Linear Infrared Sensor Array With Extra Super-Sensitive Pixel for Spectroscopy Applications

Posted  by GoPhotonics

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Pyreos, a passive infrared sensor developer and manufacturer, has introduced a new 128+1 Linear Infrared Sensor Array. The sensor array comes with an extra, super-sensitive pixel that can be used in battery-powered spectrometers, bringing the laboratory out into the field in a whole range of industries, from food and drink to oil and gas. It offers a range of 128, 255 and 510 pixel passive pyroelectric linear mid-infrared sensor arrays for gas and liquid spectroscopy applications.

Pyreos arrays are known to be very sensitive, robust, highly integrated and can be used without cooling the devices. Pyreos has developed a unique thin film process that grows a sub-micron PZT layer on a semiconductor substrate. The benefits of this technology include a wide spectral range of 2-20 µm, exceptionally high responsivity (> 107 V/W at 500 K / 10 Hz) and long-term stability of the sensor. Most applications of the sensors are in the mid infrared “fingerprint” zone, which is best for identifying and measuring substances.

The arrays come in a compact 32 x 23 mm, 16-pin package and include Linear Variable Filters (LVFs). A LVF allows each pixel to see a specific part of the overall spectral range of the LVF (2.5-5.0 µm or 5.5-11.0 µm).  As a result, no moving parts such as grating devices or mirrors are needed. The package also includes a CMOS readout IC that uses low noise current amplifiers to pre-amplify the multiplexed analog output of the sensor arrays. The extra +1 sensor pixel that has been added is much larger than the pixels used in the rest of the array and has a 10-50x higher SNR depending on the implementation.

By applying an appropriate optical filter, the extra pixel can be used to “zoom in” on specific infrared wavelengths within the LVF spectral range with a much higher sensitivity. This allows lower concentrations of a key substance to be detected while the Line Array measures the broader spectrum. The extra pixel can also be used to look at wavelengths outside the spectrum being scanned by the LVF. While a third application involves using the extra pixel as reference channel that allows on-the-fly compensation for changing measurement conditions. In such a scenario, the frequency of background measurement can be reduced, which means a simplified and quicker measurement process.

Applications of the innovative 128+1 Linear Infrared Sensor Array include the analysis of gas, oil and foodstuffs (for food safety, and standards and payment applications). The 128+1 array is also in use in analysers built by several multinational companies worldwide. In foodstuffs, the array is used to detect and measure 15 or more common adulterants, and to detect unidentified additives. This allows customers to detect adulteration quickly to reduce food wastage. Testing can be done in the field using a portable, robust, battery powered device or in-line. The array is also used in oil condition monitoring. The sensor can detect sulphur levels, total acid and base numbers, oxidation, nitration and additive depletion allowing engine users to monitor engine and lubricant performance in real time in very hot environments.

Pyreos is currently offering several Line Array evaluation kits for both ATR and transmission spectroscopy, including an ATR kit that features the new 128+1 array.
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