Structured illumination microscopy using micro-pixellated light-emitting diodes

Structured illumination is a flexible and economical method of obtaining optical sectioning in wide-field microscopy [1]. In this technique the illumination system is modified to project a single-spatial frequency grid pattern onto the sample [2, 3]. The pattern can only be resolved in the focal plane and by recording images for different transverse grid positions (or phases) an image of the in-focus parts of the object can be calculated. Light emitting diodes (LEDs) are becoming increasingly popular for lighting and illumination systems due to their low cost, small dimensions, low coherence, uniform illumination, high efficiency and long lifetime. These properties, together with recent developments in high brightness, ultraviolet operation and microstructured emitter design offer great potential for LEDs as light sources for microscopy. In this paper we demonstrate a novel structured illumination microscope using a blue micro-structured light emitting diode as the illumination source. The system is potentially very compact and has no-moving-parts

Passively mode locked c.w. dye lasers operating from 490 nm to 800 nm

Passively mode locked c.w. dyes lasers now represent an important source of femtosecond optical pulses tunable through the visible and near infra red spectrum. Pulses as short as 70 fs have been obtained from dispersion-optimised CPM cavity configurations using active/passive dyes other than the standard combination of Rhodamine 6G and DODCI.Les lasers à colorant continu à blocage de mode passif représentent actuellement une importante source d'impulsions optiques femtosecondes accordables dans le spectre visible et proche-infrarouge. Des impulsions aussi courtes que 70 fs ont été obtenues, avec des configurations de cavités à collisions d'impulsions à dispersion optimisée, par l'utilisation de colorants actifs/passifs autres que la combinaison standard Rhodamine 6G et DODCI

Microstripe-array InGaN light-emitting diodes with individually addressable elements

High-performance InGaN light-emitting diodes consisting of 120 side-by-side and individually addressable microstripe elements have been successfully fabricated. Each stripe in these devices is 24 pm in width and 3600 mu m long, with a center-to-center spacing between adjacent stripes of 34 mu m. The emission wavelengths demonstrated range from ultraviolet (UV) (370 nm) to blue (470 nm) and green (520 nm). The devices show good uniformity and performance due to finger-pattern n-electrodes running between adjacent stripes. In the case of the UV devices for example, turn-on voltages are around 3.5 V and continuous-wave output powers per stripe similar to 80 mu W at 20 mA. A major feature of these devices is their ability to generate pattern-programmable emission, which offers applications in areas including structured illumination wide-field sectioning optical microscopy

Improved sectioning in a slit scanning confocal microscope

We describe a simple implementation of a slit scanning confocal microscope to obtain an axial resolution better than that of a point-scanning confocal microscope. Under slit illumination, images of a fluorescent object are captured using an array detector instead of a line detector so that out-of-focus light is recorded and then subtracted from the adjacent images. Axial resolution after background subtraction is 2.2 times better than the slit confocal resolution, and out-of-focus image suppression is calculated to attenuate with defocus faster by 1 order of magnitude than in the point confocal case