Confocal fluorescence microscopes are a promising imaging tool in medical diagnostics due to their capability to
selectively survey cross-sections of individual layers from ‘thick’ samples. Non-invasive depth resolved investigation of
neoplastic skin disorders is one example among other applications. However these microscopes are at present uncommon
in medical practice. This is due to their main application area in research. The instruments dealt with here are generally
complex, stationary units and are accordingly cost-intensive.
It is for this reason, that we have designed a robust and portable MEMS based confocal fluorescence microscope with a
field of view of 0.6mm x 0.6mm. This has been made possible by the integration of a 2D micro scanner mirror
developed at Fraunhofer IPMS. A variable acquisition depth of cross-sectional images of the fluorescence specimen is
enabled by an integrated z-shifter.
With the use of commercially available optics an optical demonstrator set up has been realized. To characterize and to
demonstrate the ability of this system test measurements were performed. The resolution of the microscope is better than
228 lp/mm determined by 1951 USAF resolution test target. Images of various biological samples are presented and
optical sectioning capabilities are shown. A comparison of the measured with the predicted system performance will be
given.
Although confocal fluorescence laser scanning microscopy is a widely used technique in biology, these microscopes are
at present uncommon in medical diagnostics. However laser scanning fluorescence microscopy is a non-invasive
imaging technique that allows depth resolved investigations of skin disorders. High costs and large outline are factors
which impede the establishment of this technology in medical practice. To overcome this obstacle, we have designed a
portable confocal laser scanning fluorescence microscope and realized an optical demonstration set-up, offering a field of
view of 500μm x 500μm. The microscope is based on a dual axis MEMS mirror where the confocal character of the
system resides in the use of the same path for illumination and detection with the rejection of out-of-focus light by a
pinhole. Illumination is provided by a laser and the fluorescence light is separated from the illumination light by a filter,
before being detected. The ability to perform cross-sectional imaging of fluorescence specimen will be given by an
integrated z-shifter.
Although skin is easily accessible to optical methodologies, biopsies are at present a widely used procedure in
dermatologic diagnostics. However fluorescence confocal laser scanning microscopy (F-LSM) is a non-invasive imaging
technique that allows depth resolved investigations of inflammatory and neoplastic skin disorders in vivo and at high
resolution. By applying substances onto or into the epidermis F-LSM is well suited to obtain information regarding the
morphological structures of the skin down to a hundred micrometers below the skin surface. Compared to conventional
light microscopy of histological sections this optical method has a clear advantage in the case of kinetic measurements.
To this end, we have designed a portable confocal fluorescent microscope for future dermatologic studies, offering a
field of view of 600μm x 600μm. Based on a dual-axis MEMS mirror (Fraunhofer IPMS, Germany) the confocal
character of the system resides in the use of the same path for illumination and detection with spatial filtering of the
signal collected from the subsurface analysis plane. Illumination is provided by a 488nm laser and the backscattered
fluorescence light is separated from the illumination light by a filter, before being detected behind the pinhole. To
reconstruct the image the measured intensity and position information is correlated. The ability to perform crosssectional
imaging in the skin will be given by an integrated z-shifter.
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