flo: Additive manufactured coatings

The eyewear industry has long relied on conventional methods for lens production and coating. In terms of coatings, the start-up flō Optics now wants to revolutionize this market. The first market-ready machine will soon be presented. Find out what’s behind the technology.

The company plans to pioneer lens coating technology and transform ophthalmic labs by merging precision, sustainability, and creative freedom. With its digital coating system, the company plans to deliver customization and efficiency while at the same time addressing current industry challenges such as inventory cost, production inefficiencies, and environmental impact.

As traditional lens coating processes are well proven for mass production but at the same time, are often based on rigid and resource-intensive techniques that limit design flexibility.

From flō Optics’ perspective, the advent of direct digital coating technologies represents a quantum leap in optical manufacturing, offering many capabilities in lens surface modification. Furthermore, the procedure is easy: opticians capture desired colors or patterns using the provided software and send it to the Rx lab with their order. The digital files are then transmitted to the printer, and finally, the coatings are applied directly and accurate onto the lenses.

Digital printing process

flō Optics’ additive manufacturing technology for spectacle lens coatings is a modular multistage production line in which functional optical inks are digitally printed directly onto the surface of any type of Rx and non-Rx lenses.
In this modular coating system, lenses are transferred between various stations for surface treatment, digital printing, drying and inspection.

The patent-pending process produces photochromic, tinting, and hard coat functional coatings, which are characterized by an engineered multilayer/multi-material optical stack structure.

Structured multilayer/multi-material coatings are produced by a series of non-contact ink deposition print heads, controlling the process at the level of a single drop. The level of material deposition control enabled by the coating process enhances the performance, repeatability, and quality of the functional coatings.

Photochromic coatings produced by the company’s proprietary multilayer/multi-material approach are a prominent example of how engineered layers have a direct impact on performance. In this case, the layer’s chemical and mechanical properties create an optimal environment for the photochromic dyes, potentially allowing a faster fading time than existing spin photochromic coatings.

Countless possibilities

The digital platform supports a wide spectrum of coating designs, from subtle seasonal tints and gradients to complex, customer-specific patterns, all achievable without carrying semi-finished inventory.

Photochromic coatings also achieve good performance in a variety of colors and gradients and all imaginable patterns are possible. For general tinting, all colors requested by the customer are possible, and the tinting ink can be discretely deposited on any pre-determined area of the lens (Fig.1), with digital printing accuracy and repeatability. Also, hard coatings can be applied with enhanced durability and without batch processing. Whether on traditional lens materials or on challenging substrates like polycarbonate, the system delivers consistent, high-quality finishes.

Coating application mechanism

The high quality is achieved by several steps. Firstly, by a digital printing interface that converts digital design specifications into precise coating instructions.

Next, a controlled droplet deposition ensures uniform coating distribution with minimal material wastage, and finally, the real-time calibration continuously monitors and adjusts coating parameters, with an inline inspection module using image processing and spectrometry.

Every produced lens is analyzed, and data is provided on product and process quality. The digital coating system introduces several critical technological advances:

Precision micropatterning: Enables coating application with micron-level accuracy, transcending traditional dip-coating or spray techniques.

Material substrate versatility: Capable of applying specialized coatings across diverse lens materials, including challenging substrates like polycarbonate and high-index polymers.

Material science and coating dynamics: The digital coating technology leverages advanced material science principles like inkjet materials formulation that ensure optimal coating performances across diverse lens substrates.

The micron-level-accuracy application enables the creation of ultra-thin, uniform protective layers. The customizable surface modification allows introduction of specific optical, protective, or aesthetic properties.
Additionally, the system supports the introduction of new types of materials that traditional processes are not able to handle, or that are too expensive if applied on all the lens surfaces. And finally, the digital workflow integration is a seamless software-driven process that transforms coating from a purely mechanical operation to a data-driven, programmable manufacturing step.

Why digital coating?

The demand for personalized, sustainable, and cost-effective eyewear is growing. The start-up provides a solution that addresses those needs while enhancing lab profitability and customer satisfaction. Traditional coating methods require maintaining large inventories of pre-coated lenses, many of which risk obsolescence. This system should enable labs to coat lenses on demand, reducing overhead costs and waste. Some examples of the economic advantages are: elimination of semi-finished inventory holding working capital costs, reduced material consumption, and greater production flexibility, which accommodates seasonal trends or custom orders.

Sustainability redefined

The digital coating process significantly reduces water and energy consumption while minimizing waste, aligning with the growing demand for green manufacturing. The company estimates a reduction in water consumption of around 80%.The chemical waste is reduced compared to a traditional process and the process leads to minimized transportation-related carbon emissions due to on-demand production.

From flō Optics´ perspective, the digital coating technology marks a critical inflection point in optical manufacturing. It transforms lens production from a standardized industrial process to a flexible, data-driven, and environmentally conscious technological ecosystem.

Dr. Claudio Rottman Savion is the CTO and founder of flō Optics Ltd. He has more than 25 years of experience in leading multidisciplinary research in the field of digital and additive manufacturing.

He was Chief Chemist for printed electronics in the FPD division of Orbotech and the Chemistry Manager in the 3D printing Company Objet (today Stratasys). In his last position before founding flō Optics, Claudio was part of the core team of HighCon Ltd., serving as Materials and Technology R&D Manager. Claudio holds a PhD in Chemistry from the Hebrew University of Jerusalem, Israel. He is the author of more than 70 patents and scientific publications related to the different areas of his professional career.