Abstract:
A THz radiation probe for examining an object, the probe comprising a first portion configured to be inserted into an opening of said object in a first direction, said probe further comprising at least one THz emitter, directing means for directing THz radiation emitted from said emitter to said object via an aperture located at said first portion and subsequently from said object to at least one THz detector and, means for scanning said emitted THz radiation across said object in a scan direction, said scan direction having a component in said first direction.
Abstract:
Imaging techniques of pharmaceutical preparations such as tablets are disclosed. The techniques combine the measurement of reflected/transmitted terahertz radiation originating from within the tablet and data analysis localised in frequency and time in order to enable a three dimensional image indicating composition to be obtained.
Abstract:
An emitter for emitting radiation in a first range of frequencies comprising: a photoconductive material (11); and first and second contact elements (12, 13, 14) separated by a photoconducting gap provided by said photoconducting material (11), for applying a bias across said photoconducting gap, wherein at least one of said first and second contact elements (12, 13, 14) comprises a resistive element (14) for restricting current flow between said first and second contact elements in a second range of frequencies lower than the first range of frequencies.
Abstract:
The present invention provides a method of analysing an object (29) (for example a wive or a steut), comprising the steps of: (a) irradiating the object with a Terahertz pulse of electromagnetic radiation, such that a portion of the irradiating radiation couples to the object as a surface wave; (b) detecting radiation reflected and/or scattered from the object to obtain a time domain waveform; (c) extracting the parts of the radiation detected in step (b) relating to the surface wave on the object and (d) analysing the radiation identified in step (c) in order to derive information relating to a physical characteristic (for example the thickness of a coating) of the object.
Abstract:
A THz investigative system comprising a focussing member, said system being configured to transmit THz radiation through said focussing member, said focussing member having a focussing surface through which radiation is transmitted, said focussing surface being ellipsoidal.
Abstract:
An emission system, particularly a terahertz emission system comprising an emitter comprising a photoconductive material and first and second electrodes; an excitation device for applying a pulsed radiation signal to the emitter at a pulse repetition frequency; and a biasing means configured to apply an alternating bias voltage signal to the first and second electrodes at a frequency synchronised with the pulse repetition frequency. Applying an AC bias to the emitter, such that the frequency is synchronised with the irradiation frequency, preferably at half the frequency of the irradiation frequency of the excitation laser, serves to reverse the effects of space charge polarisation. The present invention does not prevent space charge polarisation occurring, but utilises it advantageously. That is, when the sign of the applied field for the next laser pulse is reversed, the space charge polarisation that has built up then acts to enhance the electric field between the electrodes while reducing the field directly adjacent to the electrodes.
Abstract:
A method of imaging a sample, the method comprising: (a) irradiating a sample with a pulse of electromagnetic radiation, said pulse having a plurality of frequencies in the range from 25 GHz to 100 THz; (b) determining a first parameter related to the amplitude of the radiation, which is either reflected from and/or transmitted by the sample, in the time domain; (c) calculating the value of the first parameter at a first time value relative to the value of the first parameter at a second time value which coincides with a physical feature of the dataset of the first parameter with respect to time; and (d) generating an image by plotting the value calculated in step (c) for different points of the sample.
Abstract:
A probe for examining a sample (5), the probe comprising an emitter (1) for emitting radiation, a detector (1) for detecting radiation and a dielectric member (3) configured to direct radiation from the emitter (1) to the sample (5) and to direct radiation reflected by the sample (5) to the detector (1), wherein in use, the dielectric member (3) occupies at least half of the radiation path length from the emitter (1) to the sample (5) to the detector (1).
Abstract:
A reflectometer for allowing a test of a device, the reflectometer comprising: a source of pulsed radiation; a first photoconductive element configured to output a pulse in response to irradiation from said pulsed source; a second photoconductive element configured to receive a pulse; a transmission line arrangement configured to direct the pulse from the first photoconductive element to the device under test and to direct the pulse reflected from the device under test to the second photoconductive element; and a termination resistance provided for said transmission line configured to match the impedance of the transmission line.
Abstract:
A reflectometer for allowing a test of a device, the reflectometer comprising: a source of pulsed radiation; a first photoconductive element configured to output a pulse in response to irradiation from said pulsed source; a second photoconductive element configured to receive a pulse; a transmission line arrangement configured to direct the pulse from the first photoconductive element to the device under test and to direct the pulse reflected from the device under test to the second photoconductive element; and a termination resistance provided for said transmission line configured to match the impedance of the transmission line.