Application of ODMR techniques with colour centres in diamond to temperature measurement in neurons G.Petrini, G.Tomagra, E.Bernardi, E,. Moreva, I.P.Degiovanni, P.Traina, P.Olivero, V.Carabelli, M.Genovese In this talk I will present our results that demonstrate for the first time the possibility of making localized temperature measurement with precision under 0.1 K in neurons by exploiting ODMR techniques. After a general introduction to ODMR techniques based on NV colour centers in diamond, I will present this breakthrough result Than could have huge possible impact to biology and medicine.
The manipulation of the transverse profile of light beams is ubiquitous in optics. However, the independent control and shaping of copropagating transverse spatial modes, i.e. spatial mode multiplexing, is a complex task. In recent years, a number of technologies have emerged, each tailored for different propagation mediums. We will give a thorough introduction to this topic, from its mathematical formulation to the different implementations available today, focusing on free-space shaping. We will present a few applications of this technology, both in the classical and quantum domains, focusing on the particular challenges brought by it, such as cross-talk.
Superresolution techniques based on intensity measurements after a spatial mode decomposition can overcome the precision of diffraction-limited direct imaging. We present both the experimental implementation of simultaneous spatial multimode demultiplexing as a distance measurement tool and the theoretical analysis of the actual sensitivity limits given the main experimental imperfection: cross-talks between channels. We demonstrate the distance estimation between two incoherent beams in both directions of the transverse plane, and find a perfect accordance with theoretical predictions, given a proper calibration of the demultiplexer. We show that, even though sensitivity is limited by the cross-talk between channels, we can perform measurements in two dimensions much beyond the Rayleigh limit over a large dynamic range. Combining statistical and analytical tools, we obtain the scaling of the precision limits for weak, generic crosstalk from a device-independent model as a function of the crosstalk probability and N.
Bessel beams are invariant solutions to the Helmoltz equation that can also propagate, with finite pulse energy at high intensity, in a quasi-invariant regime in transparent dielectrics. Homogeneous energy is deposited along a line focus by infrared ultrashort pulses. If the cone angle is sufficiently high, the laser-deposited energy density is enough to open nanochannels in glasses or sapphire with a single laser pulse. This has found applications in the field of glass cutting via the technique of "stealth dicing".
Here we address two important challenges in this field. First, high quality Bessel beams are essential for controlled energy deposition. Second, the maximal angle used up to here for channel drilling was 26° for 800 nm laser central wavelength. This enabled the formation of channels with diameters down to typically 300 nm in glass and sapphire. It is questionable if higher cone angles could also produce channels with potentially smaller diameters.
Here, we generate high quality Bessel-Gauss beams with a setup based on reflective, off-axis axicons. The Bessel zone exceeds 100 µm for cone angles up to 35 degrees. This corresponds to central spot diameter down to 0.5 µm FWHM. We qualified these beams with a 100 fs laser source centered at 800 nm wavelength. We report nanochannel drilling down to typically 100 nm over at least 30 µm length in glass.
Our approach opens novel perspectives for high quality Bessel beam generation but also for the highly confined laser-matter interaction for high precision processing of transparent dielectrics.
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