SPECTROPHOTOMETRIC IMAGING IN ASTRONOMY WITH
KINETIC INDUCTANCE DETECTORS

The Microwave Kinetic Inductance Detector (MKID) was introduced by Day et al. (2003). They are composed of an LC circuit oscillating with a high quality factor (Q= f/Δf in the range 10⁴ – 10⁷ where f is the frequency of the oscillator and Δf its bandwidth) made with a superconducting material. They operate at temperatures of a few 100mK. An impinging photon breaks a cooper pair modifying the inductance, and thus the amplitude, the frequency, the phase of the oscillator. The oscillation frequency of the circuit is of the order of a few GHz, hence the name of Microwave. The read-out electronics monitors the oscillator, when the oscillation is modified it records the arrival of a photon. This event is tagged with the time of arrival and also with the energy of the photon, that is derived from the amplitude, frequency and phase of the new oscillation.