Skin Scanners: Not Created Equal

by Ralph Hill - Internet Technology Researcher and Writerby Ralph Hill - Internet Technology Researcher and Writer

There is no doubt that skin scanner or “Woods Lamp” UV skin diagnostic devices are a valuable asset in the skin treatment professionals skin assessment toolkit. There are many brands to choose from and prices can vary by as much as 30-40%.
The question is of course, do the lower priced units work any better than devices with a higher price tag?

The basics

Most skin scanner devices feature the same basic fundamental design, and this is a housing containing a UVA (Black light) light source with a viewing port on one side and a large aperture for a person to position their head. There is an adjustable curtain on the larger opening that helps control ambient light bleed.
Physical design differences are usually limited to the aesthetic appearance of the housing, with the molded of sheet metal, and while perhaps not looking as pleasant as the rounded housing, are strong and functional.
Some devices feature fans to circulate air and increase the patients comfort while in use, and this will generally incur a cost premium.

The construction and comfort features aside, there is one single parameter that either makes the skin scanner a valuable tool or a frustrating ordeal for the user. This is the quality of the UV light source. Most devices use fluorescent “black light” tubes as their light source, and it is the type and quality of these tubes that make or break the functionality of the device.
There are essentially two types of black light tubes available and unfortunately it appears some manufactures of skin scanners don’t seem to know the difference. They are:


These tubes emit UV rays of highest intesity of around 360nm and attract insects into insect traps, are used in mineralogy, military, criminology, medical and pharmacy industries, to monitor photochemical reactions, examine jewellery and the verification historical relics etc. The spectral output of these tubes however, is relatively wide, with secondary peaks around the 520 and 540nm regions.




Blacklight Blue:

These tubes are made with Wood’s glass and also emit UV rays of 360nm at high intesity and are commonly used to detect counterfeit currency, special stage effects, dermatology and other applications similar to blacklight Lamps.
The difference is that spectral ourput of these tubes is much more “focussed” around the 360Nm region, with virtually no unwanted seconday spikes.

As you can see by the two spectral charts, plain Blacklight has energy spikes in other parts of the spectrum that really spoils the ability to accurately display the skin emitting light energy of specific frequencies when exposed to UV radiation.

The different colours emitted (and viewed by the therapist) correspond to a variety of biological ecosystems, and consequently skin conditions. 
Because the wide band UV from the Blacklight tubes has frequencies we don't want, the detail that shows what is occuring in and on the skin is "washed out" with the additional unwanted light. Everything looks "too blue", without the subtle colour differeintation.

The images to left are examples of the extremes of tube quality.
You will note the cheaper tubes are almost useless as a diagnostic device due to the "bleed" of unwanted blue light from the upper spectrum.


The higher quality tube provides more difinition with a subtle "sharpness".
With the higher quality tube, the oil flow on the upper cheek is visible, as there is the correct part of the UV spectrum at the right intensity.
The correct bandwidth of light also shows the underlying pigmentation that is washed out by the cheaper tubes. 


Tube quality:

High grade tubes are made from special blue glass that filters out most of the visible light, letting only the UVA ultra violet light pass through. Cheaper, less efficient (spectral bandwidth and energy output) tubes are internally coated with a dye that makes the tube glow blue.
The latter has a much wider spectral output, but little usable energy in the important 360nm range, providing generally poor results as a diagnostic tool.
These types of tubes are mainly used for display and theatrical purposes. Unfortunately, some lower cost skin scanners come from the factory with these tubes fitted. The good news is that they are easily replaced with better quality tubes. An example of what to look for on the labels of the tubes is below.


The black light skin scanner can be a useful diagnostic tool if fitted with quality Black light blue tubes. The higher the quality the tube, the "tighter" the bandwidth of the light source.

More recent technologies that use precision narrow-band LED's as their light source are quickly making the fluorescent black light tube skin scanners obsolete however.  Check out this amazing technology here....


About the Author

Ralph Hill is technology writer, illustrator and editor for Virtual Beauty Corp. He has a background in science, electronics and electro-mechanical devices, but enjoys researching and writing for a myriad of skin care related topics including cosmetic chemistry and anatomy & physiology.




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