Encoders play a crucial role in the precise measurement of angular positions, and when it comes to spectrographs, they enable accurate wavelength calibration and dispersion control. These devices consist of optical glass discs that feature precisely engraved patterns or gratings on their surfaces. The patterns are typically created using advanced lithography techniques to ensure high resolution and fidelity. As the glass disc rotates, light passes through the patterned regions, and the resulting modulations in intensity or wavelength are detected by sensors. By precisely tracking the rotational position of the glass disc, encoders provide essential feedback for spectrographs, allowing for precise determination of wavelengths and facilitating the calibration and alignment of spectral data. Through the harmonious interaction between encoders and optical glass discs, spectrographs can achieve exceptional accuracy and reproducibility, enabling scientists to explore the intricacies of light and unravel the secrets of the universe at the atomic and molecular levels.