The following invention represents a possibility to identify infusions when administered by an injection pump. The method involves a combination of Raman spectroscopy and refractometry. Both methods of analysis are based on instrumental analysis. Furthermore, algorithms are used for the evaluation which can be assigned to indirect hard modelling and statistics.

The problem of incorrect medications and infusion solutions in hospitals is well known. With a clear identification, for which both Raman spectroscopy and refractometry are necessary, wrong medications can be detected by the invention presented here and can then be prevented by medical personnel. When comparing the results of the analysis with the hospital IT, a further service (such as e.g. drug intolerance) is available which can trigger an alarm. So far, all attempts to reduce medication errors have been based on non-technical solutions, for example the use of barcode systems. (Figure: Study of an automated analyzer for the identification of infusion solution in a syringe).

 

 

 

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An alternative concept for mode coupling for the generation of ultra-short laser pulses will be presented. Based on the Kerr effect in thin-film systems, the Kerr band switch in a dielectric layer system implements an ultra-fast and loss-free switch concept at low cost, which covers almost the entire spectral range. This concept has high damage thresholds and, compared to semiconductor absorbers, absorbs only very small amounts of radiation energy and thus heats up only slightly.

 

Ultra-short pulse lasers (USPL) have become increasingly important in recent years. Especially in medical, industrial or life science applications they are gaining more and more importance. Compared to laser systems with longer pulse duration, they minimize the thermal damage of the material during processing by the fast energy input, which is shorter than the thermal diffusion of the energy through the material to be processed. Therefore, they enable significantly higher precision than would be the case if longer pulse duration were used. This minimizes thermal damage zones and enables the production of precise structures on a nanometer scale. Nevertheless, the application field of USP lasers is often limited by their complex structure and the associated high price. In addition, the currently available USP laser sources can often only generate wavelengths in the infrared spectral range. The general laser principle for generating short laser pulses is based on mode coupling, which can be achieved with a variety of technologies and components. In USP systems commercially available today, so-called SESAMs (Semiconductor-Saturable-Absorber Mirror) are generally used for mode coupling. These switches are based on the saturable absorption of a semiconductor layer, which in most cases consists of InGaAs mixtures and is therefore limited to narrow spectral ranges due to the material-specific band edges. In addition, the switching of the SESAM is based on the absorption of part of the laser light, which leads to undesired heating of the component at high power levels.

 

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The newly developed method provides a faster and more efficient way for producing gratings - by ablation of small amounts of material - on glass surfaces. Thereby, the economic labeling of glass with patterns causing diffraction becomes possible. These patterns shimmer in different colors if observed from different angles.

(Image: A micrometer scaled grating on a glass surfaces causes diffraction and creates a colorful and shimmering structure. (Source: Dr. Jürgen Ihlemann, LLG) )

According to the above mentioned challenges, the aim of the inventors was to develop a method for fast and efficient microstructuring of glass.
The developed process uses plane laser ablation by excimer lasers, however, with low-loss optical components and methods. The whole beam profile of the laser is being used, resulting in higher laser output and increased efficiency and contrast. With the newly developed method it is now possible to move the workpiece continuously, as needed in industrial production or processing. Laser pulses are triggered whenever the workpiece has moved by one or multiple periods of the desired grating. Additional devises that create a relative movement between the laser and the workpiece, e.g. a scanner, are not required. If the grating has to be tilted towards the feed direction, only the increment between two pulses has to be adjusted to the line distance in feed direction. Optimally, the maximal repetition rate of the laser can be used.
With this process, it is now possible to produce gratings on a micrometer scale within a very short time frame on workpiece surfaces - especially glass surfaces. The produced structure can fill a predefined shape. The resulting shape then appears colorful and shimmering, similar to what is known from holographic markings. Alternatively, it can be used to define the wavelength-dependent reflection or transmission of a surface.

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Hybrid plasma-laser micro-structuring provides a tool for treating fused silica without the need for a time consuming preconditioning of the surface or the use of expensive vacuum-UV- respectively mid-wavelength-IR-lasers. The use of a hydrogenous plasma prior to the ablation process causes a temporary increase of the absorption in a more easily accessible wavelength region.

Laser ablation is a surface treatment method and is preferably used to remove thin layers or drill narrow holes. As elegant as this technique might be, it demands a sufficient absorption within the treated material or surface. Fused silica however is almost transparent in a range between 200 nm and 2000 nm where laser ablation is usually carried out. As of today there exist two possible solutions to bypass this disadvantage: On the one hand one can add a layer with a higher absorption coefficient onto the transparent surface before ablation but has to make sure that this layer can be completely removed afterwards. On the other hand it is possible to decrease/increase the laser wavelength beyond/above absorption threshold or amplify the energy density of the laser beam. Both solutions increase efforts and thus costs. (Image: Fused silica after conventional laser ablation treatment (left) and after the herein introduced Hybrid Plasma-Laser Micro-Structuring (right). It can clearly be seen, that both contour accuracy and surface roughness are improved by the hybrid technique. )

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The invention describes a simple way of performing Image Scanning Microscopy (ISM) purely optically. It is not necessary to reconstruct the final image from a multitude of individual acquisitions. Instead, the final image is projected directly onto the camera chip. The method is suitable for confocal microscopy as well as for 2-photon microscopy.

