Spectra originated in the 17th century, and in 1666, physicist Newton conducted his first experiment on the dispersion of light. He introduced a beam of sunlight into the darkroom and let it pass through a prism. On the white screen behind the prism, he saw seven colors of light - red, orange, yellow, green, blue, indigo, and purple - scattered in different positions. This phenomenon is called spectrum. In 1802, British chemist Wollaston discovered that the solar spectrum was not a perfect rainbow, but rather cut apart by some black lines. In 1814, German optical instrument expert Fraunhofer studied the relative positions of black spots in the solar spectrum and used a slit device to improve the imaging quality of the spectrum by plotting the main black lines in the spectrum. In 1825, Talbot studied the spectra of sodium and potassium salts on alcohol lamps and pointed out that the red spectrum of potassium salts and the yellow spectrum of sodium salts were both characteristics of this element. By 1859, Kirchoff and Bunsen had designed and manufactured a sophisticated spectroscopic device to study the spectra of metals. This device was the world's first practical spectroscopic instrument, capable of studying the spectral lines of various metals in flames and electric sparks, thus establishing a preliminary foundation for spectroscopic analysis.

The transition from measuring the absolute intensity of spectral lines to measuring the relative intensity of spectral lines laid the foundation for the development of spectral analysis methods from qualitative analysis to quantitative analysis, gradually leading them out of the laboratory and applied in the industrial sector. After 1928, as spectroscopic analysis became an industrial analytical method, spectroscopic instruments developed rapidly, making progress in improving the stability of excitation light sources and enhancing the performance of spectroscopic instruments themselves.

The early excitation light source was flame, and later developed into simple applications of arc and electric spark as excitation light sources. In the 1930s and 1940s, improved controllable arc and electric spark were used as excitation light sources to improve the stability of spectral analysis. The development of industrial production and the advancement of spectroscopy have promoted the further improvement of optical instruments, while the latter has a counter effect on the former, promoting the development of spectroscopy and industrial production.

In the 1960s, with the development of computer and electronic technology, photoelectric direct reading spectrometers began to rapidly develop. In the 1970s, almost 100% of spectroscopic instruments were controlled by computers, which not only improved analysis accuracy and speed, but also achieved data processing of analysis results and automated control of the analysis process.

Optoelectronic direct reading spectroscopic analysis is the process of using high temperatures from an arc (or spark) to directly vaporize and excite the elements in a sample from the solid state, resulting in the emission of characteristic wavelengths of each element. After being separated by a grating, the characteristic spectral lines of these elements are arranged according to the wavelength. The characteristic spectral lines of these elements pass through the exit slit and enter their respective photomultiplier tubes, and the optical signal is converted into an electrical signal. The electrical signal is integrated and analog-to-digital converted by the instrument's control measurement system, Then processed by a computer and printed out the percentage content of each element.

From a technical perspective, it can be said that there is currently no instrument more effective than direct reading spectroscopy for rapid analysis in front of a furnace. So smelting, casting, and other metal processing enterprises around the world all use this type of instrument, making it a routine analytical method. [1]