Yuguo Tang

A new type of wide spectral coverage echelle spectrometer design for ICP-AES

The inductively coupled plasma atomic emission spectrometry (ICP-AES) has always attracted great interest and is widely used for routine elemental analysis. While one drawback of this technique is the fact that conventional Czerny- Turner spectrographs in combination with CCD cameras are very limited either in terms of spectral resolution or in terms of simultaneously detectable spectral range. A cross-dispersion system with echelle grating and prism has therefore been developed, and the spectral image is directed by large area charge coupled device (CCD). This configuration meets the needs of atomic emission spectroscopy well, since it has many benefits including high resolving power, spectral coverage, high sensitivity, and high optical throughput. While, because the limitation of the development of detectors, it is difficult to complete wide spectral coverage measurement. Due to the improvements in optical design, this system can detect the wide spectral coverage from 180nm to 900nm simply by rotating the prism, and these two ranges are 180nm- 260nm and 210nm-900nm, with a high resolution 0.009nm@200nm. The detection of different elements only needs to choose appropriate wavelength coverage, thus lots of elements can be analyzed within quite short time. The novel optical design of this instrument is presented in this paper and its merits are discussed. The optical spectral resolution and the precision of wavelength calibration are found to be satisfactory and within design goals. Experiments show that the ICPAES with echelle spectrometer is available to detect multiple elements within a short time correctly, and the wavelength precision is better than 0.01nm.

Application of photoresist melting method to the fabrication of holographic grating

A new technique of reducing surface roughness of photoresist grating is presented. In this paper, photoresist melting method, which is low-cost, short-period and easy realization, is presented. In addition, the influence of photoresist melting on the groove profile of the photoresist grating is investigated. Experimental results show that the surface roughness reduces due to surface tension, when developed photoresist is heated to be melting state by this method. In experiment, when the melted photoresist grating is etched by ion beam, the surface relief grating possessing preferable groove profile is obtained on K9 glass substrate, then the surface is evaporated by aluminum using vacuum evaporation, holographic grating with preferable groove profile is successively fabricated.