In a simple but very effective method for providing intense illumination of an opaque specimen under a microscope, light is supplied via an optical fiber. This system eliminates the need for traditional Köhler-type vertical illumination system components, such as beam splitters and lenses, and is easily adaptable to vacuum environments. The output end of the fiber is placed at the edge of the microscope objective back lens (see figure), near the pupil. The light from the fiber passes down through the objective lens, which concentrates the light onto the specimen.

Tests indicate that alignment of the fiber is not critical since the fiber is not imaged at the specimen. The microscope tube may be a slightly modified commercial off-the-shelf unit, or the fiber may be integrated into the microscope objective lens with a detachable fiber connector so that completely unmodified microscope bodies can be adapted to vertical illumination at low cost. This fiber-optic illumination scheme is expected to be especially useful in microscopy of semi-conductor or metallurgical specimens and other opaque objects, as well as in biomedical microscopy.

Light Is Supplied from an external lamp via an optical fiber, using the microscope objective lens to focus the light onto the specimen. This simple illumination scheme is relatively inexpensive and, in many cases, more effective than are conventional vertical-illumination schemes that involve complex and bulky optical systems with beam splitters, which waste light.

This work was done by Hiroshi Kadogawa of Caltech for NASA's Jet Propulsion Laboratory.

This invention is owned by NASA, and a patent application has been filed. Inquiries concerning nonexclusive or exclusive license for its commercial development should be addressed to

the Patent Counsel
NASA Management Office-JPL; (818) 354-2240

Refer to NPO-19484.

This Brief includes a Technical Support Package (TSP).
Fiber-Optic Illumination for Microscope

(reference NPO19484) is currently available for download from the TSP library.

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Photonics Tech Briefs Magazine

This article first appeared in the November, 2001 issue of Photonics Tech Briefs Magazine.

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