New optoelectronic devices for the Mid-Infrared spectral range open completely new possibilities for portable sensors creation. Using Mid-infrared LED-PD optopairs allows developing an instrument that is smaller, less expensive and versatile.

Water-in-oil measurement

Water measurement in crude oil and petroleum products is an actual task for the petrochemical industry. The regular control of water concentration in oil well allows field operators to judge about the well performance and regulate the oil extraction process. In time water measurement in petroleum products helps to avoid costly breakdowns with loss of revenue. We offer our mid-infrared LED-Photodiode (PD) optopairs for development of water meters based on the optical absorption principle.

Water in oil detection with mid-infrared LEDs and PDs
Water and oil have strong absorption bands in mid-infrared spectral range 1.6 – 2.4 um: water has the main absorption band at 1800-1950 nm, oil – at ~1650-1850 nm.
For the analysis of water-oil emulsions we recommend using three-channel optical scheme that can provide compensation of the ambient effects, as well as scattering at water-oil drops’ interfaces: one LED – Lms16LED or Lms17LED – to determine oil absorption, second LED – Lms19LED – to determine water absorption and a third reference LED – Lms22LED – helps to consider non-water and non-oil influences on the emission propagation. Lms24PD series photodiode is optimal for detection signals from these three LEDs.
Spectra of LEDs and a PD for water in oil detection:

Using mid-infrared LED-PD based solutions provides certain advantages for this sort of application:

✔ Low power consumption (<1 mW)
✔ Short response time (10‒50 ns)
✔ Possibility to achieve modulation ranges of up to 100 MHz
✔ Operation temperatures up to +150°C
✔ Possibility to arrange a compact design of an optical cell thanks to compact size of the LED chip – 0.35 × 0.35 mm
✔ No need of using additional optical filters – LED emission band width is comparable to absorption band widths of water and oil
✔ Lifetime of 80 000 hours

LED-PD based Evaluation systems for water in oil measurement
NEW LA-1t LED Analyser a device oriented for the initial experiments with different liquid (and other) substances, enables defining the absorption properties of the analyzed sample in the spectral range 1.3 – 2.3 µm.
LA-1t’s optical module includes:
- 8-element LED array with peak emission wavelengths about 1.3, 1.4, 1.6, 1.7, 1.9, 2.1, 2.2 and 2.3 µm;
- Wideband photodiode with a cut-off wavelength about 2.4 µm and 2 mm sensitive area diameter;
- ZigBee/Bluetooth wireless data transmission module for fast data transfer to a data control center;
- Battery power supply for autonomous operation.

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