Enemy or foe is an individual or a group that is seen as forcefully adverse or threatening. The concept of an enemy has been observed to be basic for both individuals and communities.
A diffractometer (pronunciation: di-frak-'tÃ¤-m&-t&r) is a measuring instrument for analyzing the structure of a material from the scattering pattern produced when a beam of radiation or particles (such as X-rays or neutrons) interacts with it. Principle
For calibrating instruments used to measure the power or energy emitted by a laser, specially designed standards consisting of calorimeters, pyrometers, thermal radiometers and diode traps have been used for many years. Low-level laboratory standards are realized using solid-state photodetectors.