Flat mirrors sometimes called plane mirrors, are one of the most commonly used optical components. Ideally a flat mirror should reflect 100% of the light incident on it, without altering the wavefront shape. To select a mirror, optical coating, reflective properties are dependent on wavelength, angle of incidence, and polarization, it is important to consider the application. The flatness of the mirror substrate and its mechanical and thermal stability are important.
They are used for projection TV, document projection instrument, laser printing, electrograph etc.