joyce
Leerling bovenbouw havo-vwo - maandag 10 maart 2003
Antwoord
Op onderstaande website staat:
"The instrument transmits a light beam (wavelength 550 nm), to which is applied a modulation of approximately 30 MHz (10 m), i.e. the light is intensity-modulated. The beam is directed onto a reflector at the distant station, from which it is reflected back to the instrument. The incoming light is received by a photo-multiplier (hence converted to an electrical signal) and the difference in phase between the transmitted and received modulations is measured."