Many applications can benefit using a single laser machine which can switch between different wavelengths for different processes with high precision and without interruption of continuous work. Using standard refractive focussing lenses results in chromatic aberrations and in some cases spherical aberrations. For some time achromatic doublet or triplet lenses have been used to overcome these issues in multi-wavelength systems. Although aberration issues are largely resolved, other issues are introduced. The optics themselves are bulky, and due to the range of materials used and the bonded interfaces, can be susceptible to thermal focal shift and lower laser damage thresholds.
There are currently no effective refractive achromats available for the triple wavelengths 355 nm, 532 nm and 1064 nm. The diffractive achromat from Holo/OR offers diffraction limited performance due to the absence of aberrations, while maintaining high laser damage threshold and low thermal sensitivity.
Performance is optimised for all design wavelengths so that the operating wavelength may be switched and the system will continue to operate without focal length shift with no need for further adjustments.
Standard triple wavelength diffractive achromats offer a focal length of 150mm for the Nd:YAG harmonics 355 nm, 532 nm and 1064 nm, and are available on short lead times. Other focal length and wavelength values are possible upon request.
