Manufacturing and quality assurance of Gaussian mirrors

The significance of Gaussian mirrors, also known as Graded Reflectivity Mirrors (GRMs), lies in their ability to generate high beam intensity while maintaining superior beam quality. These mirrors feature a reflectivity that diminishes in a Gaussian pattern from the centre to the outer edges of the optic. Unlike traditional convex couplers with uniform reflection, GRMs with Gaussian reflection profiles enhance the central mode in the laser crystal by primarily reflecting the beam's central part. The outcome is a potent laser beam characterised by minimal divergence and outstanding far-field behaviour.

Gaussian mirrors are particularly beneficial in applications that require frequency doubling to produce specific wavelengths, such as in laser material processing within the medical sector or in LiDAR systems for atmospheric measurements.

In practical applications, GRMs are employed with monochromatic light. LASER COMPONENTS specialises in manufacturing Gaussian mirrors for a 1064nm wavelength, available in diameters ranging from 8mm to 25.4mm, with customisation options for different wavelengths and sizes.

One of the main challenges in producing these mirrors is maintaining a consistent reflection profile across various production batches. This requires stringent quality control, exceeding the standards set for conventional mirrors and lenses. An integral part of this process involves a detailed examination of each mirror's unique reflective profile.

To address this, LASER COMPONENTS’ development department has implemented an automated measurement station. Here, each Gaussian optic is thoroughly analysed using a continuous wave laser that scans across the mirror’s diameter, recording reflection values comprehensively. Only mirrors that meet every customer specification are approved for dispatch.

Customers can be assured of the consistency in every batch, with the added benefit of independently verifying this quality. Each Gaussian optic is accompanied by the actual measurement curve, offering tangible proof of its performance.

A satisfied customer who recently transitioned to LASER COMPONENTS’ Gaussian mirrors remarked: "We have very encouraging results – the [substrate] shape is not yet what we need, but the LiDT seems to be good."