Diffractive laser monitoring provides realistic measurements

26th November 2014
Barney Scott


It is imperative, when monitoring laser beams, that the measurement beam is absolutely identical to the processing beam. In order to ensure a realistic reading, any measurements must be carried out during the laser process without affecting the beam.

One option is the use of a diffractive beam sampler to separate a small fraction of the main beam’s energy. The benefit is that the beams that are coupled out are a perfect copy of the original beam. Multiple beams allow power measurements and beam profile measurements to be carried out simultaneously.

In this process, the Diffractive Optical Element (DOE) is inserted into the path of the collimated beam.  Approximately 99% of the main beam is transmitted through the DOE without changing, and the remaining 1% of the beam intensity is split into higher orders for measurement purposes. The majority of this will go to the first order at a specified angle with subsequent orders receiving smaller fractions at wider angles.

The intensity of the sampled beams does not depend on the polarisation of the laser, meaning that the samples are completely identical to the main beam.

Laser Components UK offers a large selection of standard elements, in addition to custom or ‘semi-standard’ designs for the wavelength range of 193nm-10.6µm.

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