Naked-eye observations of visible spectra using a transmission-grating-based spectrometer, with the spectral resolution of 0.2nm @ 550nm, are reported in this article. The resultant accuracy of the wavelength readout with the naked-eye is better than 1nm. The diffraction angles are precisely confirmed when the virtual diffraction image of the entrance slit (line spectrum) are collinear with two collimating slits. Furthermore, a converging lens is used to magnify the tiny light source (or narrow slit), and receive more radiant flux, with no effect on the accuracy of the spectral measurement. The spectrometer provides a good training aid for college students because (1) it is a low cost and handy demo experiment; (2) it has no optoelectronic sensor, it is completely naked-eye observation; (3) it helps students intuitively understand the diffracting and imaging processes; (4) the resolving power meets the requirements for teaching purposes.

本文报道了使用基于透射光栅的光谱仪对可见光谱的肉眼观察，光谱分辨率为 0.2nm @ 550nm。肉眼读取波长的最终精度优于1nm。当入口狭缝（线光谱）的虚拟衍射图像与两个准直狭缝共线时，可以精确地确定衍射角。此外，会聚透镜用于放大微小的光源（或窄缝），并接收更多的辐射通量，而不会影响光谱测量的准确性。该光谱仪为大学生提供了很好的培训辅助，因为（1）它是一种低成本且方便的演示实验；(2)无光电传感器，完全肉眼观察；(3) 帮助学生直观地理解衍射和成像过程；(4)分辨率满足教学要求。