The first article (January 2003) of this series dismissed five common myths about thermal imagers (TIs). These myths were:
Because TIs arise from a new and somewhat complicated technology, there are a number of misconceptions regarding what TIs can and cannot do. The first five addressed in the previous article in this series are the most common, and potentially place firefighters at the greatest risk. This article continues with more common myths and explains the reality.
Myth #6-Microbolometers are New Technology
Photo courtesy of Bullard
Figure 1: BST sensor engine with chopper wheel.
Two basic thermal imaging technologies are available today in the fire service, based on three different sensor materials. Generically, the technologies are known as ferroelectric and microbolometer. The two terms describe how the infrared detector receives thermal energy and then converts it into electrical signals to be processed. The detector, often called a sensor or focal plane array (FPA), is the key portion of the technology that allows TIs to detect heat.
The ferroelectric technology in the fire service today is often referred to as BST. BST stands for barium strontium titanate, the material that coats the sensor. Because all ferroelectric TIs sold in the fire service today have a BST sensor, the two terms are often used interchangeably.
Photo courtesy of Bullard
Figure 2: Vanadium oxide microbolometer sensor and engine.
Microbolometers have not followed the same pattern. There are currently two microbolometer sensor materials available to the fire service: vanadium oxide and amorphous silicon. The fire market considers vanadium oxide as the standard "microbolometer," while usually identifying amorphous silicon by name. The core technology behind both materials is similar; the primary difference is the sensor material itself.
All of the confusion about terminology has created an interesting myth. A number of people believe that microbolometers are new technologies.
Under the guidance of the US Department of Defense, Honeywell patented ferroelectric (BST) and microbolometer infrared detectors in the early 1980s, with about 18 months separating the two discoveries. Both technologies were highly advanced at the time and were classified by the US Military. Raytheon, Boeing and Lockheed-Martin (which sold its infrared business to British Aerospace or BAE) all licensed the technology from Honeywell and manufactured infrared detectors for military applications. After the 1991 Gulf War, these technologies were declassified, and preparations for introducing these sensors to the fire service ensued.
For a number of technical reasons, BST was the easier technology to adapt for the fire service. The BST sensor easily gained acceptance in the fire service because it dramatically outperformed earlier TI technologies, and it started to make major inroads around 1997.
Microbolometers (specifically those based on vanadium oxide or VOx) were delayed entering the fire service because they had larger technological hurdles to overcome. These devices made initial entry into the fire service in 1999. Amorphous silicon (or aSi) is the "newest" microbolometer technology, introduced in 2001 to the fire service.
This short history lesson shows that all of the confusion about the "newness" of each technology relates to when it entered the fire service market. Regardless of the entry time, however, the fact is that firefighters are using technology developed during Ronald Reagan's presidency.
Rather than worry about the newest technology, fire departments should concern themselves with selecting the TIs that will best meet their operational needs. They should also ensure that the chosen TI is easy to use, durable and offers excellent training and service.
Myth #7-Newer is Better