PYROMID® Multi Channel Detectors

LRM detectors by InfraTec, a series of miniaturised multi channel detectors, offer an extremely wide field of view (FOV) in combination with a compact design and attractive pricing. Their most obvious hallmark is a robust central window in the cap, e.g. made of silicon. It offers reliable protection against environmental influences such as penetrating moisture. Optionally soldered to the housing this central window enables complete hermetic sealing.

The channel filters are placed inside the detectors. Shielded from mechanical stress as well as from other strains from harsh environments they are located close to the pyroelectric elements. The reduced distance and the central window integrated into the detector caps are two of the factors that ensure a wide FOV. At the same time, all elements are placed close together inside the detectors. This allows more radiation to reach the pyroelectric element and therefore a higher signal. In addition, since the optical crosstalk of the individual channels is suppressed very effectively, the entire detector series proves to be extremely powerful. The compact, miniaturised construction allows for more analysis channels with unchanged package size. Or, the same number of channels can be integrated into significantly smaller packages.

The LRM-292 pyroelectric detector from InfraTec is, next to the LRM-202, the world‘s smallest multi-channel detector with integrated operational amplifier and thermal compensation. With a diameter of only 4.7 mm, the LRM-292 is predestined for measuring low gas concentrations at small measurement volumes. Fast gas changes, low gas concentrations, and short gas exchange times are not a challenge for the pyroelectric detector in a compact TO46 housing.

The LRM-292 and LRM-202 owe their compact design to the tried-and-tested stacked construction method. Its unique design means that both detectors have a field of view (FOV) of 60°, exposing a very large proportion of the radiation to the pyroelectric elements. This generates high amplitudes of the output signal, which supports external signal amplification.

* (500 K, 10 Hz, 1 Hz, 25 °C, without window) / 10 E + 8 cm Hz1/2 / W

Beam splitter detectors are perfectly suited for measurement tasks that demand accurate and stable measurement results over the long term. These multi channel detectors are equipped with only a single aperture. They contain an array of micro mirror surfaces working as an internal beam splitter. Due to the detector’s single aperture opening, major parts of the incoming radiation impinges reflectively to the pyroelectric crystal. This allows for very precise NDIR gas analysis particularly in gas detection technology. To solve such measurement tasks, a gas cell with an effective diameter of just 2.5 mm is sufficient. Apart from an accelerated exchange of gas, this results in very low dead volumes of the measuring system. Measurement devices equipped with the detector can be correspondingly smaller. The permanently stable signal ratio between the individual channels ensures a high degree of measurement accuracy.

The beam splitters used by InfraTec are solely reflection beam splitters and consist of highly reflective gold plated microstructures. The division of the beam into two or four spectral channels is done only within the detector.

 The radiation entering through the aperture opening of the detector is split into several radiation beams of equal intensity but in different, predefined directions within the detector based on the architecture of the innovative microstructure inside. Each of the beams impinges on a corresponding pyroelectric sensor element with an upstream optical filter.

Mechanical expansions in the optical system of the measurement device, ageing effects or any possible contamination of these detectors are already accounted for before the beam is split and thus affect all channels equally. This minimises differences between the measurement channels and the required beam diameter. The microstructures vary according to the detector type. In quad channel detectors these resemble four-sided micro-pyramids, whereas in dual channel detectors these are V-shaped grooves.

• Multi channel detectors with a single aperture
• High degree of measurement accuracy due to a permanently stable signal ratio between the individual channels
• Simple constructive solutions allow exact same reflected intensities of the individual radiation beams
• Very low dead volumes of the measurement systems
• Small gas cells enable easy integration into measurement devices

* (500 K, 10 Hz, 1 Hz, 25 °C, without window) / 10 E + 8 cm Hz1/2 / W