Light
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[edit] Light Output Measurements
[edit] Lumens
Lumens is a measure of the total output from a light source.
[edit] MSCP (mean spherical candlepower)
MSCP is just another measurement of total light output. MSCP times 4 times pi = Lumens.
[edit] Candlepower
Candlepower measures the intensity of a light source at a single point a given distance from the source.
You cannot convert from candlepower to lumens. It's like the difference between pomegranates and watermelons - with one, you eat the seeds and throw away the flesh, and with the other, you eat the flesh and throw away the seeds.
There are a number of units for measuring intensity:
cd - candellas (Candlepower)
mcd - millicandellas
lux (essentially the metric equivalent of a candlepower)
Most flashlights will be measured in Lumens or Lux. The large spotlights are measured in cp. The strobe lights on fire alarms are always measured in candelas. ADA (Americans with Disabilities Act) requires a fire alarm strobe to be 15cd at 45degrees and 75cd on-axis.
[edit] Optics
Almost all flashlights have some sort of optics, being a reflector or collimator, or possibly a combination of the two if there is more than one light source. A few lights have recessed LEDs, that are surrounded by the flashlight body material, and feature no reflector(s) or collimator(s). But generally speaking, you will find at least one of the following two types of optics in flashlights.
[edit] Reflectors
- =Reflectors are the most commonly found type of optics for flashlights. They have a polished metal finish on them, and they reflect the light from the light source towards the target. Some are made smooth, and others are dimpled/stippled. The dimpled ones usually offer smoother beam patterns and come in higher quality lights, whereas the smooth ones have rougher looking beam patterns which aren't quite as nice. A few examples of reflectors are the IMS S017XA, S027XA, S020XA, and McFlood.
[edit] Collimators
- =Collimators are used only with LEDs, and they are clear plastic. They refract the light to adjust the beam. Both types of optics offer advantages and disadvantages, and people have different preferences. It also depends on the type of application. Examples of names of collimators are 30mm, Fraen, Fraen 30ยบ, Fraen-LP (low-profile), NX-01, and NX-05.
