利用785 nm波长激光作为激发源，测量了超二代微光像增强器Na2KSb(Cs)多碱光电阴极的荧光谱.试验中发现该荧光谱不是一条光滑的高斯型曲线，而是一条在高斯型荧光谱上叠加了一定频率间隔小锯齿峰的曲线.经实验验证和理论分析证明该荧光谱上的小锯齿峰是一种干涉条纹，与超二代微光像增强器的结构有关.干涉条纹之间的间距与相邻两干涉峰波长的乘积成正比，与超二代微光像增强器的近贴聚焦距离成反比.干涉条纹调制度大小与Na2KSb(Cs)多碱光电阴极的厚度成反比.通过测量超二代微光像增强器Na2KSb(Cs)多碱光电阴极荧光谱上两相邻干涉条纹的间距和调制度，就可以测量或比较出不同超二代微光像增强器Na2KSb(Cs)多碱光电阴极的膜厚、近贴聚焦距离.研究结果对提高超二代微光像增强器阴极灵敏度和分辨力提供了一个有效的分析手段.

Fluorescence spectrum of Na2KSb(Cs) multi-alkali photocathode of the GenⅡ+ image intensifier was measured with laser of 785 nm wavelength as the excitation source. It was found that the fluorescence spectrum is not a smooth Gaussian curve, but a Gaussian fluorescence curve superposition of small jagged peaks with a certain frequency interval. Experimental and theoretical analysis show that the small fluorescent jagged peaks on the curve are actually a fringe with relationship of the structure of the GenⅡ+ image intensifier. Pitch between two adjacent interference fringes is proportion to the product of peak wavelength of two adjacent interference fringes, and inversely proportion to the proximity focusing distance of the GenⅡ+ image intensifier. Modulation of interference fringes of fluorescence spectrum is inversely proportion to the thickness of multi-alkali photocathode. By measuring the pitch of two adjacent interference fringes and modulation of Na2KSb(Cs) multi-alkali photocathode of the GenⅡ+image intensifier, the proximity focusing distance and the thickness of Na2KSb(Cs) multi-alkali photocathode of the GenⅡ+ image intensifier can be measured. The results provide an effective means to further increase photocathode sensitivity and resolution of the GenⅡ+ image intensifier.