I have some laser diodes. I want to know how to measure the wavelength of laser diodes ranging from visible to near infrared? (300 nm to 1100 nm)

What type of instrument/meter do I need to use? spectrometer, spectrophotometer, wavelength meter, reflectometer, oscilloscope or what and how?

  • 2
    $\begingroup$ This question recently came up on physics.SE, and Floris's answer to the question is quite excellent. How to measure the wavelength of a laser pointer? $\endgroup$ Jul 6, 2015 at 11:51
  • $\begingroup$ What sort of resolution do you need? (a few nm?) I'm think a wave-meter will be over kill for you. (and too expensive) A spectrometer would be fine. Or as Chris M. links to above get a diffraction grating, measure the angle and do the math. $\endgroup$ Jul 9, 2015 at 18:28

1 Answer 1


You want a wavelength meter if you have one or otherwise a spectrometer. In more detail:

  • A wavelength meter uses an interferometer to measure wavelength. It can measure wavelengths very accurately.

  • A spectrometer measures a spectrum, that is intensity vs wavelength. The wavelength at the peak intensity is what you are looking for.

  • A spectrophotometer is used to measure the transmission spectrum of some material. This is not what you want.

  • A reflectometer measures reflectivity. Again, not what you want.

  • Oscilloscopes measure electrical voltage vs time. Again, not what you want.

  • $\begingroup$ Thanks for help.Do you know any basic entry level Wavelength meter model # ?. $\endgroup$ Jul 7, 2015 at 15:06
  • $\begingroup$ Good sources for optical equipment like this are newport.com and thorlabs.com. If there is an inexpensive version, then edmundoptics.com will likely sell it. $\endgroup$
    – John1024
    Jul 7, 2015 at 18:01

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