Miniature confocal optical head with integrated scanning and confocal imaging system using same

#1. Field of the Invention

#The present invention relates to a confocal optical head, in particular miniature, comprising integrated beam scanning means and a confocal imaging system equipped with said head.

#More precisely, the present invention relates to an optical head and a corresponding optical system, in which a field to be imaged in a specimen is scanned point by point by an excitation signal. This type of system makes it possible to obtain, by means of data processing, a confocal image constructed point by point in real time. The confocal character is obtained by means of spatial filtering making it possible to detect a return signal originating solely from the excited point of the specimen taking the same optical path as the excitation signal.

#The present invention will be better understood and other advantages will appear more clearly in light of the following description of embodiments, a description made with reference to the attached drawings in which:

#FIG. 1 is a general diagram of an example of a fibre-type confocal imaging system using the miniature head according to the invention;

#FIG. 2 is a side cross-section of a miniature head according to a first embodiment;

#FIG. 1 schematically represents a fibre-type confocal imaging system which can include a miniature head according to the invention.

#The system comprises a source 1, for example a laser source, capable of emitting an excitation signal with a wavelength capable of generating in a specimen a return fluorescence or backscattering signal, said signal being conveyed by a first single-mode optical fibre 2a to coupling means 3, for example a 50/50 fibre coupler, provided in order to direct the excitation signal originating from the source 1 into a single-mode optical fibre 2b at the end of which the miniature optical head 4 according to the invention is situated and in order to direct the return signal originating from the excited site towards detection means 5, for example a photodetector, using a third single-mode optical fibre 2c. The system comprises electronic control, command and synchronization means 6, making it possible to control the source 1, the scanning means of the optical head 4 and the detection means 5, in a synchronized manner, in order in particular to know the location of the signal in the specimen in order to allow the construction of an image in real time. The system moreover comprises electronic means 7, of amplification, forming and A/D conversion of the signal detected by the detection means 5, data-processing means 8 comprising an acquisition card and a graphics card and means of displaying 9 the images obtained.

#This system operates overall in the following manner: the miniature optical head 4 is brought into contact with a specimen to be analyzed, for example via the operating channel of an endoscope. The source 1 sends an excitation signal with a chosen wavelength into the portion of fibre 2a. The coupler 3 directs the excitation signal into the portion of fibre 2b guiding the signal into the optical head 4 where it is scanned and focused on an analysis surface (or analysis field) in a plane of the specimen perpendicular to the optical axis defined by the optical fibre 2b, at a given depth in the specimen. A return signal originating from the scanned surface in the specimen follows the reverse path of the excitation signal as far as the coupler 3: it is picked up by the optical means of the optical head 4, recoupled in the portion of fibre 2b, then directed by the coupler 3 into the portion of fibre 2c towards the detector 5. The signal detected is amplified and converted to a digital signal, then subjected to data-processing in order to finally constitute an image element displayed in real time.