現今光電產業的蓬勃發展，產生了許多種類的可見光光源。在分析光源的頻譜時，一般都借助貴重的頻譜分析儀，因此使學生較不易接觸進而瞭解光譜的特性。本研究利用光柵作演示教學，成功分析出雷射二極體的波長，其誤差值小於2％以內，亦可利用光柵來分析各種LED的波長並得到白光LED的波長範圍約為421nm至668nm。

The fast expansion and development of optoelectronic industry produce many types of visible light sources. Using spectrum analyzer to analyze the light source spectrum is easy but expensive. Thus making it difficult for students to understand the spectral features. In this study, we successfully use grating to analyze the wavelength of laser diode, the wavelength percentage error is less than 2%; grating can also be used to analyze wavelength of different LEDs, getting white LED wavelength ranging from 421 nm to 668 nm.