Abstract: An infrared detection system comprises the following elements. A laser source provides radiation for illuminating a target (5). This radiation is tuned to at least one wavelength in the fingerprint region of the infrared spectrum. A detector (32) detects radiation backscattered from the target (5). An analyser determines from at least the presence or absence of detected signal in said at least one wavelength whether a predetermined volatile compound is present. An associated detection method is also provided. In embodiments, the laser source is tunable over a plurality of wavelengths, and the detector comprises a hyperspectral imaging system. The laser source may be an optical parametric device has a laser gain medium for generating a pump beam in a pump laser cavity, a pump laser source and a nonlinear medium comprising a ZnGeP2 (ZGP) crystal.

Abstract: The invention relates to a method and apparatus for reducing speckle noise in a system comprising a sensor for detecting electro-magnetic radiation backscattered from a target, comprising: illuminating the target with a first illuminating beam having a first optical path; illuminating the target with a second illuminating beam having a second optical path different to the first optical path; capturing at the sensor first and second backscattered radiation components associated with respectively the first and second illuminating beams, each of the backscattered radiation components comprising a speckle pattern; and taking a time-averaged measurement of the intensities of the first and second backscattered radiation components; wherein the capturing step is carried out within an integration time ? of the sensor, such that the time-averaged intensity measurement results in a decrease in speckle noise present in a signal representing the backscattered radiation.

Abstract: An infrared detection system comprises the following elements. A laser source provides radiation for illuminating a target (5). This radiation is tuned to at least one wavelength in the fingerprint region of the infrared spectrum. A detector (32) detects radiation backscattered from the target (5). An analyzer determines from at least the presence or absence of detected signal in said at least one wavelength whether a predetermined volatile compound is present. An associated detection method is also provided. In embodiments, the laser source is tunable over a plurality of wavelengths, and the detector comprises a hyperspectral imaging system. The laser source may be an optical parametric device has a laser gain medium for generating a pump beam in a pump laser cavity, a pump laser source and a nonlinear medium comprising a ZnGeP2 (ZGP) crystal.

Abstract: A method is provided of obtaining a vapor phase spectrum of a compound. The method comprises providing an isolated condensed phase sample of the compound, vaporizing the sample and supplying the vapor to an absorption cell of a spectrometer. A rate at which vapor enters the absorption cell is determined and a steady state concentration of vapor in the absorption cell is established. The spectrum of the vapor is then measured.

Abstract: A tunable coherent radiation source comprises a pump laser which outputs a pump beam and a non-linear optical medium having a tuning pattern to provide tuning across a wavelength range. A translation system is arranged such that the pump beam is translated across the tuning pattern. The scanning pattern is formed such that translation of the pump beam across the tuning pattern provides one or more discontinuities in tuning across the wavelength range. A spectroscopic system and a hyperspectral imaging system comprising such a tunable coherent radiation source are described, as is a non-linear optical medium adapted for use in such a source. A method of providing coherent radiation tuned over a wavelength range is also described.