Optical techniques refer to methods that utilize light to analyze, manipulate, or measure various properties of materials and systems. These techniques can include microscopy, spectroscopy, and interferometry, which help scientists and engineers observe structures at different scales and understand the composition of substances. These methods are widely used in fields such as biology, chemistry, and physics. For example, optical microscopy allows researchers to view cells and tissues in detail, while spectroscopy helps identify chemical compounds by analyzing light absorption and emission. Overall, optical techniques are essential tools in scientific research and industrial applications.