Final answer:
Techniques to reduce reflections with optometers include changing the incidence angle of light, anti-reflective coating application on lenses for destructive interference at a specific wavelength, and using adaptive optics to correct for atmospheric effects in telescopes.
Step-by-step explanation:
To reduce unwanted reflections with optometers, several techniques can be employed. One common approach is to alter the incidence angle of the light source, like a camera flash, so that reflections do not directly bounce back into the lens. For example, tilting an object, such as a pair of glasses, can change the angle of reflection to avoid flash glare. In the case of optical instruments, a thin film of anti-reflective coating is applied to one of the lenses within a camera lens system.
This coating is designed to cause destructive interference at a specific wavelength to minimize reflections. The thickness of this coating is calculated based on the wavelength and the indices of refraction of both the lens and the coating material. For a camera lens with a glass index of refraction of 1.68, and a coating index of 1.28, the minimum layer thickness to reduce reflection at 640 nm can be determined by applying thin-film interference equations. In addition, the use of adaptive optics can correct for atmospheric turbulence, improving image quality in telescopes.