Confocal microscope and endoscope

Details Confocal microscope and endoscope Confocal microscope and endoscope

1995-04-20

1997-08-19

Ngo, John

Optical waveguides

With optical coupler

Switch

385115, 385 33, 385 45, G02B 626

Patent

active

056596421

DESCRIPTION:

BRIEF SUMMARY
This invention relates to a microscope and more particularly to a microscope using the principal of confocal microscopy.
The principal of confocal microscopy was disclosed in U.S. Pat. No. 3,013,467 to Minsky in 1957. With confocal microscopy, a point or spot (which my be diffraction-limited) within an object is illuminated and only light from that point is imaged, e.g. via a pin hole detector. By scanning the spot across a plane (e.g. with a translucent object) a clear image ("optical section") my be obtained.
International patent applications PCT/AU89/00298 and PCT/AU91/00129 describe the design of confocal microscopes which instead of a pin hole (or equivalent) of a conventional confocal microscope use an optical fiber or fiber bundle, thus allowing the distal end to be more freely mobile, transportable and miniaturisable.
The present invention relates to an improvement to confocal microscopes of the type described in the above mentioned International applications and which are particularly suited to produce images inside of the living body of animals or humans.
The invention may be said to reside in a confocal microscope comprising:
a light source;
an optical fiber bundle for receiving light from the light source and for transmitting the light to an object;
and for allowing light to return from the object through the optical fiber bundle;
switching means for selectively switching selected fibers in the optical fiber bundle so as to allow light to selectively be transmitted and returned through respective fibers in the optical fiber bundle; and
a detector for receiving returned light from the optical fiber bundle to enable an image of the object to be produced.
The use of switching means which enables the individual fibers in the bundle to be selectively switched to allow light to be transmitted through them enables selected fibers to be switched in sequence so that light is scanned across the focal plane on or within the object and light returning confocally from the object can be detected virtually instantaneously on its return from the object. Another alternative which could be particularly useful for real time imaging of fluorescent objects, is to generate an identical pattern of switching of the switch means which lags the original pattern so that light may be detected confocally a short time after it has illuminated the object. This is because peak fluorescence occurs at a time after illumination of an object.
Preferably the switching means comprises a plurality of switchable optical fiber or waveguide tree couplers, the plurality of tree couplers having a first end which receives light from a first light path and a plurality of second ends which are coupled to or integral with respective fibers of the fiber bundle.
In a further embodiment the switching means comprises a plurality of switches in the respective fibers of the optical fiber bundle.
In this embodiment of the invention an optical element is provided at an image end of the optical fiber bundle for simultaneously launching light to the individual fibers of the optical fiber bundle and for collecting return light from the optical fiber bundle.
Preferably a beam splitter or directional coupler is disposed proximal to the optical fiber bundle, for receiving light from the light source and transmitting the light to the optical fiber bundle, and for receiving return light from the optical fiber bundle and for transmitting the light to the light detector.
Preferably the first light path comprises one or more optical fibers. However, in other embodiments the first light path could comprise a beam path with or without beam steering optics rather than, or as well as at least one optical fiber.
Preferably a lens element or lens array is provided between the object and the distal end of the optical fiber bundle.
A further aspect of the invention concerns a scanning head which may be used in a confocal microscope.
This aspect of the invention may be said to reside in a scanning head for receiving light from a light source and for transmitting return

REFERENCES:
patent: 4410235 (1983-10-01), Klement et al.
patent: 4856863 (1989-08-01), Sampsell et al.
patent: 5037173 (1991-08-01), Sapsell et al.
patent: 5181134 (1993-01-01), Fatehi et al.
patent: 5448661 (1995-09-01), Takai et al.

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