Previous work with fibre lasers has established that certain black grades of acrylic are highly absorptive of 1 micron wavelength. However, transparent PMMA cannot be used in fibre laser cutting as it does not absorb the fibre laser wavelength of 1.06µm. Beam prints in poly-methyl methacrylate (PMMA) has previously been shown to be useful as a cheap analytical tool for CO2 cutting. Beam prints can be useful in terms of quantifying how much light is lost from the process, as well as indicating the nature of the reflections taking place in the cut zone.
This can be done by investigating how much laser light passes through the cut without being absorbed. There is an associated interest in ensuring the process is efficient. The theory is applicable to both the linear polyatomic molecules and the diatomic molecules.Fibre laser cutting technology has become interestingly prevalent. Theoretical interpretation given earlier for laser action on vibrational-rotational transitions is discussed in a generalized form. A study has been made of the time dependence of the laser output under pulsed excitation, and some conclusions about possible excitation processes are given. These are ascribed to possible pressure-dependent frequency shift effects. The wavelength measurements are in reasonable agreement with earlier measurement of the bands in absorption, but there are slight differences. No R-branch transitions have been seen to oscillate either under cw or pulsed discharge conditions. All these laser transitions can also be made to oscillate under pulsed discharge conditions with a small increase in the peak laser power output. A cw power output of about 1 mW has been measured. Strongest laser transition occurs at 10.6324μ (vacuum). The laser wavelengths are identified as the P-branch rotational transitions from P ( 12 ) to P ( 38 ) for the 00☁-10☀ band and from P ( 22 ) to P ( 34 ) for the 00☁-02☀ band. We have obtained cw laser action on a number of rotational transitions of the Σ u + − Σ g + vibrational band of C O 2 around 10.4 and 9.4μ.
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