Patent ID: 8817261

Claim:
A microscope comprising: an illumination source arranged to illuminate a sample zone with stimulation light that is absorbed by a marker, if present in the sample zone, and is emitted as four-wave mixing light, and a detector arranged to discriminate the four-wave mixing light in light emanating from the sample zone, wherein the illumination source comprises: a light source that emits a train of pulses of laser light, and an arrangement of parallel optical paths configured to received said train of pulses, and wherein said arrangement of parallel optical paths is configured to: create first, second and third versions of a single pulse of said train of pulses, and deliver said first, second and third versions of said single pulse to the sample zone such that the third version arrives at the sample zone after the second version and the second version arrives at the sample zone not earlier than the first version and not later than the first version by more than the dephasing time of the marker, and wherein the detector is configured to bring a fourth version of the said single pulse into interaction with the light emanating from the sample zone and the detector is configured to detect interference of the fourth version of said single pulse with four-wave mixing light triggered by the third version of said single pulse.