Here are some of the things used to rate and promote laser modules and laser pointers:

• Wavelength: Human eye perceives colors differently. Usually, wave closer to 540nm is better since visibility is a strong function of wavelength. However, the variability can be significant - a laser pointer at 640 nm might have almost a 2:1 ratio of relative brightness, compare to a 650 nm laser. Or 450 nm blue laser is brighter than 405 nm. The infrared laser modules use the wavelength more than 780nm and cannot be visible.

• Output power: Power ratings are often made deliberately confusing like "<5 mW", which could mean 1m~5mW! Even among identical models, there can be significant variation, especially for green DPSS laser modules. Please clarify the output power clearly cause eGismos is especially concerned about safety and brightness.

• Visibility: Manufacturers will often compare visibility to the 670 nm wavelength. All but the cheapest pointers today will be somewhere in the 635~660 nm range. Between the available wavelength of 635 nm and 670 nm is a ratio of relative brightness of about 7:1. If need the laser for invisible application, the wavelength would have to be more than 780nm (infrared laser).

• Distance/range: Laser light doesn't travel a specific distance and stop, or suddenly become too dim to be seen. It's only possible value would be in comparing various models, they probably just associate a particular value with the output power, wavelength, or the the laser spot size of the operating distance.

• Beam shape/quality/spot size: Without proper optics, the output of a red diode laser pointer won’t be nice round (dot). More expensive pointers may have the necessary optics to do a decent job of beam shaping but most do not. For pointing at normal viewing distances, what clients care the most is usually - spot size at a certain distance.

• CW or pulse modulation: Most laser modules or laser pointers produce a continuous (CW) beam. However, due to the way green DPSS lasers work, pulsed systems have significant advantages in terms of efficiency and thus battery life. The laser modules could also benefit from pulse modulation for some special applications, but it would require a higher power output, more expensive laser diode, and more complex driver.

• APC or ACC driver: Most laser modules, laser pointers use Automatic Power Control (APC) to maintain the output power constant over temperature and until the batteries are nearly dead. The laser diode package itself has a built-in photodiode behind the laser diode chip for this purpose. There are only very cheap laser pointers that forgo this feature and simply use a current limiting resistor.

  Most green laser pointers in the past used Automatic Current Control (ACC) - a constant current driver. The result is generally fluctuations in output power as the pointer heats up. These may be quite large and result in either a very dim spot or an excessive and illegal super bright beam. The trend now is to use an APC driver to eliminate variability and also make it harder to "boost" the output to an illegal and dangerous power level.

• Plastic versus glass optics: Plastic is softer than glass so if the surface of the collimating lens is exposed, it will be more easily damaged through carelessness and cleaning. And the advantage of glass lens has better reliability for environment and temperature variation.

• Multiple pattern generating optics:These are the sort of thing that appear as a line, cross line, ground line, HOE or patterns (DOE).

• Life expectancy and warranty: Sometimes there will be a spec like "2,000 hour lifetime". This is probably mostly relevant for the laser modules or laser pointers and may be reasonable.