Background

FLUOLED for transmitted light fluorescence
FLUOLED® Easy is designed to attach to a standard bright field microscope, where halogen white light function remains intact; this means transmitted light observation is possible without major changes in the optical configuration. FLUOLED® Easy is ideal for those applications on transparent samples where low to medium power lenses are used and cost savings on optics are important. The kit is designed to attach to a standard bright field microscope and does not change the characteristics of the microscope.

The adaptor (1) is clamped over the microscope base and holds the light emitting diode (2) inside. A 45 mirror (3) reflects light emitted by the diode through the condenser on the sample. Form and shape of adaptor may change from figure. Fluorescence emitted by the sample is filtered by an optical filter (4) before reaching the observer. A knob on the filter carrier allows to select the position: when the knob is pushed in, LED light is automatically switched on. When the knob is pulled out, LED light is automatically switched off in order to allow transmitted white light observations. A coloured reference mark on the knob helps to identify which position is selected.

In transmitted light fluorescence the condenser creates a specific power density of light on the sample, which is a fixed value. Objectives with smaller numerical aperture typically have a larger diameter of the front lens and therefore are able to capture more light emitted by the sample. Furthermore conveniently priced objectives have less glass inside allowing a very high signal intensity at low magnification (10x, 20x). At 40x or 50x still very good illumination is achieved. Excitation light remains constant when changing the objective, regardless of numerical aperture, and consequently always the same area is illuminated.

FLUOLED for reflected light fluorescence

Other than on transmitted light fluorescence, in reflected light fluorescence light comes from top and is concentrated on the sample through the microscope objective. FLUOLED® is available for reflected light fluorescence as a single one color filter wheel system and a multiple three color filter wheel system. The kit allows to transform the microscope into an epi-fluorescence units just by installing the illuminator between the microscope tube and stand. Light coming from the solid state sources (LEDs) is selected by dedicated filter blocks mounted on the filter wheel.

In REFLECTED LIGHT fluorescence power density of excitation light is increased by the numerical aperture of the objective. As a consequence the signal increases with the quality of the objective, i.e numerical aperture and magnification factor.