Abstract: A rotation detection apparatus, including: a beam source for emitting a beam of polarized light; a decohering arrangement for eliminating or reducing the degree of coherence between first and second independent polarization components of the polarized light to produce a decohered beam of polarized light; a detector for outputting a signal in dependence on the intensity of light incident thereupon, the detector arranged so that the decohered beam of polarized light is incident upon it; a polarizer for location in the path of the decohered beam of polarized light such that rotation of the polarizer relative to the decohered beam of polarized light results in a variation of the intensity of light incident upon the detector from the beam source and a corresponding variation in the signal output from the detector; and a processor for detecting the relative rotation based on the variation of the signal output from the detector.

Abstract: A rotation detection apparatus, including: a beam source for emitting a beam of polarised light; a decohering arrangement for eliminating or reducing the degree of coherence between first and second independent polarisation components of the polarised light to produce a decohered beam of polarised light; a detector for outputting a signal in dependence on the intensity of light incident thereupon, the detector arranged so that the decohered beam of polarised light is incident upon it; a polariser for location in the path of the decohered beam of polarised light such that rotation of the polariser relative to the decohered beam of polarised light results in a variation of the intensity of light incident upon the detector from the beam source and a corresponding variation in the signal output from the detector; and a processor for detecting the relative rotation based on the variation of the signal output from the detector.

Abstract: A frequency tuneable or chirped laser device is described that includes a laser cavity formed from a plurality of optical components. The optical components include a laser source for generating a beam of light, a spectral tuning element and one or more further optical components for directing the beam of light on to the spectral tuning element. At least one of the plurality of optical components is moveable in a first degree of freedom; such movement simultaneously altering the effective optical path length of the laser cavity and the tuning frequency of the spectral tuning element. The effective optical path length and the tuning frequency of the device are substantially insensitive to any movement of said at least one moveable optical component in degrees of freedom other than the first degree of freedom. This provides frequency tuning in which mode hopping is suppressed.

Abstract: A frequency tuneable or chirped laser device is described that includes a laser cavity formed from a plurality of optical components. The optical components include a laser source for generating a beam of light, a spectral tuning element and one or more further optical components for directing the beam of light on to the spectral tuning element. At least one of the plurality of optical components is moveable in a first degree of freedom; such movement simultaneously altering the effective optical path length of the laser cavity and the tuning frequency of the spectral tuning element. The effective optical path length and the tuning frequency of the device are substantially insensitive to any movement of said at least one moveable optical component in degrees of freedom other than the first degree of freedom. This provides frequency tuning in which mode hopping is suppressed.

Abstract: A surface sensing device includes an articulating head adapted for attachment to the spindle of a measuring machine and having two relatively rotatable parts capable of rotation about two mutually perpendicular axes. The device additionally includes a stylus assembly having a relatively stiff hollow stylus carrier, and a relatively flexible hollow stylus. An optical transducer system is provided within the stylus assembly and comprises a fixed light source which directs a beam of light towards a stylus tip, and a retro-reflective component at the tip which reflects the beam back to a fixed detector. The arrangement is such that lateral displacement of the stylus tip when the tip is in contact with a surface can be measured directly.