| 摘要 |
<p>The invention concerns a method of marking PET material by illuminating the PET material that has previously been mechanically stressed with CO2 laser light in the range of 9.2 to 9.4 micron wavelength. Preferably, the laser light has a wavelength of 9.3 microns, but it may comprise a number of wavelengths within the range. It has been found that marking PET material by such a method provides unexpectedly improved marks which provide enhanced reflection surfaces and thus 'brighter' marks when illuminated with visible light than marks formed by marking at other wavelengths.</p> |
