Optical Absorption Coefficient, Time of Thermal Relaxation, Time of Surface Threshold, and Time of Heat Incubation for PMMA Samples at the CO₂Laser-Beam Wavelength of 10.6 µm

Abstract

The value of alpha = 502 (cm(1)) for PMMAat 10.6 microm was identified, matching other results reported in the literature for similar compact media in the absence of water content, such as PMMA. The time of thermal relaxation was 9.358 x 10(4) sec, the time of surface threshold was 9.365 x 10(4) sec, and the time of heat incubation was 3.6 x 10(7) sec (all three for PMMAat 10.6 microm for any exposure). Using the calculated value of alpha, one of the practical clinical recommendations would be, for instance, to reduce or to abolish the utilization of colorant dopants in the preparation of the bone cement mixture and therefore reduce the danger of bone damage possible during the removal of bone cement via laser techniques. Other examples refer to other clinical bone and dental treatments.

CO2-laser micromachining of PMMA: the effect of polymer molecular weight

“…In the laser cutting process of a plate of homogeneous and isotropic material absorbing a monochromatic and parallel laser beam of incident power density I 0 , which gives the power density I at depth z, the value of I can be given as I = I 0 e µz where µ is the linear absorption coefficient (cm −1 ) [20] and its value for PMMA ranges from 10 2 to 10 5 cm −1 [19]. The absorption coefficient is independent of the polymer molecular weight [30] and for PMMA, it is 502 cm −1 at the wavelength of 10.6 µm [33]. Figure 1 shows a Gaussian-like profile cross-section of 96.7 kDa PMMA at a laser power and speed of 1 W and 7.04 mm s −1 , respectively.…”

Temperature‐controlled two‐wavelength laser soldering of tissues

“…The thermal constants (specific heat capacity: c % 1,500 J kg À1 8C À1 [20]; thermal conductivity: K % 0.197 W m À1 8C À1 [20]; and convective heat transfer coefficient: h % 8 W m À2 8C À1 [21]) of Lucite are of the same order of magnitude of most tissues. Lucite also highly absorbs CO 2 laser radiation (m % 50,200 m À1 [22]) and barely absorbs the diode laser radiation (m % 0 m À1 , measured using an FTIR). Therefore, the two-wavelength system could be used to heat the upper and lower surfaces of such a phantom.…”

Theoretical and experimental investigations for geometrical error during hemispherical cavity machining on CO2 laser

“…CO 2 laser cutting of PMMA with controlled parameters results in clean medical structures with minimal heat-affected zones. 10 Chen et al showed that CO 2 lasers are a simple and convenient processing method for micro-channel fabrication of various shapes on PMMA material by controlling the laser powers. 11 Kurt et al utilize ANOVA and regression methods to study the influence of process parameters on kerf-width and showed that workpiece thickness also affects the dimensional accuracy apart from other parameters.…”