Abstract: A magnetic field gradiometer for determining a magnetic field gradient includes at least one excitation light source for emitting excitation light, and two spatially spaced-apart measuring areas for magnetic field measurement. Color centers in diamond are arranged in the two measuring areas. The color centers emit fluorescent light upon excitation using the excitation light. The magnetic field gradiometer further includes at least one microwave emitter for applying at least one microwave field to the spatially spaced-apart measuring areas, two detectors for detecting the fluorescent light from the two spatially spaced-apart measuring areas, and an evaluator for determining the magnetic field gradient based on the fluorescent light detected by the two detectors. The two measuring areas are configured as freestanding measuring waveguides of a common diamond crystal. The diamond crystal is used as a substrate for the measuring waveguides.

Abstract: A sensor arrangement for detecting features of particles includes an emitter for emitting electromagnetic radiation, a detector for receiving the electromagnetic radiation emitted from the emitter and for providing detector signals based on the received electromagnetic radiation, and a measurement volume irradiable by the electromagnetic radiation emitted by the emitter. The measurement volume is configured for receiving particles flowing therethrough. The sensor arrangement further includes a digitizing unit for digitizing the detector signals, and an evaluation unit for evaluating the detector signals. The evaluation unit stores a trained algorithm for machine learning. The algorithm is configured for determining at least one feature of the particles based on the detector signals.

Abstract: A method for calibrating a particle sensor includes focusing a laser beam on a calibration plane for generating a calibration intensity distribution in the calibration plane. A calibration plate is arranged in the calibration plane. Contrast regions for modulating an intensity of the laser beam are formed on the calibration plate. The method further includes moving the calibration plate and/or the calibration intensity distribution in the calibration plane, recording at least one intensity signal of the laser beam, following passage through the calibration plane, and calibrating the particle sensor by evaluating the at least one intensity signal.

Abstract: A method for joining an optical crystal to a substrate includes radiating a pulsed laser beam through the optical crystal or through the substrate onto a surface of an intermediate layer between the optical crystal and the substrate, and forming a fusion zone in the intermediate layer between the optical crystal and the substrate by the radiation of the pulsed laser beam, thereby integrally joining the optical crystal and the substrate.

Abstract: A method for forming at least one freestanding microstructure on a diamond crystal includes the step of removing material from the diamond crystal so as to form a structured surface, wherein the removing of the material includes creating at least two trenches, each trench having a bottom and two side walls and wherein adjacent side walls of the at least two trenches form side walls of the structured surface. The method also includes the steps of depositing at least one masking layer on the structured surface, removing at least a portion of the at least one masking layer from the bottom of each of the at least two trenches, removing additional material from the diamond crystal at least along the side walls so as to deepen the trenches, and undercutting the diamond crystal so as to form the freestanding microstructure.

Abstract: A method for producing at least one optically usable microstructure, in particular at least one waveguide structure, on an optical crystal is provided. The method includes irradiating a pulsed laser beam onto a surface of the optical crystal, moving the pulsed laser beam and the optical crystal relative to one another along a feed direction in order to remove material of the optical crystal along at least one ablation path in order to form the optically usable microstructure. The pulsed laser beam is irradiated onto the surface of the optical crystal with pulse durations of less than 5 ps, preferably less than 850 fs, more preferably less than 500 fs, in particular less than 300 fs, and with a wavelength of less than 570 nm, preferably less than 380 nm.

Abstract: A sensor arrangement characterizes particles. The arrangement has an emitter with a laser source that generates a laser beam; a mode converter that generates a field distribution of the laser beam, which at each position has a different combination of a local intensity and a local polarization direction of the laser beam; and focusing optics that focus the field distribution of the laser beam onto at least one measurement region, through which the particles pass, in a focal plane. A receiver is also provided with analyzer optics configured to determine polarization-dependent intensity signals of the field distribution of the laser beam in the at least one measurement region; and an evaluator configured to characterize the particles, including the particle position, the particle velocity, the particle acceleration, or the particle size, using the polarization-dependent intensity signals.

Abstract: A sensor arrangement characterizes particles. The arrangement has an emitter with a laser source that generates a laser beam; a mode converter that generates a field distribution of the laser beam, which at each position has a different combination of a local intensity and a local polarization direction of the laser beam; and focusing optics that focus the field distribution of the laser beam onto at least one measurement region, through which the particles pass, in a focal plane. A receiver is also provided with analyzer optics configured to determine polarization-dependent intensity signals of the field distribution of the laser beam in the at least one measurement region; and an evaluator configured to characterize the particles, including the particle position, the particle velocity, the particle acceleration, or the particle size, using the polarization-dependent intensity signals.

Abstract: A laser light source includes a nonlinear optical medium and a pump laser source configured to generate a pump laser beam to form a signal beam and an idler beam in the nonlinear optical medium by parametric down conversion. The laser light source further includes a seed light source configured to generate a seed signal beam and/or a seed idler beam having a coherence length lesser than a coherence length of the pump laser beam, and a superpositioning device configured to superposition the seed signal beam and/or the seed idler beam with the pump laser beam for joint coupling into the nonlinear optical medium.