The principal of OEM harmonic generators operation is based on collinear generation of higher laser radiation harmonics in angle phasematched nonlinear crystals. The optical layout of OEM harmonic generator also includes beam reduction and collimation optics that ensures the highest harmonics conversion efficiencies. In a standard setup particular harmonic is produced in a single OEM harmonic generator module, different module is required for different order harmonics generation.
Automatic harmonic modules are also available allowing selection of fundamental, second, third or fourth harmonic output by a control software. All the accessible harmonics exiting OEM harmonic generators are separated from the pump radiation by dichroic mirrors.