CONTEXT

Existing devices do not provide information on the phase of the evanescent wave. Some characteristics of the object can not be measured by these devices.

TECHNICAL DESCRIPTION

The invention is a detection device for imaging of an object including:

– A laser cavity arranged to deliver an original light signal at a wavelength of origin to the subject so as to generate an evanescent wave on the surface of the object;

– Means of processing arranged to convert evanescent waves into a progressive signal with output wavelength;

– Means of re arranged to inject the progressive signal in the laser cavity in order to generate disturbances within the laser cavity between the progressive signal and the signal light of origin;

– Means of detection arranged to detect disturbances in order to determine at least one physical characteristic of the object.

BENEFITS

The invention improves the extent of the evanescent wave generated on the surface of the object by changing the wavelength of the progressive signal injected into the laser cavity wich is different from the original. Disturbances in the form of dynamic heterodyne beats are measured.

INDUSTRIAL APPLICATIONS

The invention associated with scanning for microdots can be advantageously used in a SNOM microscope, acronym for « Near Field Scanning Optical Microscopy », or microscopy detection of evanescent field.

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