IT’S POSSIBLE SESSIONS – LASER WORLD OF PI

The accuracy of the scanner decreases with the deflection angle. In case of combined motion not the full angle is utilized, therefore the accuracy of the system in the combined motion case is higher.

We are talking about a system with high accuracy on the order of 5 µm. If there is an unwanted movement of the stage, the process result will not meet expectations. Therefore, such a compensation is not implemented. Instead the scanner and the stage receive a path that they can follow exactly.

The software will find the optimum pattern and optimum path with the least amount of time to process the entire workpiece. The individual beams cannot be controlled on the fly, yet.

For a system with 3 µm accuracy a calibration is necessary in any case.

The SPC GUI, which was presented, is capable of running XL SCAN. Many of our users program their own interface to our API.

In that case, we could use a height sensor in combination with stages and scan the surface of the sample. SPC has the Z-map command that can automatically transform the geometry based on this measurement or export the surface as a 3D CAD and then project the 2D pattern on top of it.

The technology to put electrical contacts on the plastic part was developed by the Center for Physical Sciences and Technology in Lithuania and DMC software was used to make the actual part using the 5 axes setup. It is a promising technology, allowing to deposit metal tracks on a very wide range of surfaces much cheaper than it is done currently.

Yes, SPC has tools to calibrate cameras, scanners, and stages. So, the whole system can be calibrated from scratch using SPC.

Yes, 5-axis functionality has been recently released. Individual projects should be discussed case by case.

It is quite easy as the user is operating objects and process specific commands to define his process. A student who understands what parameters he needs to control to make a process can learn to use it very quickly, you do not have to worry about individual component control.

SPC is an ACS product and works only with ACS/PI motion controllers. As to other hardware, it works with a wide range of scanners, cameras, lasers, and other equipment.

SPC allows defining the delays for each object. So, if the speed changes, the delay can be changed as well. Also, using a simple recipe with a loop and a couple of objects, SPC allows to easily test a wide range of delays and build up a library of parameters for different conditions.

This question could not be answered by a fix value. This depends on the weight of different optimization targets, the sheet thickness, and the used laser beam. If you want to enlarge the cut kerf width to enable automation of unloading the machine, we have to enlarge the perpendicular amplitude. All in all the XY oscillation should be in a range between factor 1 to 3 of the focus diameter. In case of Z the amplitude should achieve a virtual Rayleigh length of sheet thickness to cut minus the real wavelength. For example, the used laser beam has a Rayleigh length of 3 mm. For cutting 10 mm thick sheets, an amplitude of 4 mm is useful (2*3mm + 4 mm = 10 mm).

Additional costs has to be answered by PI. I can say something about the savings. If we talk about a process speed, an increase of 50% is possible. That means we can cut 50% more by same running costs.
The running costs consist of energy (3-5 € per hour saving 1.5-2 € per hour). For fusion cutting we use compressed nitrogen. Thick sheet needs up to 2m³/min  120 m³/h. The m³ nitrogen cost 15 ct. If we can save 50% gas, a saving of up to 9 € is possible. I expect a reduction of running costs between 5 and 10 € per hour for thick sheet fusion cutting.
Further additional effort for dross removal could be saved.

The lifetime of the melt pool gets enlarged. The gas, which was "stored" during casting process transforms in the melt pool to small bubbles. The longer lifetime gives the bubbles more time for flooding and avoids to be caught in the weld seam. Further, the bubbles get steered out of the process zone. The chief uses a spoon, we use the laser beam. This supports the flooding, too.

Up to now it is the equipment or the approval from system deliver side. XY is approved for 3 kW, we use in lab 10 kW by monitoring the devices. Up to now, no problems caused by the beam shaping equipment.

Engraving of transparent material was one demonstration application during the development project. The equipment can upgrade every laser equipment no matter which wavelength, peak power, or intensity.

Effective cooling of the piezo actuator needs direct contact of the cooling medium with the whole actuator stack, the piezo needs to "swim" in the cooling medium. Therefore, water ist no option. If any, then oil (a medium which is also not available at the system). On top: Incompressible oil might affect the dynamic performance.

The laser power of 3 kW was chosen for comparative reasons with other research projects. The limiting factor for laser power is the reflectivity of the optical element. Absorbed heat affects glue stability.

