Microspectroscopy device

A microspectroscopy device comprising:

• a light source for outputting an excitation beam for exciting a light emission from a sample;
• an objective lens for illuminating the sample with the excitation beam;
• an imaging device for detecting the light emission from the sample excited by the excitation beam;
• a defocus-sensing beam having a wavelength or an optical axis different from a wavelength or an optical axis of the excitation beam incident on the objective lens;
• a stage for moving the sample in a direction of an optical axis of the objective lens;
• a monitoring imaging device for observing a shape of an image formed on the sample by the defocus-sensing beam having passed through the objective lens;
• and
• a controller for detecting a direction and an amount of defocus from the shape of the image of the defocus-sensing beam and for sending a feedback control signal so as to move the stage to a focus position of the objective lens,
• the defocus-sensing beam includes at least two or more defocus-sensing beams,
• at least one of the at least two or more defocus-sensing beams is focused by the objective lens at a position closer to the objective lens than a position where the excitation light beam is focused by the objective lens, and at least one of the at least two or more defocus-sensing beams is focused by the objective lens at a position farther from the objective lens than the position where the excitation light beam is focused by the objective lens, and
• the microspectroscopy device further comprises a monitoring imaging device for observing the defocus.