Fluorescence

Category: Pages
Published: Saturday, 16 March 2019 10:55

Ultraviolet Fluorescence

Ultraviolet light (UV) is invisible to the human eye but when certain substances are exposed to it, they emit visible light. I became interested in photographing fluorescence when a friend told me that scorpions appear blue under UV.  People rarely see scorpions because they are brown and well camouflaged but they are quite common where I live on the outskirts of Sydney and are easy to find at night by searching the leaf litter with a UV lamp.

My initial photos were disappointing because the backgrounds looked artificially coloured. I discovered that most ultraviolet sources, also emit visible light and cameras often show this visible light and reflected UV as unwanted colour. I built the lamp below to prevent false colours and I also use a "UV(0)" filter on the camera lens to prevent reflected UV light from reaching the camera sensor. My UV lamp and a selection of images exposed using UV and visible light are shown.

The lamp was built for less than AUD $100 and includes:

  • 10 watt 365nm UV LED
  • A black  "ZWB2" filter inserted beneath the LED and lens to block unwanted visible light emitted by the LED
  • Condenser lens on the front of the lamp to concentrate the UV into an intense beam which makes the fluorescence look more vibrant and reduces exposure time
  • Resistor and heatsink to prevent the LED overheating and to limit the maximum current
  • Rechargeable 3.6 volt lithium cell

 UV lamp

  

Diamonds - visible and UV light

 

Marbled Scorpion - UV exposure for 6 seconds at f16 and fill flash. Nikon D750, 180mm lens with UV0 filter, extension tube and tripod

 

Feathers - Fledgling Powerful owl feather and aSulphur-crested Cockatoo feather exposed with visible and UV  light

 

 

 Australian $5 note - visible and UV light

 

Eggs - visible and UV light

 

Lichen growing on sandstone - visible and UV light