Optimizing Laser Glass Cutting with Diffractive Beam Shaping
Laser glass cutting with ultra-short IR pulses is lately growing to become a key technique for the high throughput glass processing. Cutting thick glasses (>500um) using this technique possess unique challenges, as the laser energy needs to be both focused to a tight spot, and spread evenly in the glass depth.
Holo/Or offers several solutions to help our customers with their glass cutting needs:
For customers interested in a complete solution and optimal performance, we have recently launched the DeepCleave™ Module.
Other, component level Elongated Focus and Multifocal DOEs elements. These elements increase the focal depth of the beam, or split the focal region into several spots, enabling improved glass cutting performance. These components can be used with both single and multi-mode lasers with flexible input beam diameter and generally require external focusing optics.
Our DeepCleave module focuses an incident single mode laser into a tight spot with ~ 1.8 um waist size along the entire Depth of Focus range (1-2mm typical range) .
The focused spot is equivalent to 0.35 objective NA and is ideally suited for glass cutting of thick glasses, such as flat panels.
This module is a complete optical solution for cutting applications. No need for additional high NA objectives or other high cost optics.
The DeepCleave module differs from standard EF elements by constant peak power along the focus region and requires low M^2 and accurate input beam size.
Why choose DeepCleave for your glass cutting application:
- Full depth glass cut from single pulse.
- Complete solution in a single module.
- Very low aberrations level- spot diameter <2um.
- Easy to integrate into existing opto-mechanics.
Real Measurements of DeepCleave ZT Module 001-I done at ~X5 magnification using a moving camera + objective setup
Specifications of standard DeepCleave Modules:
Diffractive Multifocal Module
Diffractive Multifocal (MF) lenses are widely used for glass cutting applications. In this process, multiple foci are formed along the cutting path, thus increasing the speed and accuracy of the process.
To achieve optimal performances, small separation distances between neighbor foci and high-power densities are required. This is usually achieved with a high NA objective lens. However, the majority of off-the-shelf high-power objectives do not meet the application requirements and result in degraded performance.
To address this issue, HOLO/OR has develop a tailored focusing module for glass cutting applications, used with a Multifocal lens. HOLO/OR’s Multifocal module (MF module) maintains diffraction limited spots size at all foci.
Advantages of the MF module:
- Complete solution – no need to purchase the components from separate vendors.
- Enhanced performance – very low aberrations level, Diffraction limited spot size.
- Accepts large input beam diameter (15mm or more), enabling smaller spots.
- Tailored per customer’s parameters.
- Compact module.
- Achieves more accurate results and increases process throughput.
The benefit of the extended focus, vs. Multifocal products, is that it produces a continuous intensity profile along the DOF, and doesn’t suffer from areas with low energy between neighboring focal spots.
A diffractive Elongated Focus (EF) element generates a Bessel beam that extends the depth of focus far beyond the Rayleigh length, while maintaining diffraction limited spot size. We offer a wide selection of EF elements with various ranges of focal depths, as well as custom focal depths tailored to your system’s requirements. Click here for more information.
A diffractive Multifocal (MF) allows you to focus your laser beam simultaneously at several focal points along the propagation axis. This element is suitable for single-mode and multi-mode laser systems and produces an output beam that is focused at a number of focal lengths, which are determined during the design according to your requirements. Click here for more information.