PYROMID® Multi Channel Detectors

Miniaturised Detectors for Gas Analysis and Flame Detection

The PYROMID® brand stands for detectors with compact stack design, the LRM detector family, as well as multi channel detectors with internal beam splitters.

Features of PYROMID® multi channel detectors from InfraTec

  • Multi channel detectors with up to eight channels
  • Integrated beam splitter or micromechanical frame
  • Easy integration into measurement devices
  • For use in gas analysis and flame detection

How Does a Pyroelectric Detector Work?

Pyroelectric crystals have a rare asymmetry due to their single polar axis. This causes their polarisation to change with temperature. This so-called pyroelectric effect is used in sensor technology. For this, a thin pyroelectric crystal is coated perpendicular to the polar axis with electrodes. On the upper electrode of the crystal, an absorbing layer (black layer) is applied. When this layer interacts with infrared radiation, the pyroelectric layer heats up and surface charge arises. If the radiation is switched off, a charge of the opposite polarity originates. However, the charge is very low. Before the finite internal resistance of the crystal can equalise the charges, extremely low-noise and low leakage current field-effect transistors (JFET) or operational amplifier (OpAmp) convert the charges into a signal voltage. 

PYROMID® multi channel detectors from InfraTec

LRM Detectors

Miniaturised Multi Channel Detectors with Compact Stack Design

Cutting Edge Technology in Most Confined Spaces

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.

Innovative Modular Stack Design

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.

PYROMID® multi channel detectors from InfraTec
PYROMID® multi channel detectors from InfraTec

High-tech in the Smallest Space

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.

LRM-292 - Small Multi Channel Detector with Current Operation

In the LRM-292, two integrated operational amplifiers are connected as transimpedance amplifiers. The current mode produces higher output signals than the LRM-202 in voltage mode. This simplifies signal processing and provides an excellent signal-to-noise ratio even at frequencies above 10 Hz. Additionally, the LRM-292 has been designed to use only one supply voltage, thereby reducing the amount of circuitry required.

LRM Detectors at a Glance

  • Assortment of two, four and eight channel detectors
  • Operation in voltage mode or current mode
  • Extremely wide FOV provides powerful performance
  • TO46, TO39 and TO8 housings available
  • Robust central window for protection against penetrating moisture
  • Option for complete hermetic sealing
  • Available with thermal compensation

Model Range – LRM Detectors

Number of channels2244448
Element size (mm2)/channel1.2 × 0.81.2 × 0.81.4 × 1.41.4 × 1.42.0 × 2.02.0 × 2.01.4 × 1.4
Thermal compensationYesYesYesYesYesYesYes
Current/voltage modeVMCMVMCMCMCMCM

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

Compact Pyroelectric Detectors Based on Micro-machined Chip Carriers

Planar multi channel pyroelectric detectors from InfraTec

A miniaturized multi channel detector differs in many ways from a more conventional multi-channel detector. For example, it features special chip carriers. The influence of such elements on the performance of these special detectors is clearly illustrated in this technical article.

Beam Splitter Detectors

Precise and Stable Measurements for Long-term Applications

Unconventional Solution for Precise Measurements

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.

One of a Kind – Reflection Beam Splitter

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.

Advantages of Beam Splitter Detectors

  • 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
PYROMID® multi channel detectors from InfraTec
PYROMID® multi channel detectors from InfraTec

Model Range – Beam Splitter Detectors

Number of channels244
Element size (mm2)/channel2.2 × 1.32.2 × 1.32.2 × 1.3
Thermal compensationNoNoNo
Current/voltage modeVMVMCM

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

Get in contact with InfraTec sensor division

Would You Like to Know More?

It is not unusual for tasks to be associated with special requirements. Discuss your specific application needs with our experienced engineers, receive further technical information or learn more about our additional services.

Europe & Rest of World

InfraTec GmbH
Infrarotsensorik und Messtechnik
Gostritzer Str. 61 – 63
01217 DresdenGERMANY

Download Flyer - PYROMID® Multi Channel Detectors

Miniaturised Detectors for Gas Analysis and Flame Detection