Night vision

Every skipper dreads being forced to a different anchorage at night when it’s difficult to see the surroundings. FLIR thermal imaging technology makes the job a lot easier.

AFLIR (Forward Looking Infrared) camera is particularly useful when navigating around a dark bay filled with moored craft.

The units began appearing on New Zealand recreational boats around 2006, but the technology dates to 1978 and was first geared to aviation systems. Today FLIR is the world’s largest producer of thermal cameras and is listed on the NASDAQ exchange with a market capital of over $5 billion.

HOW FLIR WORKS

FLIR cameras detect only infrared energy (not light) and, as a result, the lens of the unit uses a pricey rare metal called germanium because of its infrared conducting ability. The cameras cannot use a glass lens because glass is a barrier to infrared. Which is why FLIR units are usually mounted outside – on a vessel’s deck or superstructure – and not inside.

At the core of each camera is a device called a microbolometer. It detects infrared radiation with wavelengths of between 7.5 and 14μm. A microbolometer comprises an array of pixels that can be measured and processed to create an image.

Every object emits infrared energy, regardless of its temperature. Objects at well below freezing are still visible due to their infrared footprint, so even ice is easy to see. The difference between infrared and visible light is the wave length. Infrared has a much longer wave length.

But there is a correlation between the amount of infrared light and the actual temperature of an object. For this reason, the technology’s been used for

decades for non-contact temperature measurement. It’s useful for measuring the temperature of very hot products such as molten glass and steel.

For the most part, a FLIR image looks the same as one from a black and white video camera. But image detail is very clear and the unit will even detect debris in the water such as pieces of timber. This makes life easier for skippers as there is no requirement to ‘interpret’ data or patterns. What you see is what you get.

HOW FAR?

FLIR splits its range specification into two definitions – detection and identification. Detection is the first point – when you clearly see an object appear on your screen. Identification is when you clearly identify the target. For example, an image of a 50ft launch will be identified at a much greater distance than a small runabout or kayak.

The company publishes a specification table for all its cameras, so you can decide which model best suits your needs. Most recreational vessel units have a 320x240 microbolometer. These can detect a four-metre vessel at around 1.9km (1nm) – adequate for collision avoidance even at speed.

Like all technologies there are limitations and environmental factors will affect range. The height of the image relative to the sea is an important consideration, and the higher the camera is placed the better the image quality and range.

Ambient air temperature, too, has an impact. A greater differential between the surroundings and a warm object will translate to sensitivity. In general, cooler, dry nights deliver the best results.

DUAL-PAYLOAD

Harbours and rivers that near cities can be affected by the heat created from cars, asphalt and buildings. Issues may arise directly after dusk as all this heat translates to infrared energy. High levels can swamp the imager and greatly reduce the sensitivity and reduce the camera’s functionality.

But large cities also provide large amounts of light and a quality, low-light colour camera can work well. For this reason, FLIR introduced its dual-payload camera – a unit with both a FLIR and low-light function. The combination of the two technologies gives the skipper the best of both worlds.

The FLIR cameras are generally supplied with a 9-30Hz refresh rate. This refers to the update speed at which the screen gets information from the camera – 9Hz is nine times per second vs 30 times per second. Given that a FLIR unit points directly ahead looking at objects far away (rather than objects moving rapidly from side to side), the refresh rate doesn’t have a major relevance for recreational boaties.

The higher the camera is placed the better the image quality and range

THE M400

This is the premium camera within the M series and offers two significant benefits. The first is minimising the rolling and pitching of an image, as experienced in rough seas.

The M400 electronically stabilises the image – just like a gyro. Stabilisation – combined with the new communication interface – means that the M400 can now slew to cue and track from radar, AIS and chartplotter systems. The optional XR model has the added ability to lock on to any video-selected target on the screen – as set by the user – and track it.

NEW MODELS

Absolute Marine has just taken delivery of FLIR’S latest M100 and M200 low-cost cameras. These offer similar features to their predecessors, but are Ethernet-based and rely on a computer network to communicate and display the video image.

Later this year we expect delivery of the next generation of FLIR M-series cameras. These new models promise even better image quality and feature the new-generation FLIR cores. More significantly, they are all equipped with auto gyro-stabilisation.

In addition, all the dual payload models will upgrade from black and white daylight cameras to full colour. These new, lower cost units make it more affordable for a new generation of boaties to have FLIR as standard equipment and make boating safer at night.