An epifluorescence microscope setup has been developed and tested featuring Raman and multiplex-CARS capabilities. Samples were stored in 96 multi well plates on a sample stage with triaxial piezo drive stages for sample scanning. Raman excitation was achieved by a 785 nm laser with up to 100 mW output power and below 1 pm wavelength bandwidth (FWHM). Multiplex CARS was excited by a laser system providing 1064 nm primary pulses with 1 ns duration and broadband “white” anti-Stokes radiation (1100 nm … 1700 nm) generated by a non-linear optical fiber. Repetition rates around 30 kHz resulted in an average excitation power of up to 200 mW. For both excitation principles the signal was captured by a Raman spectrograph (Ocean Insight QEPRO) designed for 790 nm … 1070 nm spectral range, resolution below 1 nm and a thermoelectrically cooled detector for a good signal-to-noise ratio (SNR) to detect weak RAMAN and CARS signals. First measurements have been performed on selected samples and promising results have been achieved.
Spectral analysis has gained a lot of interest throughout the last decades. Nondestructive and non-contact evaluations can provide multiple information: appearance and composition, but also more complex details, which can be accessed by means of sophisticated methods like fluorescence or Raman scattering. Spectrometers have been widely used for the UV to NIR spectral range. There are applications, where a broad spectral range is beneficial. Typically, the spectral range of a grating based system is limited by higher diffraction orders. Either one decade can be detected or order filters have to be applied to discriminate different orders. A novel concept for a broadband spectrometer is the use of a scanning mirror device to illuminate a fixed grating. Due to the optical path inside, the double wavelength range can be addressed for the identical MEMS deflection. Two or more detectors, each optimized for the relevant spectral range, can be placed in the setup. A first sample of a scanning mirror micro spectrometer (“SMMS”) has been realized and tested successfully. In the NIR spectral range from 1000 nm to 1900 nm a resolution of 10 nm (FWHM) has been achieved. Application examples can be found in the field of agriculture - soil, plant growth and watering, directly leading to food, e.g. ripeness and freshness. Spectrometer with broad spectral range enable simultaneous detection of appearance (color) and composition (NIR); also fungus and aflatoxins can be detected by means of UV to VIS fluorescence. Similar task arise in textile, recycling and other fields where color, composition and conditions are of interest.
Additive manufacturing using two-photon polymerization (TPP) lithography is increasingly used in industry and research. Parameter sweeps of cuboid structures fabricated using TPP lithography were investigated across the parameters of the laser power and scan speed to find dependent mechanical material properties. The employed photoresists were examined using Raman spectroscopy to find the degree of conversion (DC) of monomer to polymer, and subsequently, micro- or nanoindentation was used to find Young’s modulus (E). For the photoresist IP-Dip, the attained DC and E ranged from 20% to 45% and 1 to 2.1 GPa, respectively. The results were compared with reports found in the literature. For IP-Q, the attained DC and E ranged from 53% to 80% and 0.5 to 1.3 GPa, respectively. The characterized properties of IP-Q manifest as the current state of knowledge of the material.
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