Iluminated Stand Magnifiers
Why is illumination important and valuable in stand magnifiers?
Illumination enhances contrast, where contrast is the ability to visually separate an object from its background. Black print on a white page is the classic example.
If we illuminate an object and enhance the contrast of the image, we may then also need less magnification for the visually impaired user to be able to satisfactorily see the object.
With illuminated stand magnifiers, there are three different and unique light sources available: incandescent, halogen (or xenon) and LED, or Light Emitting Diode.
Incandescent lights offer a medium intensity light source with a more yellow spectrum. They are designed around a simple wire filament that, when current is passed through it, glows and emits light.
Halogen lights offer a high intensity light source also with a yellow spectrum. They are similar in design to an incandescent bulb, but have a larger bulb housing and a stronger filament. These features allow halogen bulbs to carry more current and, therefore glow at higher temperatures than incandescent bulbs.
LEDs are a newer type of light source. They are microchip-based light sources that use light to dissipate excess energy in a circuit. Originating in wristwatches, LEDs have become more versatile and energy efficient since their introduction in the 1970s. LEDs, as used in low vision devices, exhibit a much whiter and brighter light source that provides better black on white contrast enhancement, but may cause discomfort due to glare.