Rank Taylor Hobson

Red Sensors Ltd

Guidance IP Limited

Ian K Buehring

Daniel Ian Mansfield

Paul James Scott

John D Garratt

Jennifer Harding

David Mark Barnett

Ian Bell

The present invention provides an improved lidar apparatus () that can scan a surrounding volume without requiring the rotation or other movement of any component other than a scanning mirror (). The apparatus () comprises: a receiving lens () having an optical axis; the scanning mirror () that is angled to the optical axis of the receiving lens () and controlled to rotate about the optical axis of the receiving lens; at least one stationary laser source () that is positioned to emit light along an associated emission beam path () to be reflected by the scanning mirror () along an associated scanning beam path (); and at least one detector (), associated with a laser source () and positioned to receive light from said laser source () that is reflected by external objects and returned through the receiving lens () via the scanning mirror (). The apparatus () is characterised in that the emission beam path () is located at an angle to the optical axis of the receiving lens (). Embodiment of the invention comprise a plurality of laser sources () such that the apparatus can scan a 3D volume surrounding the apparatus () whilst holding each source stationary. The present invention also provides an improved method of lidar scanning that utilises any apparatus () according to the present invention.

Lidar apparatus and method

A method of lidar scanning over a rotational range provides a dense scanning pattern over the entire rotational range without the need for complex control of components. The method comprises rotating an angled scanning mirror at a first angular velocity about an axis of rotation; rotating a first diffractive or refractive optical element at a second angular velocity about the axis of rotation; controlling a stationary laser source to emit light along an emission beam path that passes through the first diffractive optical element before being incident upon the scanning mirror in order to reflect said light onto a scanning beam path; and detecting light reflected from external objects present in the scanning beam path.

Method of lidar scanning

A position reference sensor for a marine vessel comprises an optical assembly including a pulsed laser device for emitting laser light, a lens arrangement comprising a lenticular lens for producing a vertically fanned beam () of the laser light emitted by the pulsed laser device and a photodiode () comprising a plurality of photodetectors Rx, Ry, Rz for detecting laser light () that has been emitted by the pulsed laser device and reflected by a retro-reflective target () towards the photodiode (). The level of reflected laser light incident upon each photodetector is individually detectable and the position reference sensor further comprises an actuator for varying the inclination of the optical assembly. The actuator is automatically controllable based on the level of reflected laser light incident upon each photodetector Rx, Ry, Rz. A position reference sensor for a marine vessel comprises an optical assembly including a pulsed laser device for emitting laser light, a lens arrangement comprising a lenticular lens for producing a vertically fanned beam () of the laser light emitted by the pulsed laser device and a photodiode () comprising a plurality of photodetectors Rx, Ry, Rz for detecting laser light () that has been emitted by the pulsed laser device and reflected by a retro-reflective target () towards the photodiode (). The level of reflected laser light incident upon each photodetector is individually detectable and the position reference sensor further comprises an actuator for varying the inclination of the optical assembly. The actuator is automatically controllable based on the level of reflected laser light incident upon each photodetector Rx, Ry, Rz.

Position reference sensor

Probe measurement apparatus using a curved grating displacement

Apparatus for measuring surface roughness utilizes diffraction patterns derived from the surface under test. The energies in the different orders are detected and processed utilizing various different algorithms dependent upon a number of factors such as the number of orders in the diffraction pattern and asymmetry in the diffraction pattern. Various filter functions both for the diffraction pattern itself and for values of surface roughness after measurement are disclosed. One algorithm for measuring surface roughness involves comparison of values representing the energy orders with reference values, preferably reference values obtained by an interpolation operation between one set of reference values representative of a diffraction pattern from a symmetrical surface and another set representative of a diffraction pattern from an asymmetrical surface.

Apparatus and method using optical diffraction to measure surface

A metrological apparatus for measuring form and texture of a surface employs an inductive transducer producing an AC gauge signal, and a tracking AC analogue to digital converter. In order to avoid errors in the output signal at a relatively high speed of traverse of the surface due to a non-flat frequency response of the converter, the output signal is processed by a digital filter to provide a combined frequency response which is flat over a desired range. In order to avoid errors in the output signal due to non-linearity of the transducer, a square or cubic correction is applied to the signal. A method calibrating the apparatus to obtain coefficients for the square and cube terms in the correction process is also described.

Metrological apparatus and calibration method therefor

An interpolator, particularly for use with an optical grating for detecting position in a metrological apparatus, receives input signals in quadrature. One of the input signals is squared and the two signals are multiplied together to provide further signals in quadrature at twice the frequency of the input signals. One of the further signals is also squared and the further signals are multiplied together to provide output signals at four times the frequency of the input signals. Filtering is provided to remove DC components, such as due to drift. In the illustrated metrological apparatus, the zero crossing points of the output signals are detected to effect sampling, with high resolution, of a surface sensor output. Interpolation noise occurs at a high frequency and is removed by low pass filtering of the sample signal from the surface sensor.

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Leicester, United Kingdom

Ian K Buehring