Assessment of LED illumination cone

There is much potential for the use of light-emitting diodes in a light-weight orbiting microscope. Here the available LED's are assessed for light contour and intensity. A customised grid was designed, so that the light path could be objectively measured. Of the LED's currently available, one emitting apple-green light proved to be the brightest and has the best focussed beam. This is the wavelength currently used for the calibration of achromatic lens systems (used in microscopes). Since the sensor is not colour sensitive, this fortunate coincidence gives the best source of illumination for a modern microscope.

Amber LED Blue LED Green LED
Blue LED Yellow LED Fibre Optics compared

Customised grid nominal calibration:
Vertical Line separation = 1mm
Horizontal Column separation = 5mm

A selection of light-emitting diodes are here compared for light intensity and shape of cone. As a consequence of these readings, the green LED has been selected for further investigation.

Go to next phase.