Tecnica’s LFOS technology redefines precision in SLS/SLM 3D printing – Interview with Charles Bibas

Tecnica specialises in Selective Laser Sintering and Selective Laser Melting technologies, designing and manufacturing industrial-grade 3D printers and print heads for the production of plastic and metal parts. Founded in early 2014 by Charles Bibas and Diana Rozenblum, the New York based company has developed the innovative approach of High-Definition (HD) SLS and SLM. In an interview with 3Druck.com, founder Charles Bibas shares his expertise on the patented technology.

Recognising the significant costs associated with software patches and hardware fixes that only reduce rather than eliminate galvanometer-induced inaccuracies, Tecnica has developed a unique approach: High Definition (HD) SLS/SLM. At its core lies the patented Lens Free Optical Scanner (LFOS) technology. 

Unlike conventional methods, LFOS employs only mirrors to precisely focus and direct the laser beam across the build platform. This innovative approach ensures the laser beam remains consistently in focus and perpendicular to the surface, eliminating the distortion and quality issues prevalent in galvanometer-based systems. 

In contrast, traditional galvanometers produce a beam that varies in size and shape due to its focal point being on a spherical surface while the print bed is flat, compromising part accuracy and material integrity. To address these challenges, manufacturers often rely on expensive f-theta lenses and complex positioning systems.

Printers and Printheads by Tecnica

Tecnica offers the Casa II and Casa II Pro systems as entry-point solutions for polymer-based 3D printing, with a build volume of 120 x 95 x 150 mm. For Original Equipment Manufacturers (OEMs), Tecnica provides light engines (printheads) in two configurations: A95 and A150, featuring scan widths of 95 mm and 150 mm, respectively. These light engines can be integrated into systems with build volumes of 95 x Y x Z or 150 x Y x Z, where Y and Z dimensions are determined by the system integrator.

A key advantage of Tecnica’s LFOS technology is its inherent scalability. Unlike galvanometer-based systems where accuracy is influenced by printer geometry, the LFOS’s optical precision remains consistent regardless of system size. For instance, an integrator can construct a 150 x 500 x 500 mm 3D printer using Tecnica’s light engine, with overall system accuracy primarily determined by the quality of the actuators rather than optical limitations.

The company is currently developing  the A400 light engine, which will be integrated into the Optima metal printer, scheduled for release in Q4 2025.

Interview with Charles Bibas

In an interview with 3Druck.com, founder Charles Bibas explains the advantages of Tecnica’s HD SLS/SLM technology over standard galvanometer-based 3D printers and shares his extensive knowledge in the field. He also shares his general thoughts on other important technological advances in AM and possible future developments within the sector.

What are the problems that arise with standard galvanometer-based 3D printers that can be solved with Tecnica’s HD SLS/SLM technology?

GENERAL LIMITATION AND IMPACT

Issues with galvanometer scanning capabilities are not new. While the semiconductor industry has addressed these challenges for work surfaces of around 50 mm in diameter in the medical world for scan areas limited to 3 x 3 mm to achieve 9 micrometers in resolution for retinal scanning, these solutions are not ideal for SLS/SLM applications when scaled up.

Conventional SLS/SLM printers rely on galvanometers and lenses to deflect the laser beam rapidly across the print bed. This approach offers functionality but has limitations, especially for larger or high-precision prints:

• Speed – Galvanometer movement introduces a physical barrier to achieving high printing speeds.
• Accuracy – Precise beam control becomes more difficult with larger scan fields, leading to consistency in part quality.
• Bonding Energy – Inconsistent energy deposition across voxels leads to variations in bonding strength between neighbouring voxels.
• Complexity – Multi-laser systems, required for larger build volumes, introduce additional maintenance and calibration challenges.

CHALLENGES FOR INTERLAYER BONDING

3D printing using SLS/SLM involves sintering neighbouring voxels (3D volumetric pixels) to form a part layer-by-layer. The limitations of galvanometer-based scanning are amplified for interlayer bonding, making it more challenging to create strong and consistent bonds between layers.

The angle of incident (the angle between the laser beam and the normal to the surface) plays a critical role in achieving optimal bonding. Any deviation from a perpendicular angle (an incident beam of 0°) negatively impacts both accuracy and microstructure integrity.  Even if a closed loop system is deployed and positions the laser beam at the exact location on the top layer, the interlayer bonding will be shifted because of the non-0° incident beam as Figure 2 illustrates.

