Biomedical subjects

C W See

Publications and source records attributed to C W See.

4 recordsLinked to original sources

PubMed2004

High-resolution wide-field surface plasmon microscopy.

This paper describes the application of a Köhler illuminated high-resolution wide-field microscope using surface plasmons to provide the image contrast. The response of the microscope to a grating structure in both the Fourier and the image planes is presented to demonstrate image formation by surface waves. The effect of spatial filtering in the back focal (Fourier) plane to enhance image contrast is described. We also discuss how the surface wave contrast mechanism affects the imaging performance of the microscope and discuss factors that can be expected to lead to even greater improvements in lateral resolution and sensitivity.

Journal Article↗

PubMed2004

Quantitative optical microscope with enhanced resolution using a pixelated liquid crystal spatial light modulator.

This paper presents a brief account of a novel optical microscope, which combines the advantages of two well-known techniques, namely phase contrast and phase stepping, to provide high contrast imaging and precision measurements. The inclusion of a programmable liquid crystal spatial light modulator provides for the phase stepping required, while also allowing flexibility for future improvements. The results shown reveal an important aspect of the system to facilitate quantitative sample measurements, with an enhancement of optical resolution compared with conventional optical imaging systems.

Journal Article↗

PubMed1988

High-precision tilt stage for the high-voltage electron microscope.

The high-voltage electron microscope is used to study thick samples (0.25 to several micrometers) to obtain three-dimensional information at ultrastructural resolution. Three-dimensional image reconstructions are often employed to extract, process and display this information. The sets of images used to form reconstructions must be recorded for precisely known specimen-beam orientations, especially if tomographic methods are employed. The design and operation of a precision (+/- 0.06 degrees) single-tilt stage to support this type of imaging is reported. All motions including two translations, height adjustment and tilting are accomplished via a single objective lens entry port. The specimen rod is supported on two rubber gaskets for vibration isolation, and motorized precision micrometers with encoder readouts for position monitoring drive the motions. The stage is stable to 0.6 nm for at least 16 s and is capable of tilt angles of +/- 70 degrees.

Microscopy, Electron↗

PubMed1981

Design and operation of a differentially pumped environmental chamber for the HVEM.

A differentially pumped environmental chamber, or DIFPEC, has been developed for the AEI EM7 1.2 MV HVEM. The chamber is suitable for imaging and diffraction studies and is capable of operation at pressures approaching one atmosphere. Any mixture of gases can be used including water vapor supplied from an internal reservoir. Correct operation is demonstrated by measurements of temperature, pressure, and water consumption. High resolution (0.2 nm) diffraction patterns were recorded from unfixed, unstained, fully hydrated catalase crystals. This is good functional test of DIFPEC operation and specimen preparation because catalase disorders irreversibly of exposed to less than 95% relative humidity. High- and low-angle diffraction patterns were recorded from unfixed, unstained, fully hydrated rat hemoglobin crystals. All patterns were recorded using 10-4 C/cm2. Whole cell mounts prepared in different ways were imaged and show that 5.3 kPa of nitrogen gas has no detrimental effect on image contrast or resolution. The column vacuum and differentially pumped volume pressure were measured for a number of pumping configuration, as well as for several gases and pressures in the specimen volume. The pressure in the high vacuum portion of the objective lens gap is conductance-limited when the DIFPEC is in place.

Animals↗