Image Scanning Microscopy was developed during the last years and improves the lateral resolution by a factor of 1.6 in comparison with confocal Laser Scanning Microscopy (cLSM). The principal of the method is similar to how the improved resolution in structured illumination microscopy is obtained.

Previously, the disadvantage of ISM was, that for each scan position of the excitation laser an individual image on the camera chip had to be acquired. Subsequently, the final image was calculated by combining all sub-images. Although with this approach ISM was already capable of reaching a significantly higher resolution than cLSM setups, it was also much slower.

New developments have shown that optical ISM without computer aided reconstruction is possible (Optical Photon Reassignment – OPRA). Unfortunately, OPRA demands quite complex optics and it is difficult to upgrade existing cLSM setups. In addition, excitation and emission light pass through the same optics which makes it difficult to apply the method in 2-photon microscopy. 

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As disposable products, waveguide-based biochips offer a wide of possibilities, but relatively high manufacturing costs often make their use uneconomical. The most important cost factor is the structuring of the chip, which enables effective coupling of the laser light. A novel coupler makes it possible to couple light into chips without structuring.

Planar thin film waveguides have become indispensable tools in various fields such as telecommunication technology, biosensors and material characterization. In biosensor technology, for example, they can be used to efficiently excite dye molecules and to follow changes in the surface coating extremely precisely. A decisive point in the use of waveguide-based biochips is the coupling of the laser beam into the waveguide. Due to the low layer thickness and the high refractive index, coupling via the end surface of the waveguide or prism coupling is not feasible. The only practical method to date is light coupling via so-called grating couplers, i.e. gratings with periods in the sub-micrometer range that are structured in the waveguide using an etching process. This grating is responsible for a large part of the costs used to manufacture the chip. Since biochips are generally disposables, a cost reduction is very interesting here.

Figure: Function principle of evanescence field microscopy: The light of a laser is coupled into a microscope slide via a grating structure. The evanescent field stimulates optical transitions in molecules located on the surface of this carrier. (Source: Fricke-Begemann)

 

 

 

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The newly developed method improves the monitoring and control process for beam welding. In contrast to most commonly used methods, the new monitoring process is root sided, i. e. it takes place on the back part of the workpiece. Furthermore, the invention describes a monitoring device optimized for beam welding. Beam welding using the invention avoids incomplete fusion at the weld interface and increases the stability of the weld joint.

Macro material processing via beam welding puts high demands on the alignment and positioning accuracy of the system. Typically the welding process is monitored at the upper side of the workpiece where the optical analysis of the keyhole provides a measurement for the quality of the weld. However, incomplete fusion cannot be excluded by only monitoring the upside of the workpiece. It is, for example, not possible to register a tilt between the beam and the joining gap. Already small angles lead to incomplete fusion if the material is thick. But not only a tilted beam can lead to incomplete fusion - also the geometry of the workpiece might introduce an angle between the beam axis and the joining gap. Such an angle results in incomplete fusion at the root area even if the process is monitored on the upper side of the workpiece. The error can only be detected by monitoring the welding from the root side. Some workpieces do not allow for a perpendicular alignment between workpiece and beam axis, in this case monitoring the upside of the workpiece is equally insufficient. Finally, besides the need to adjust the alignment of the beam it is also often necessary to adjust the power of the laser beam in order to maintain the necessary welding depth. Figure: Construction model (left) and realization (right) of the root sided process monitoring system. (Image Source: Stefan Kaierle, LZH)

 

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The invention relates to the usage of a tunable, resonant electromagnetic field for both, the targeted fabrication of structures with dimensions smaller than the used beam diameter and the targeted fabrication of ultra small particles. Therefore, the electromagnetic field that is created by an ultra short laser pulse on the surface of an object is superposed with an external field to achieve a resonance rise specific to the processed material.

Figure: Setup for resonant surface treatment using a laser and an external field. Via two electrodes which are located on the work piece (left- and right-hand side) of the area to be treated, a tunable electrical field can be applied. This field superposes the electro-magnetic field of the laser making it much easier to reach the material dependent resonance condition. (Source: V. Schütz)

The conventional fabrication of micro- or nano-structured surfaces is of great interest for a huge amount of industrial or R&D applications. Using (ultra) short laser pulses, so called LISOS ("laser induced self organizing structures") can be produced quite easily. Since the process is taking place in close vicinity to the ablation threshold, small laser intensities suffice to fabricate these LISOS. However, to process larger areas the average laser power needs to be increased to several kilowatts. Taking today's state of the art, this results in high acquisition and maintenance costs for the needed laser systems consequently raising the inhibition threshold in industry.


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The invention deals with laser transmission welding of glass fiber reinforced polymers or unreinforced polymers with CFRTP. The absorption of the laser beam occurs mainly on the carbon fibers, thus, adding additives for absorption is not necessary.

Different joining techniques for reinforced composites exist. Among them are the use of adhesives, rivets, induction welding, electric resistance welding or ultrasonic welding. All the available processing techniques have certain limitations. Adhesive bonds need extensive steps for surface preparation and cannot be tested for stability without destruction. Induction welding works only on conductive materials. Electric resistance welding uses a conductive mesh at the welding area which constrains the achievable geometries and remains in the material after welding. The necessity of adding absorbing additives to the joining partners is also a frequent problem with laser transmission welding. Figure (Scheme of the laser transmission welding (Source: Peter Jäschke, LZH))

 


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