发了基于硅光电池的光照度测量系统.系统采用硅光电池接收光信号并转换成微弱的电流信号,经I/V转换和放大后以电压信号传送至MCU进行A/D转换,再根据数字信号和硅光电池的线性灵敏度计算出实际光照度值.为能动态调整放大电路的增益,系统采用了数字电位器作为反馈元件.利用该系统测量了面曝光快速成形工艺中视图平面上的光照度,对测量数据用MATLAB进行3次曲线拟合,建立了光照度与灰度的模型关系,利用该关系,可方便地通过改变灰度来调整视图平面上的光照度.

In the process of Mask Projection Stereolithography（MPS）,the value of illumination on the view surface of MPS has serious influence on building accuracy.In order to improve the building accuracy of MPS,it is necessary to measure the illumination accurately.An illumination measuring system with Silicon Photocell is designed and developed.The system uses photocell to convert light signal into weak current signal,which is then sent to micro control unit in the form of voltage signal to carry out A/D conversion after I/V switching and amplification,and then the system calculates the actual illumination value according to the digital value and the linear sensitivity of Silicon Photocell.For adjusting gain of the amplification circuit automatically,the system adopts digital potentiometer as feedback element.The illumination value on the view surface of MPS is measured by the system,measured data is fit with MATLAB,and the relationship between illumination and gray is established in order to adjust illumination distributing on the view surface of MPS by changing gray.