Abstract: An apparatus and method for imaging a sample, the apparatus including a source for irradiating a sample with a beam of substantially continuous electromagnetic radiation having a frequency in the range 25 GHz to 100 THz; means for subdividing an area of the sample which is to be imaged into a two dimensional array of pixels; means for detecting radiation from each pixel wherein the detector is configured to detect a phase dependent quantity of the detected radiation which is measured relative to the radiation which irradiates the sample.

Abstract: A method of quantitatively analysing a sample, the method comprising: irradiating the sample with radiation having a plurality of frequencies in the range from 25 GHz to 100 THz; detecting radiation reflected from and/or transmitted by said sample to obtain a frequency domain waveform of said sample; identifying at least one section of interest of said frequency domain wave-form containing spectral features due to intermolecular or other non-intramolecular excitations; and obtaining a value related to the concentration of a component of the sample from the said section.

Abstract: A laser comprising: a substrate comprising a bulk region and a conducting layer; an active region (11) comprising a quantum cascade structure provided on a first surface of the substrate (12) such that said active region (11) is electrically connected to said conducting layer; first and second contacts (16, 17) being disposed on opposite sides of said active region (11); and an active region contact (31) provided to said active region (11) such that a potential may be applied between said active region contact (31) and said first and second contacts (16, 17) to cause said active region (11) to lase.

Abstract: A radiation source comprising a frequency conversion member (1) configured to emit a beam of emitted radiation (7) with at least one frequency in the range from 0.1 THz to 100 THz, in response to irradiation with an input beam (3) with a frequency different to that of the emitted radiation (7), the source being subjected to a magnetic field (9) which has a component parallel to that of the emitted beam of radiation (7). The radiation source may be optimised by using both the fluence of the input beam and the magnetic field or may comprise a magnetically doped frequency conversion member or also have means for applying an electric field.

Abstract: In an apparatus and method for imaging a sample: a) the sample to be imaged is irradiated with pulsed electro-magnetic radiation with a plurality of frequencies in the range from 50 GHz to 84 THz; b) an area of the sample is subdivided into a two dimensional array of pixels, and radiation from each pixel is detected over a plurality of frequencies; and c) an image is generated from the radiation detected in step (b) preferably using a frequency or a selection of frequencies from the plurality of frequencies in the pulsed electro-magnetic radiation. The method can be used as a medical imaging technique and can be used to image cancer tumours.

Abstract: An apparatus for investigating a sample, the apparatus comprising an emitter (1) for irradiating the sample (27) with a beam of emitted electromagnetic radiation; and a detector (49) for detecting the radiation reflected from the sample, wherein there is an optically non-linear member (15) which functions as both an active part of the emitter and an active part of the detector, said emitter and detector using the same part of the optically non-linear member (15). The electromagnetic radiation is primarily intended to be in the terahertz (THz) frequency range.

Abstract: A method and apparatus for imaging a sample, the method comprising the steps of: a) irradiating a sample to be imaged with a beam of pulsed electromagnetic radiation with a plurality of frequencies in the range from 25 GHz to 100 THz; b) detecting radiation which is both transmitted through and reflected from the sample; and c) generating an image of the sample from radiation detected in step (b). The method and apparatus can be used to generate a three-dimensional image of the sample and/or a compositional image of the sample.