In the first article (Issue 3, 2026), Jonas Heelein looked at droptical’s beginnings. He also explained how the development of a jet dispenser eventually led to a company fully focused on dropwatching. In this second article, Heelein takes a deeper look at the technology. He looks at what makes droptical different from conventional dropwatching systems. Additionally, why this approach requires the development of an entirely new camera.
“droptical is setting a new benchmark for dropwatching”
A dropwatcher is more than a camera. Optics, illumination, electronics and software must work together as one measurement system. Therefore, droptical started with the measurement itself rather than building around existing industrial components.
This approach led to the company’s camera platform and system architecture, designed specifically for dropwatching. The system provides precise synchronisation and optics to integrated processing and open interfaces.
The architecture follows a simple principle – everything required for image acquisition belongs in the compact Camera Unit. While processing, software and interfaces are handled by the separate Control Unit.
The jetting controller system or the primary control system (such as PLC) determines when a measurement should take place. From there, the camera takes over. It synchronises the image sensor and strobe illumination before transferring the image data to the Control Unit.
At the heart of the Camera Unit is a custom-developed mainboard. It incorporates a 2.2-megapixel image sensor, a microprocessor for precise timing and a direct connection for the strobe light.
The microprocessor co-ordinates trigger, sensor and strobe which precisely align the light pulse with the exposure of the sensor pixels. This enables very short exposure times from 30ns. It supports high image rates while reducing the influence of ambient light to a negligible level. The result is highly reproducible imaging conditions for subsequent analysis.
The precise synchronisation also makes it possible to capture the very first droplet of a jetting sequence. This is particularly relevant in inkjet applications, where the first droplet can behave differently from those that follow.
Another – often overlooked – factor is pixel size. When comparing dropwatchers, optical magnification is frequently considered first. However, 5X does not necessarily provide better resolution than 4X. The resulting pixel resolution – or, more precisely, the object-space sampling – depends on both sensor pixel size and magnification. Pixel resolution in object space = sensor pixel size/magnification.
A typical sensor with 3.75µm pixel size and 5X magnification results in 0.75µm/px resolution. The same setup with the droptical camera results in a resolution of 0.56µm/px.
The comparison shows that using the same lens results in significantly higher resolution. In addition – even at a lower magnification – it results in a slightly better resolution. This provides flexibility in lens selection as well as in balancing high resolution, form factor and cost.
However, pixel resolution is not the same as optical resolution. Every lens has a physical resolution limit. Once that limit is reached, additional pixels or higher magnification do not create additional image information. Therefore, the complete combination of sensor, pixel size, magnification and optical performance determines the actual result.
The Control Unit combines software, image processing, database and interfaces in a self-contained system. This eliminates the need for an additional computer or dedicated software. The system is plug-and-play and is operated through a standard web browser. Integrated laboratory software provides many droplet analysis features, stitching, presets and measurement storage.
For machine integration, input/outputs (I/Os) allow direct interaction with equipment and PLCs. Meanwhile, the representational state transfer application programming interface (REST API) provides full remote control of the dropwatcher. This enables individual workflows combining equipment from different manufacturers. For example, positioning an axis, changing printhead or jetting parameters, triggering a measurement, analysing the droplet and storing the result.
Modern AI tools can make such integrations even more accessible. With documented digital interfaces, scripts connecting printhead control, fluidics and motion systems, the dropwatcher can be created with significantly less programming effort. As a result, the dropwatcher can become an integrated sensor within a larger automated process, rather than a stand-alone instrument.
Dropwatchers have traditionally been expensive for good reasons. High-quality optics are costly. But perhaps the most important factor is that these specialised measurement systems are typically manufactured in comparatively low volumes.
droptical took a different approach. The company considered original equipment manufacturer (OEM) integration and higher production volumes. As a result, camera, electronics and mechanics were designed for efficient manufacturing and scalability from the beginning.
The price difference is therefore not achieved by compromising on measurement quality. Developing the camera platform in-house allows components to be selected specifically for dropwatching instead of building the system around expensive standard components.
The result may seem counterintuitive – a smaller and more affordable dropwatcher can simultaneously deliver higher performance and finer pixel resolution. Miniaturisation, performance and cost optimisation can thus be consequences of the same development approach.
“The dropwatcher can become an integrated sensor within a larger automated process”
This architecture has developed into a product family covering laboratory work, portable measurements, next-to-line applications and direct integration into production equipment.
The technological foundation remains the same. The long-term idea behind droptical is that dropwatching should no longer be a specialised tool used only occasionally in a laboratory. It should become compact, open and easy enough to integrate to evolve from a development tool into a natural part of the jetting process itself.
By combining camera technology, integration and scalability in a new way, droptical is setting a new benchmark for dropwatching. In the third part of this series, the focus will shift from the technology to what can be achieved in real-world applications