Lasers for Life Sciences, Measurements & Displays

... with output powers up into the watt range are needed in biomedical applications such as dermatology, ophthalmology and flow cytometry. For medical treatments such as photothermolysis of dermal vascular lesions or photocoagulation in ophthalmology, a wavelength around 577 nm is ideal because there is a clear absorption peak of oxyhemoglobin here. Additionally, melanin absorption and scattering in the epidermis is reduced compared to shorter wavelengths. Currently, dye or copper bromide lasers are mostly used, which have disadvantages such as inefficiency, large dimensions, toxicity, complexity or high maintenance cycles.

... enable the treatment of eye diseases by laser coagulation. They thus also address the two main causes of blindness: diabetic retinopathy (DR) and age-related macular degeneration (AMD). In the field of sensor applications, diode lasers are also used for point-of-care (POC) technology on patients, for example to research, predict and diagnose chronic inflammatory respiratory diseases. These include asthma and chronic obstructive pulmonary disease (COPD).

... enable fast, stain-free and non-invasive tissue diagnostics. For this purpose, we have developed diode lasers that are wavelength-stabilized at 460 nm. They open up new possibilities for clinically evaluating tissue even during a surgical intervention with functional Raman images, for example to visualize tumor margins in cancer medicine. This allows surgical interventions to be shortened and made more precise.

... are needed in medical imaging, but also in scientific imaging, virtual modeling, and for art and advertising. Digitally generated static holograms have now matured to the point of commercial applications, but currently the available highly coherent laser sources prevent widespread use. They are still too large and complex, not efficient enough and too expensive. In addition, a wet chemical process is still required to develop the holograms.

Together with our partners, we therefore aim to develop prototype laser printers for the production of digital reflective holograms. The possibility of three-dimensional representation opens up the fast and clear analysis of complex relationships. Medical applications in particular can benefit from holographic imaging due to the simple visualization of entire organs or tissue structures. This will be based on two technologies to be developed: RGB laser modules with sufficiently high coherence properties for holography and a chemistry-free development process for the holograms to be printed. The holographic laser printers based on this should be economical and able to achieve a correspondingly high share of the global market for digital holograms.

The color space visible to the human eye cannot be completely reproduced from the three primary colors red, green and blue. Yellow laser light can be used to additionally cover a larger area of the color space and improve color reproduction. However, yellow light cannot yet be generated directly with semiconductor lasers. We have therefore developed special laser light sources based on laser diodes emitting in the near-infrared range from 1120 nm to 1190 nm. By means of frequency doubling, their radiation is converted into the yellow spectral range from 560 nm to 595 nm. Here, optical output powers between 100 mW and 1.5 W are provided with a nearly diffraction-limited beam (M² < 2). The modulation capability is in the MHz range.

True flying spot displays produce sharp images regardless of the distance and surface shape of the screen. We have developed special tapered lasers for the red spectral range from 635 nm to 660 nm, emitting output powers of 500 mW at 635 nm and up to 1 W at 660 nm. The beam quality is almost diffraction limited (M²<3) and modulation speeds up to the MHz range are possible.