Abstract: A leak detector (1) adapted to detect a leak (40) of a first material by detecting a change in a physical/chemical property of a second material. The leak detector includes a quantum cascade laser (5) and a detector (35).

Abstract: A hyperspectral sensor or imager comprising a laser for illuminating a scene and a detector for detecting light emitted by the laser and transmitted through the scene, wherein the laser is a chirped laser arranged to output multiple pulses having different wavelength ranges, the multiple pulses being used to form an extended continuous spectrum for illuminating the scene.

Abstract: An optical arrangement comprising a multi-mode fiber (16) for carrying single mode laser light (12); a randomizer (18) for randomizing spatial modes supported by the fiber and means for averaging, out the randomized spatial modes to recover the single spatial mode.

Abstract: A portal or gateway that includes a detector comprising a chirped laser; an open optical sample cell and a detector for detecting light from the chirped laser that has passed through the cell. The chirped laser may be a quantum cascade laser.

Abstract: A portal or gateway that includes a detector comprising a chirped laser; an open optical sample cell and a detector for detecting light from the chirped laser that has passed through the cell. The chirped laser may be a quantum cascade laser.

Abstract: An optical arrangement comprising a multi-mode fiber (16) for carrying single mode laser light (12); a randomizer (18) for randomizing spatial modes supported by the fiber and means for averaging, out the randomized spatial modes to recover the single spatial mode.

Abstract: A leak detector (1) adapted to detect a leak (40) of a first material by detecting a change in a physical/chemical property of a second material. The leak detector includes a quantum cascade laser (5) and a detector (35).

Abstract: A method apparatus for sensing gases using a semiconductor diode laser spectrometer, the method comprising: introducing a sample gas into a non-resonant optical cell (17); applying a step function electrical pulse (19) to a semiconductor diode laser (20) to cause the laser (20) to output a continuous wavelength chirp for injecting (16a) into the optical cell (17); injecting (16a) the wavelength chirp into the optical cell (17); using the wavelength variation provided by the wavelength chirp as a wavelength scan, and detecting (23) light emitted from the cell (17), wherein a chirp rate is selected to substantially prevent light interference occurring in the optical cell (17).