Novel imaging device to be used with millimetre and/or sub-millimetre radiation

Description of the offer

The invention is a sub-millimetre wavelength imaging device and particularly but not exclusively an ambient temperature camera using either single or multiple heterodyne detectors. The terahertz electromagnetic spectrum extends over a range of frequencies where radio waves and optical waves merge and consequently the detection of terahertz radiation utilizes a mixture of optical and radio wave technology. As a result of the dimensions of the individual components required to image at terahertz frequencies, the cost of terahertz imaging systems has generally been prohibitive. However, terahertz frequencies have long been recognised as potentially extremely useful frequencies for imaging purposes as many materials which are opaque in the visible region of the spectrum become transparent to terahertz waves. In particular, imagers at terahertz frequencies are suitable for imaging the Earth's surface as most weather conditions such as fog are transparent to terahertz waves. This also makes a terahertz imager a potentially useful imaging device when flying a plane or driving a land vehicle in bad weather, for example.

The transparency of many materials to terahertz frequencies has also been identified as a useful tool for security purposes. Most notably clothing becomes transparent at these frequencies enabling hidden weapons worn under clothing to be seen clearly and for spotting people hidden in canvas sided trucks and lorries. Furthermore, In view of the fact that human bodies radiate at these frequencies, terahertz radiation has also been identified as a potentially powerful diagnostic tool for example in the early detection of skin cancers. Also, applications of terahertz imaging in the chemical and food industries have been identified, for example in the detection of one or more constituents each having different transmissive/reflective properties at these frequencies.

The specific invention is an imaging device capable of detecting low power passive terahertz radiation and of operating at ambient temperatures, in sub-millimetre (i.e. terahertz) and/or millimetre wavelength range. The imaging device is used with millimetre and/or sub-millimetre radiation comprising a pair of substrates, one of which is patterned on a surface with a patterning defining one radiation receiver. Each radiation detector comprises:
An antenna adapted to receive millimetre and/or sub-millimetre electromagnetic radiation.

A mixer channel coupled to said antenna and in communication with a via extending through a substrate for connection to a signal output, a mixer comprising filters being mounted in the mixer channel for extracting an intermediate frequency signal in dependence upon said radiation received by the antenna.

A waveguide structure coupled to said mixer and having a local oscillator signal input for connection to a local oscillator. The pair of substrates have patterning defining in combination a number of antennae with respective mixing channels and local oscillator waveguide structures. Also, one of the pair of substrates may be patterned on opposed surfaces and the imaging device may further comprise a third substrate patterned on one of its surfaces such that the three substrates co-operably define by means of their patterning two rows of antennae and respective mixing channels and local oscillator waveguide structures.

Innovations and advantages of the offer:

Suitable for the detection of passive millimetre and sub-millimetre electromagnetic radiation

• Compact size
• Portable
• Able to perform at room temperature

Domain of Application:

Immediate applications for the imaging device are envisaged in both airborne and land vehicles, in security systems, in the chemical and food industries and in medical diagnostics. However, the scope of applications is not limited to those identified above and because of the low power requirements of the imaging system it is particularly suited for example to imaging from space.

• Military electronics (excluding communications)
• Medical imaging
• Diagnostic test products and equipment