Lab Insights

This site is a platform for photonics technology concepts, demos and know-how. A way to connect with people and technologies in the AIPT labs. Some ideas are not published but could be useful. Some are published, some just need a bit of nurturing. If you see something that might work for you, then contact us, we are always looking to collaborate and move beyond the lab.

Non-contact surface moisture monitor

FUNCTION: A set of LEDS illuminates a surface and monitors the reflectivity. Does not use probes which damage the surface.

This simple demonstrator is based on an Arduino shown in the top photo. Water placed onto a paper towel slowly spreads across the sensor’s field of view. The graph shows the output signal showing the change in reflectivity as the amount of water in the surface changes.

Application Areas:
•   Construction – for determining damp levels
•   Agriculture – crop and soil moisture levels.
•   Humidity measurements possible

✉ Dr David Benton

Non-contact surface moisture monitor

Non-contact surface moisture monitor and output trace

Image 1: Non-contact surface moisture monitor (top) and output trace (bottom)

Vibration Sensitive Surface

FUNCTION: A low cost vibration sensitive surface.

A surface inset with optical fibres acting as an interferometer can detect small disturbances. Because the fibres are inset the sensitivity extends across the whole surface. The scale is currently that of an A4 piece of paper with simple and low cost electronics. Can detect large changes such as impact or intrusion, or small scale changes such as breathing.
The photo shows the surface placed on the top of a box which contains the fibres, laser, detector and electronics, with the signal being displayed on the laptop as the hand is placed on the surface.

Application Areas:
•   Intrusion detection,
•   Pressure change sensing,
•   Patient monitoring (movement, breathing)

✉ Dr David Benton

Laser Detection Technology

FUNCTION: Detects laser radiation even against bright backgrounds.

This technology detects lasers – specifically. It discriminates between lasers and say LEDs or natural sources. This enables enhanced sensitivity in detecting lasers against bright backgrounds. It detects coherence — a fundamental property of lasers – using a compact, low cost interferometer.

Application Areas:
•   Defence where detection of lasers is crucial
•   Sensing applications where background light is a problem
•   Free space optical communications

✉ Dr David Benton

Published: D. M. Benton, “Low-cost detection of lasers,” Opt. Eng., vol. 56, no. 11, p. 1, 2017,
doi: 10.1117/1.OE.56.11.114104


Image 3: Schematic representation (top) of the Laser Detection Device (bottom).

Atmospheric Turbulence Emulator

Image 4: Atmospheric Turbulence Emulator and its output trace

FUNCTION: Emulates the degrading effects of atmospheric turbulence on an optical beam on the lab bench.

Uses a micromirror array – the Texas Instruments DMD (shown in photo) to create diffracted wavefronts that are distorted by controlled amounts, emulating controllable amounts of atmospheric scintillation.

Application Areas:
•   Testing of free space optical communication systems
•   Testing of laser sensing systems

✉ Dr David Benton

Published in Engineering Research Express

Emulating atmospheric turbulence effects on a micro -mirror array: assessing the DMD for use with free-space-to-fibre optical connections