Scanning near field optical microscope

A high resolution observation apparatus comprising:

• a light emitting source for emitting an incident light to be incident on a sample so that an evanescent light is projected from the sample in response to the incident light;
• a probe disposed proximate a surface of the sample and having a narrow tip for scattering the evanescent light projected by the sample;
• an evanescent light detector disposed proximate the probe tip for detecting the evanescent light scattered by the probe tip and outputting a corresponding signal;
• a position control system responsive to a control signal for supporting and moving at least one of the probe and the sample in a first direction to control the distance therebetween in the first direction and for causing relative scanning movement therebetween in a plane perpendicular to the first direction;
• and a servo circuit responsive to the output signal of the light detector for producing the control signal to control the position control system to maintain the detected evanescent light constant.

A high resolution observation apparatus comprising:

• an optical device having a surface on which a sample to be observed is disposed;
• an optical source for generating an incident light of a predetermined wavelength to be incident to the sample through the optical device at a total reflection angle;
• a probe having a sharpened tip for scattering a sample light projected from the sample surface in response to the incident light;
• an optical detecting system for detecting the sample light scattered by the probe;
• a position control unit for moving one of the probe and the sample in the XY plane to scan the sample over a two-dimensional area to be observed;
• and
• a Z-axis control unit for positioning the probe at a distance from the sample surface in the Z direction close enough to locally scatter sample light projected from a minute region of the sample and for controlling the Z-direction distance between the probe and the sample surface so as to keep a positioning signal detected by the optical detecting system constant during a course of scanning the sample surface over the two-dimensional area to be observed.