For the first time, customers can now obtain notch filters that are exactly tuned for a wavelength of 10.6µm. This will allow the use of thermal imaging cameras for process monitoring of industrial CO2 lasers. The filters are designed to provide selective attenuation by a factor of 1000 along a 1.5µm wide band. At the same time, the entire thermal image is only darkened by approximately 25% over a transmission range of 3.5 - 14µm. Notch filters by Alluxa are now available at LASER COMPONENTS.
Notch filters “hide” specific wavelengths. To date, such filters have mainly been used for visible and near infrared wavelengths for applications such as Raman laser spectroscopy or confocal microscopy. There were only few options available for wavelengths in the medium and long infrared spectrum.
Thermal imaging cameras are increasingly used to monitor welding processes with CO2 lasers, and detect errors such as welding spatter or hairline cracks more quickly. These cameras are based on bolometer arrays that detect radiation in the range of 8-12µm which includes the CO2 laser wavelength. The intense laser light outshines the processes actually observed. To allow for efficient monitoring, these wavelengths have to be dimmed.
