Author Affiliations
Abstract
1 School of Electronic Engineering, Xi’an University of Post & Telecommunications, Xi’an 710121, China
2 State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi’an 710119, China
Li ions affect the upconversion efficiency by changing the local crystal field of the luminescent center. Herein, in order to improve the upconversion efficiency of NaYF4:Yb3+/Eu3+, a series of NaYF4:Yb3+/Eu3+ micro-particles with different Li+ doping concentrations were synthesized by the hydrothermal synthesis method, respectively. Firstly, the structure and morphology of NaYF4:Yb3+/Eu3+ upconversion micro-particles (UCMPs) with different doping concentrations were analyzed by X-ray diffraction and a scanning electron microscope (SEM). SEM results show that the UCMPs are not only highly crystallized, but also have hexagons with different Li+ concentrations of NaYF4:Yb3+/Eu3+. X-ray diffraction shows that the crystal field around Eu3+ changes with the increase of Li+ concentration. Then, the fluorescence spectrum of NaYF4:Yb3+/Eu3+ was studied under the irradiation of a 980 nm laser. The results show that the fluorescence intensity of NaYF4:Yb3+/Eu3+ with 2% Li+ is the strongest, which is twice the intensity of NaYF4:Yb3+/Eu3+ without Li+. Finally, the fluorescence imaging analysis of NaYF4:Yb3+/Eu3+ with 2% Li+ concentration was carried out. The UCMPs are used to screen printing to evaluate the imaging effect on different sample surfaces. The results show NaYF4:Yb3+/Eu3+ (with 2% Li+) has great application prospects in anti-counterfeiting recognition.
upconversion micro-particles hydrothermal synthesis anti-counterfeiting identification screen printing Chinese Optics Letters
2020, 18(11): 110501
1 西安邮电大学电子工程学院, 陕西 西安 710121
2 中国科学院西安光学精密机械研究所光谱成像技术重点实验室, 陕西 西安 710119
全息凹面光栅光谱仪具有平谱面、小型化、大孔径、高分辨率等优点。首先从信息光学的角度推导了全息凹面光栅的成像公式,在垂直于狭缝和平行于狭缝的平面上系统分析了全息凹面光栅光谱仪的成像性能;在垂直于狭缝的平面上,全息凹面光栅光谱仪具有良好的平谱面性;在平行于狭缝的平面上,全息凹面光栅光谱仪克服了传统平面光栅的谱线弯曲和色畸变,实现了谱线平直成像;此外指出全息凹面光栅光谱仪固有的弧矢场曲对视场扩展的限制。然后根据理论分析结果提出了结构对称消场曲的全息凹面光栅光谱仪的设计思想,利用ZEMAX软件优化设计了像差补偿型全息凹面光栅光谱仪。在保证相对孔径F#=3、光谱分辨率为20 nm/mm、空间分辨率小于25 μm等技术指标不变的前提下,设计了狭缝长度为0.4 mm的传统单球面镜全息凹面光栅光谱仪和狭缝长度为8 mm的像差补偿型全息凹面光栅光谱仪。结果表明,改进后的像差补偿型全息凹面光栅光谱仪成功地将视场扩大为单球面镜全息凹面光栅光谱仪的20倍。
光谱学 光谱仪 对称设计 全息凹面光栅光谱仪 宽场 平谱面
1 中国科学院西安光学精密机械研究所 光谱成像技术实验室,陕西 西安 710119
2 西安邮电大学 电子工程学院,陕西 西安 710121
3 中国科学院大学,北京100049
切尔尼-特纳(Czerny-Turner, C-T)光谱仪是光栅光谱仪中常用的光谱仪器。其结构紧凑,无非球面镜,常被用于单色仪和光谱辐射计中。对于成像光谱仪,像散是影响其空间分辨和光能利用的主要像差。就非平行光束光栅照明像散校正方法进行了理论分析和实验验证,提出会聚和发散光栅照明C-T成像光谱仪都可以进行像散校正,其根本取决于光栅入射角和衍射的余弦平方比大于或小于1,大于1对应发散照明消像散,小于1则对应会聚照明消像散。
会聚照明 C-T成像光谱仪 像散 convergent illumination C-T imaging spectrometer astigmatism