一种彩虹全息凹印卷料的多光谱颜色测量技术

A New Measurement Method for Multi-spec Color of Rainbow Holographic Product in Roll-to-roll Printing

目的针对彩虹全息凹印卷料品的颜色测量问题,研究一套专用的光源和多光谱成像系统。方法基于衍射抑制模型,设计一种穹顶光源,采用类似积分球的照明方式,使入射光线能在(-π/2~π/2)均匀入射,遍布全息印刷品的照射表面。采用多光谱CCD相机,在一个CCD相机中形成12~36个光谱通道,相当于将传统的RGB三通道相机扩大为36个通道的相机。结果穹顶光源使得光源内部的发光强度均匀,对全息印刷品表面的衍射光线有明显抑制作用,削弱了衍射光栅的色散作用,通过多光谱相机成像获得了产品在多个通道的光谱特性。结论结合穹顶光源设计的多光谱成像系统很好地获取了多光谱颜色表达,测量精度在2个色差范围内。

The paper aims to develop a special light source and multi-spec imaging system to solve the color measurement problem of rainbow holographic in roll-to-roll printing. The special dome light source was designed based on the diffraction inhibition model to achieve uniform light incidence （-π/2-π/2） on the irradiated surface as integrating sphere. The multi-spec CCD camera, which was similar to the traditional RGB three-channel camera, can generate 12 - 36 spectral channels images. The dome light source achieved uniform light intensity, had apparent inhibiting effect on diffraction light on surface of holographic printed product, and weakened the dispersion effect of diffraction grating. And spectral characteristics in multiple channels of product were obtained by multi-spec camera imaging. The multi-spec imaging system with dome light source design has good color expression, which can achieve accuracy within two degrees of color difference.