A method of calibrating a PAI system (401-413) is described. The method includes a signal processing unit (404) determining optical fluence at voxels within arteries of a human or animal, and interpolating from these measurements to provide a fluence map with a fluence value for all voxels of interest. The system (404) stores the fluence map for subsequent use in making PAI measurements. The arterial optical fluence may be determined on the basis that the arterial oxygen saturation (SaO2) is the same throughout the arterial part of the circulation system.

The invention relates to a method for determining VIV or Vv concentration in mixtures of VIV and Vv solutions, the method comprising the steps of determining the absorbance of the solution at at least one wavelength; and calculating the concentration of the VIV and Vv solution based on the absorbance. In one embodiment the VIV, Vv and/or total vanadium concentration in a solution is calculated based on the fact that the absorbance at a specific wavelength can be predicted by taking into account the formation of vanadium complexes.

An OCT imaging system (100) comprising a radiation emitter (SLD), a radiation receiver CCD), an interferometer (FC, PC, X-Scan, Y-Scan), a controller (COMP) which controls the emitter and processes received radiation data according to OCT to provide an output image. The controller (COMP) forms a spectrum of spatial frequencies along the depth direction. It calculates from the spectrum local spectra of spatial frequencies or periods along the depth direction for individual volume elements along the depth direction. It translates the local spectra of spatial frequencies or periods along the depth direction into the OCT image domain. It maps the local spectra into the volume elements to provide sensitivity on the nano-scale whereas the volume elements are in the micro-scale. The controller calculates information parameters from the translated and mapped local spectra. Thus the system (100) achieves nano-scale sensitivity although the volume elements are at the micro-scale.

A power generating system (1) has an offshore remote system (2-11) and an onshore local delivery system (15-20) adapted to be connected to an electric power grid (30). The remote system has at least one synchronous generator (4) driven by a prime mover (3), a remote bus (10) to which the synchronous generator is linked, and a controller (39-41). A frequency wild transmission system (15) links the remote system to the local delivery system. The remote system and the transmission system deliver power without AC-DC- AC conversion, and the local delivery system comprises a back-to-back converter (20) to perform AC-DC-AC conversion for grid code compliance. In one example there are at least two prime movers, a synchronous generator (4) coupled to each prime mover, and said synchronous generators (4) are connected to the remote bus (10) so that the remote bus provides a common connection point. The remote system controller is adapted to match voltage and frequency of power delivered from all of the synchronous generators to the remote power bus for remote frequency wild synchronisation of the synchronous generators.

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