Abstract: 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.

Abstract: 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.

Abstract: 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 (18) of the laser light emitted by the pulsed laser device and a photodiode (32) comprising a plurality of photodetectors Rx, Ry, Rz for detecting laser light (28) that has been emitted by the pulsed laser device and reflected by a retro-reflective target (22) towards the photodiode (32). 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.

Abstract: 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 (18) of the laser light emitted by the pulsed laser device and a photodiode (32) comprising a plurality of photodetectors Rx, Ry, Rz for detecting laser light (28) that has been emitted by the pulsed laser device and reflected by a retro-reflective target (22) towards the photodiode (32). 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.

Abstract: 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.