Most lasers are electrically inefficient devices.?

Question

a) True

b) False

Answer 1

I would say false, but jees, that it a really crappy question if it was in a test. what is the definition of inefficient, 50% 80%?

Answer 2

a) true

Lasers are horribly inefficient.  For example, an argon-ion laser generating around 5 watts of light total will take 30 amps of current at 208 V to generate that current.  So the laser is using 6240 watts of power to generate 5 watts of light, the rest of that power going down the drain in the cooling water (or into the air if it's an air-cooled laser (although nobody in their right mind would try to air-cool an ion laser that big).  In other words, it's net efficiency is a little less that 0.1%.  Solid-state lasers like Nd:YAGs are better in terms of overall efficiency, but not much.  

Lasers are a great way to turn current into heat, generating a small amount of light as a by-product.