I see that many LIDAR systems use power in the millijoule range in atmospheric research. A typical number is 25 millijoules. 25 millijoules is equal to 25 milliwatt/seconds. This means 25 milliwatts for one second. This seems like a tiny amount of power, yet a 25 millijoule laser costs many thousands of dollars. This does not make sense as you can buy a 25 milliwatt laser diode that will easily run for one second and it costs just a few dollars. What is the difference?