In addition to the previously mentioned factors, several practical challenges arise when working with galvanometer-based systems:

• Linearity Error: The galvanometer mirror is driven by a motor controller that commands specific positions. However, there is often a discrepancy between the commanded and actual positions, known as linearity error. This error, measured in radians, is typically provided by the galvanometer manufacturer.
• Offset/Drift Error: Offset/drift errors occur when the galvanometer deviates from its origin, affecting the positioning of all subsequent coordinates. These errors, also measured in radians, are influenced by temperature and require close monitoring. Real-time corrections can mitigate the impact of offset/drift errors.
• Repeatability Error: Repeatability error refers to the inconsistency in returning to a specific position. This error, measured in radians, is another factor affecting accuracy.

These angular errors are converted into linear deviations based on the 3D printer’s geometry, specifically the distance between the galvanometer and the print surface.

By comprehensively understanding these challenges, Tecnica has developed advanced SLS/SLM technologies that effectively address these limitations, resulting in superior accuracy, and consistency.

TECNICA’S HD SLS/SLM WITH LFOS

Tecnica’s HD SLS/SLM technology overcomes these limitations with the innovative LFOS system. Here’s how:

Designing an optical scanner where the laser beam focus is on a flat surface by definition and therefore, no correction or lenses are needed, resulting in:

• Unmatched Speed: LFOS eliminates the need for galvanometers, enabling significantly faster scanning speeds and drastically reducing printing times.
• Superior Accuracy: The direct laser beam manipulation by LFOS ensures exceptional precision across the entire print bed, resulting in high-definition parts.
• Simplified Design: A single, scalable laser eliminates the complexities associated with multi-laser setups, leading to improved reliability and reduced maintenance needs.

TECNICA’S NEXT STEPS

LFOS technology presents significant opportunities for enhancing quality assurance (QA) and quality control (QC) in additive manufacturing:

• In-situ Write-Read Capability: Leveraging the constant optical path length (OPL), LFOS can simultaneously write and read voxel data using a beam splitter and Optical Coherence Tomography (OCT). This enables real-time imaging and analysis of the current layer and up to 2 mm of underlying layers (depending on material). By detecting anomalies during the printing process, the system can initiate corrective actions or halt the process to prevent defects.
• Real-time Temperature Monitoring: LFOS can also provide real-time temperature measurements of individual voxels. By utilising a beam splitter to capture reflected energy from the surface, the system can accurately determine the temperature distribution within the build volume. This information is invaluable for optimising process parameters and ensuring consistent part quality.

Additive manufacturing has developed continuously over the last few years. Which other innovations or technological breakthroughs do you consider to be particularly important for the industry?

While Tecnica’s HD SLS/SLM is a significant advancement, the AM industry is constantly evolving. Here are some other key innovations to watch:

Multi-material printing: Combining different materials within a single build opens doors for complex functional parts.

Hybrid AM processes: Integrating AM with traditional manufacturing techniques allows for greater design freedom and part functionality.

Sustainable materials: The development of eco-friendly materials will minimise the environmental impact of AM.

First Corona and now high inflation are major challenges for the whole industry. How do you think the multiple crises affect the additive manufacturing industry?

The COVID-19 pandemic and inflation pose challenges for the AM industry. However, AM’s inherent advantages such as on-demand production and customisation might prove beneficial in mitigating supply chain disruptions.

What impact do you think additive manufacturing will have on different industries and possibly society as a whole in the coming years?

AM is poised to significantly impact various industries. From personalised medicine and lightweight aerospace components to rapid prototyping and on-demand manufacturing, AM promises to revolutionise how we design, develop, and produce objects.

This promise will be materialised not before a machine-centric standard is fully utilised (knowing ahead of time what tolerances a machine can deliver). A machine-centric standard will increase consumer confidence in the 3D industry.

Additive Manufacturing (AM) is poised to revolutionise industries from personalised medicine and lightweight aerospace to rapid prototyping and on-demand production. Realising this transformative potential hinges on the widespread adoption of machine-centric standards, which establish precise tolerances and capabilities for different AM systems. By providing clear performance benchmarks, these standards will significantly boost consumer confidence in the 3D printing industry. Tecnica has pioneered the development of a machine-centric standard capable of quantifying the performance of any galvanometer-based system.

Here you can find further information on Tecnica.