The Innoslab amplifier comprises a diode-laser partially end-pumped thin slab crystal and a folded single-pass optical amplification path. While this configuration differs in many respects from other slab amplifiers, it shares characteristics with partially end-pumped rod amplifiers. It combines outstanding thermal management, efficiency, and beam quality in the 100 W to 1 kW power range. In this paper, we review amplifiers for a wide range of operation regimes and laser materials.
The design of freeform lenses and reflectors allows to achieve non-radially symmetric irradiance distributions whilst keeping the optical system compact. In the case of a point-like source, such as an LED, it is often desired to capture a wide angle of source light in order to increase optical efficiency. This generally results in strongly curved optics, requiring both lens surfaces to contribute to the total ray refraction, and thereby minimising Fresnel losses. In this article, we report on a new design algorithm for multiple freeform optical surfaces based on the theory of optimal mass transport that adresses these requirements and give an example of its application to a problem in general lighting.
More and more lighting applications require the design of dedicated optics to achieve a given radiant intensity or irradiance distribution. Freeform optics has the advantage of providing such a functionality with a compact design. It was previously demonstrated in [Bäuerle et al., Opt. Exp. 20, 14477-14485 (2012)] that the up-front computation of the light path through the optical system (ray mapping) provides a satisfactory approximation to the problem, and allows the design of multiple freeform surfaces in transmission or in reflection. This article presents one natural extension of this work by introducing an efficient optimization procedure based on the physics of the system. The procedure allows the design of multiple freeform surfaces and can render high resolution irradiance patterns, as demonstrated by several examples, in particular by a lens made of two freeform surfaces projecting a high resolution logo (530 × 160 pixels).
A Nd:YAG slab is partially end pumped by a diode laser stack with three diode laser bars. The pumped volume has a rectangular cross section. A hybrid resonator, which is stable in the plane of small dimension and is off-axis unstable in the plane of large dimension of the gain cross section, was used to yield highly efficient laser operation at diffraction-limited beam quality. The laser design and experimental results are reported.
Asymmetric Incremental Sheet Forming (AISF) is a relatively new manufacturing process. In AISF, a CNC driven forming tool imposes a localized plastic deformation as it moves along the contour of the desired part. Thus, the final shape is obtained by a sequence of localized plastic deformations. AISF is suitable for small series production of sheet metal parts as needed in aeronautical and medical applications. Two main process limits restrict the range of application of AISF in these fields. These are the low geometrical accuracy of parts made from titanium alloys or high strength steels and, for titanium alloys, the limited formability at room temperature. In this paper a new concept for laser-assisted AISF is introduced including the required components. Furthermore, the CAX tools used for programming the NC path for the forming tool and the laser spot are illustrated. First experimental results show that the formability of the alloy Ti Grade 5 (TiAl6V4), which is usu ally used in aeronautic applications, can be increased
The transmitted double-beam interference microscope was used to determine the dry weight per unit biovolume of single living cells, trichomes and mucous sheaths of eight mainly terrestrial species of cyanobacteria from cultures and in situ samples. The minimum dry weight was 131.7 fg mm À3 whereas the maximum was 459.2 fg mm À3 from single cell measurements. The average (AESD) of all 72 measurements was 265 AE 46 fg mm
À3. This value is lower than the average calculated from literature data by a factor of 1.8. Additional elemental measurements of the amount of carbon resulted in an average value (AESD) of 48 AE 3% of dry weight, which corresponds with literature data. Thus we recommend a new conversion factor of 0.127 for biovolume (mm 3 ) of cells to mg carbon, which could be used for cyanobacteria in respect to overall biomass calculations. Dry weight measurements were also carried out on the mucous sheaths of both trichomes (Phormidium) and coenobia (Gloeocapsa). Dry weights per unit volume of the sheaths varied greatly, ranging from 28 fg mm À3 (Phormidium) to 70 fg mm À3 and even 210 fg mm À3 (Gloeocapsa). In Gloeocapsa the dry mass of sheath material of a single coenobium exceeded the cellular dry weight 6-fold. As the interference microscopical technique is unique in its ability to determine dry masses of single living untreated cells, even in complex environmental samples, we intended to develop this method to make it available to a broad range of applications.
Aeronautical applications often require small batches of large-scale sheet metal parts made from titanium and its alloys. Due to the low formability of titanium at room temperature, warm forming processes are necessary. Incremental sheet metal forming (ISF) is suitable for production of prototypes and small batches as well as large-scale parts. A short review of the experimental work done by international scientists in the field of warm ISF including stationary and moved temperature sensors will be presented mostly applied from the backside of the sheet metal. The present paper shows a new approach for a tool setup including a thermocouple inside of the tool. Hence, the sensor for temperature measurement was moved with the forming zone. Furthermore, a suitable closed loop control including a PID controller will be presented. The characteristics of the controller will be discussed. By means of two different warm ISF processes (ISF with resistance heating and laser-assist ed ISF), the applicability of the developed setup will be analysed and evaluated. It will be shown that the experimental setup is capable to ensure minimal temperatures needed to ensure adequate formability of Ti grade 5
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