The width of the slit sets the balance between spectral resolution and light throughput, so it's at the core of how accurate and high-quality any spectroscopic measurement can be. They are usually made with high precision, often with laser material processing in some resistant metal such as stainless steel, molybdenum or tungsten. A larger width will increase the optical power available for analysis, which can reduce the time needed to acquire an. An optical power meter (OPM) measures the power levels of light signals in devices that transmit data or power using light. The term "optical power meter" may sound generic, but in popular usage, it specifically implies a fiber optic power meter. For light power measurements outside the field of.