Buying a laser power meter: check-list

Because of the wide range of power and energy meter available on the market, and even more because they tend to be not totally versatile, you need to carefully examine your needs against the capabilities of the instrument you are planning to acquire. Here is a little check list to help you decide if a laser power meter or energy meter would fit your application.

  • Is the meter’s calibration traceable to internationally recognized standards such as NIST?
  • Is your laser wavelength within the wavelength range of the power meter?
  • What is the power range you expect to measure (highest and lowest limit)? Does it fall within the range the power meter can measure?
  • What is the diameter of your beam at measurement point? Do you have any control on this (using a lens for instance)? Is the power meter aperture big enough?
  • What is your power density (W/cm2) and energy density (J/cm2)? Is it below thedamage threshold of the power meter?
  • Is your laser a pulsed femtosecond? If yes you will need a flat spectral response across the laser bandwidth. This may also be the case if your laser is widely tunable and you can’t adjust the wavelength setting manually, or simply if you don’t know your wavelength.
  • Is your laser pulsed and do you need to measure each pulse’s energy or an average power is sufficient? If the average power is enough or if you want to measure a single pulse energy, a thermopile is better. Otherwise you will have to go for a pyroelectric sensor or a specialised photodiode
  • Are there a lot of vibrations in your environment? If so this would rule out a pyroelectric detector.
  • Most power meters are sold nowadays in a set of two separate items: a display and a sensor. Make sure you order both and that they are compatible with each other
  • Assess what type of display you need: do you need computer connectivity, LabView compatibility, is it to go “in the field”, do you need it wireless (yes some manufacturer do that now)…

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