基于渐变滤光薄膜的图像传感器片上高光谱分光方法研究

Dispersion function is integrated into image sensor directly by the on-chip integration hyperspectral method, which is the key to further miniaturization of spectral equipments. There are many problems such as poor light splitting properties and narrow working bandwidth in the existing on-chip integration methods. A new idea of integrating variable filters onto image sensors is put forward to realize on-chip hyperspectral detection with high spectral resolution and wide operation range. The variable filter is a kind of highly integrated dispersion element, which has a continuous change of the central wavelength. This project intends to carry out a series of researches including the theory and characteristics of variable filters with ultra narrow band, wide cutoff and high dispersion coefficient, test methods of variable filter, and the coupling characteristics of thin film and sensor. A number of key technologies will be breaked through, such as the preparation and characterization of high precision variable filter and the lossless integration of thin film devices with photosensitive devices. At last, an on-chip hyperspectral detector with high spectral resolution and wide operating range will be obtained, and a new way of multi function integration for image sensor will be provided.

图像传感器片上集成高光谱探测方法将分光功能直接集成到探测器上，是光谱分析或成像设备进一步小型化的关键。现有高光谱片上集成方法存在分光特性差、工作带宽窄等问题。本申请提出将渐变滤光薄膜集成到图像传感器上，以实现高光谱分辨率、宽工作范围片上高光谱探测。渐变滤光薄膜是一种高集成分光元件，不同位置具有连续变化的通带中心波长，与探测器件耦合可实现分光探测功能一体化。本项目拟开展超窄带、宽截止、高色散系数渐变滤光薄膜理论及特性研究、波长渐变型滤光薄膜离散化测试方法研究、薄膜与探测器兼容耦合特性研究。突破高精度渐变滤光片制备与表征、薄膜器件与感光器件无损集成等关键技术，获得具备高光谱分辨率，宽工作范围的片上高光谱探测器，为图像传感器多功能集成提供一种新的方法。

线性渐变滤光片是一种新型的色散器件，采用光学薄膜的手段实现了高度集成化的色散功能，可以极大的优化光谱分光系统的结构。进一步探索通过渐变滤光片与图像传感器的集成，实现色散器件与成像器件的功能集成，可获得芯片级高光谱分光能力。.首先建立准确的渐变薄膜物理模型,设计沉积速率衰减控制机制，制备出厚度渐变薄膜。基于特征矩阵算法，依据法布里-珀罗多腔窄带滤光片的设计原理进行窄带滤光片膜系的设计，依据双侧截止的设计原则，通过多个Bragg反射板并联的方式设计宽带截止膜系。其次设计渐变薄膜测量标定方案，基于分光光度计建立单层渐变薄膜测试系统，准确测定薄膜不同位置的厚度及薄膜的厚度变化率。优化小光斑测试系统，对窄带滤光片的技术指标进行精确的采样标定。进一步深入研究薄膜厚度控制方法，综合使用光控、晶控及时间控制等膜厚控制方式。基于波长干涉理论优化膜厚光控算法，对规整膜系进行精确的控制和有效的误差补偿；精确标定晶控校正因子和薄膜沉积速率，对非规整膜系进行精确控制。最终在石英基底上实现了渐变滤光片的制备，通过设计的优化及工艺的创新研制出高品质渐变滤光薄膜，滤光片工作范围覆盖400nm-1000nm，线性变化率达到50nm/mm，光谱分辨率1.5%@CWL，带外截止度优于OD3。将线性渐变滤光片与图像传感器耦合集成起来获得了高光谱探测模块，基于此器件进行了高光谱图像数据的采集和分析，实验验证了高光谱图像传感器的色散探测一体化功能，最终实现了基于渐变滤光薄膜的图像传感器片上高光谱分光方法。