We know that air turbulences can affect the beam quality. As a counter measure, we can seal the system with airtight membranes in order not to disturb the optical path.

In this use case repeatability is more important than absolute accuracy. The hysteresis is very repeatable. Therefore, we drive the systems open loop and gain additional system frequency bandwidth.

The piezo tip/tilt mirror platform is a two axis system with only one mirror. This allows for much smaller form factors compared to a galvo scanner (only ~ 1/8th of integration space). On the other hand, the piezo tip/tilt has a much smaller angular travel range, yet this disadvantage can be neglected due to the small travel range needed for dynamic beam oscillation.
Comparative tests in cutting performance tests at the Fraunhofer IWS showed no difference in the observed process window, but you still have the advantage of a small integration space.

It is a question of design. The systems have been developed for 90° angled cutting heads, this means 45° angle of incidence. The coatings have been optimized for this angle. But they can be changed, if needed.
Maximum laser power is also a design question, taking the reflectivity of the optical element into account.

The advantages, we had a look at, were mostly given if the material thickness was larger than the focal depth/Rayleigh length of the beam. But there might be processes in micro laser materials processing, were an oscillating beam is beneficial.

This depends on the desired resolution. In principle, almost any number of cells could be printed at once by increasing the size of the transferred droplet. However, more than 1000 cells per droplet is usually not practical for tissue engineering and some applications require that only a few cells per droplet be printed. It must be taken into account that the speed at which printing can be performed is directly dependent on the resolution.

Different cell types take on very different forms in their respective tissues. Some are rather compact, keratinocytes for example, while others, such as neuronal cells, have long extensions; the tissue structures they form also differ significantly. The structure of the scaffolds should be adapted to the needs of the particular cell type so that they can grow optimally and cross-link to form tissue. Our scaffolds are computer designed and laser fabricated so that their 3D geometry can be completely defined. We can optimally adapt the scaffold geometry to the respective cell type.

Basically, you have to distinguish between the pure printing time and the time for the entire process. Of course, the cells have to be grown over several weeks or months. When printing an organ, these would then have to be dissociated and made available in time. After that, a more or less automated material feed would still significantly affect the overall time. It would be crucial to be finished with the entire process before cells die due to inadequate supply after several hours; however, this time span can be extended biochemically.
The pure printing time can be estimated as follows: A 100-kHz laser and 10 cells per droplet can print one million cells per second, or 3.6 billion cells per hour. Since the laser repetition rate can also be higher, and the average cell count per droplet could probably be slightly higher than ten for many organs, this number could be even higher; especially if more than one print head is used.
For organs, total cell counts are reported to be in the single or double-digit billions, so that would translate to a few hours of pure printing time. This is a simple estimate and currently not feasible, but it shows that with further optimization and automation, printing entire organs is not unrealistic in the future.

The XL Scan technology is definitely a very interesting technology. Already today, the size of our scaffolds is limited less by the positioning technology itself than by the printing time and the XL Scan technology offers an attractive opportunity to make the process even faster and more technically intelligent.

The lasers used today for cell printing, are either in the UV or NIR spectral range, have repetition rates from 10 Hz up to the 100 kHz range and usually apply pulse energies in the two- or three-digit µJ range.

No, the motion trajectory generation occurs on the motion controller whose internal processor does the processing. This avoids the need to install a real-time extension or special software on the PC, which can problematic due to windows software updates and may require a strict control of the PC hardware or windows updates.
For the use of the SPC CAD/CAM software, if the job involves intricate 3D detail, then a faster PC may be required to reduce the process time for converting the drawing to a motion profile.

Choose a higher specified stage set from our choices in IMAS. Ensure the stage selection has linear mapping (1D calibration). Apply 2D mapping. This will be an option at the end of the year.

Accuracy is the combination of the stages and galvo, so choose a good scanner. There are new models that are offering single digital micron performance and much better thermal properties.
Ensure that the stage and the galvo fields are aligned, by ensuring that field size and alignment are matched.
There are tools available to automate this process in the SPC CAD/CAM software.
The reference for the system accuracy is normally the stage, so having a stage system is good quality is very important.
You could use a smaller scanner field of view if the process throughput allows, this would also reduce the effect of yaw in the stages as this can not be mapped out in terms of field rotation, and the error increases from the stage carriage center.