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.
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.
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Fiber-Optic Illumination for Microscope
(reference NPO19484) is currently available for download from the TSP library.
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Overview
The document presents a novel fiber-optic illumination system for microscopes, developed by Hiroshi Kadogawa at NASA's Jet Propulsion Laboratory (JPL). This innovative approach addresses the limitations of traditional Köhler-type vertical illumination systems, which often rely on complex components like beam splitters and lenses. The new system utilizes an optical fiber to deliver light directly to the edge of the microscope objective back lens, allowing for efficient and effective illumination of opaque specimens.
One of the primary challenges in microscopy is illuminating opaque samples, which cannot be effectively back-illuminated due to their nature. Conventional vertical illuminators often suffer from significant light loss, transmitting only about 25% of the projected light to the observer, while the remaining 75% becomes stray light. Additionally, these systems tend to be bulky and cumbersome, complicating the microscopy process. The fiber-optic system overcomes these issues by providing high-intensity vertical illumination without the need for bulky attachments, making it a compact and cost-effective solution.
The fiber-optic illumination method is particularly advantageous for examining metallic and opaque samples, which are common in fields such as metallurgy and semiconductor research. The design allows for easy integration into existing microscope systems, either by slightly modifying commercial units or by incorporating the fiber directly into the microscope objective lens with a detachable connector. This flexibility ensures that traditional microscope bodies can be adapted for vertical illumination at a low cost.
Tests have shown that the alignment of the fiber is not critical, as it is not imaged at the specimen, further simplifying the setup process. The document emphasizes the potential for commercial use of this technology, highlighting its effectiveness in providing clear and intense illumination for various applications in microscopy.
In summary, this fiber-optic illumination system represents a significant advancement in microscopy technology, offering a simpler, more efficient, and cost-effective alternative to traditional illumination methods. The invention is currently owned by NASA, and a patent application has been filed, indicating its potential for future commercial development.
