Mechanical micro-drilling tools currently can be used to drill holes up to a diameter of around 10 μm at a drilling depth of approximately 100 μm. The main issue with mechanical drills is the long processing time required per hole, the short service life of the drilling tool caused by wear and the aspect ratio.

In order to create small boreholes with a high aspect ratio, it is possible to use Bessel beams, which have the property of being almost diffraction-free over a relatively long beam propagation length. The central maximum of the Bessel beam is also narrowly limited, which enables small diameter drilling holes.

The aim of the project is to develop an optical module prototype that offers the possibility of creating a flexible arrangement of several Bessel beams for drilling a large number of microholes with a high aspect ratio, using a Spatial Light Modulator.

In order to be able to react to changing target patterns (number and arrangement of holes), the system should be able to change the drilling configuration. This is allowed by the use of a LCOS SLM, which can use digital holography for manipulating the shape of a light beam. An important technical aim is that the processing qualities of the drill holes must be independent of the number or position in the processing field. The optical system should be integrated into an existing laser processing machine based on a picosecond and femtosecond laser (depending on the material).

HOLOEYE tasks in the project

HOLOEYE develops an LCOS Spatial Light Modulator that is specially adapted to the high energy densities of ultrashort pulses. For this purpose, several LCOS versions are being developed with improved reflectivity/irradiation resistance (Laser Induced Damage Threshold, LIDT) for different wavelength ranges: 450 nm, 512 nm, 800 nm and 1030 nm.

The variety of versions / wavelength ranges enables the processing of different types of materials: semiconductors, ceramics, metals, polymers and circuit boards. A focus of the project is the investigation of the irradiation limit and the associated light damage threshold. The goal is to identify the damage caused by irradiation and develop strategies to increase the irradiation resistance of the LCOS SLM displays. Among these strategies are: the identification of highly stable Liquid Crystal (LC) materials, an effective thermal management of the microdisplay, and the development of highly reflective Dielectric Mirror Coatings for the CMOS backplane.

Funding Programm:
Project Coordinator:
Ruhr-Universität Bochum-Lehrstuhl für Laseranwendungstechnik (LAT)
Project Partner:
  • Ruhr-Universität Bochum-Lehrstuhl für Laseranwendungstechnik (LAT)
  • Technische Hochschule Aschaffenburg AG Angewandete Lasertechik und Photonik (AG alp)
  • GFH GmbH
  • HOLOEYE Photonics AG
Project Duration:
12/2019 to
Sponsored by