Microscope and observation method

A microscope comprising:

• at least one light source that emits light;
• a lens that focuses light emitted from the light source and irradiates a sample with the light emitted from the at least one light source;
• and
• at least one detector that detects signal light generated by a multi-photon transition process in the sample when the sample is irradiated with the light emitted from the at least one light source, wherein
• the light emitted from the at least one light source is applied to the sample with an intensity changed to obtain a nonlinear region in which an intensity of the light emitted from the at least one light source and an intensity of the signal light have a nonlinear relation due to occurrence of saturation or nonlinear increase generated by a non-linear optical effect when the light emitted from the at least one light source has a maximum intensity,
• the sample is irradiated with two light beams having different wavelengths,
• the two light beams are modulated with the same modulation frequencies and the same phase,
• the signal light from the sample is generated by an m-photon reaction (m is a natural number of 2 or more) of the two intensity-modulated light beams, and
• the detector detects the signal light according to the intensity of the light emitted from the at least one light source and extracts a (m+1) or higher-order harmonic component for the modulation frequency to perform observation based on one of a saturation component and a nonlinear increase component of the signal light.

A microscope comprising:

• at least one light source that emits light;
• a lens that focuses light emitted from the light source and irradiates a sample with the light emitted from the at least one light source;
• and
• at least one detector that detects, as the signal light, at least one of reflection light, transmitted light, and scattered light generated with the same wavelength as that of the light from the light source upon application of the light emitted from the at least one light source to the sample, wherein
• the light emitted from the at least one light source is applied to the sample with an intensity changed to obtain a nonlinear region in which an intensity of the light emitted from the at least one light source and an intensity of the signal light have a nonlinear relation due to occurrence of saturation generated by a non-linear optical effect of the signal light when the light emitted from the at least one light source has a maximum intensity, and
• generation of optical harmonics due to other optical effects including a higher-order nonlinear optical effect causes the signal light serving as at least one of the reflection light, transmitted light, and scattered light to be saturated to perform observation based on a saturation component of the signal light.

An observation method that irradiates a sample with light emitted from at least one light source and observes the sample, the method comprising:

• focusing the light emitted from the at least one light source and irradiating the sample with the light emitted from the at least one light source to generate , as the signal light, at least one of reflection light, transmitted light, and scattered light having the same wavelength as that of the light from the light source;
• changing the intensity of the light emitted from the at least one light source such that the signal light from the sample has a nonlinear region in which an intensity of the light emitted from the at least one light source and an intensity of the signal light have a nonlinear relation due to saturation of the signal light generated by a non-linear optical effect when the light emitted from the at least one light source has a maximum intensity;
• and
• generating optical harmonics due to other optical effects including a higher-order nonlinear optical effect to cause the signal light serving as at least one of the reflection light, transmitted light, and scattered light to be saturated to perform observation based on a saturation component of the signal light.