Almost all of the Long Range thermal systems that are currently available on the professional market are equipped with cooled FPAs. Cooled and uncooled FPAs have their pros and cons. Click on tabs on the left to see the major factors that will help the End User make the right decision.
Cooled/Uncooled. Cooled FPAs exhibit higher sensitivity compared to uncooled counterparts. An operator could discern even slightest changes in temperatures and read out a precise thermal image with a cooled FPA. Despite this benefit cooled FPAs produce a massive amount of thermal energy (or heat) that must be dissipated by means of a cooler (e.g. a rotary Stirling cryogenic cooler). The required add-on makes the thermal system bulkier, more power-consuming, more expensive and heavier.
Performance of even the most sensitive FPA could be ruined by pairing it to poor quality optics. Overall sensitivity of a thermal imaging system is governed by two major factors: FPA sensitivity and objective lens f-number. In many cooled systems manufacturers go for high f-numbers to compensate for significant cost of cooled sensors. Increasing objective lens f-number totally jeopardises the whole idea of a sensitive long range thermal system. For example, pairing a 25mK-senstitive cooled FPA to a “slow” f/4.0 objective lens results in an unimpressive overall sensitivity of 25mK x 4 = 100mK, while sensitivities of 60mK can be easily achieved by using a high-resolution uncooled sensor and a “fast” f/1.0 objective lens with no excessive power consumption and retaining compact size and weight. As a result, more sophisticated and expensive cooled systems deliver real-life performance (detection/recognition/identification of objects) that is identical or lower than that of uncooled systems with fast objective lenses.
Any cooled thermal imaging system consumes significant amount of electric energy, incomparable to what uncooled systems need to operate. Oftentimes voltages that most cooled systems require (˜24VDC) cannot be instantly supplied by places these systems are installed onto, e.g. vehicles with 12VDC power outlets. Such systems lack convenience of use as they require specialized power sources or additional voltage converters. Ability to operate autonomously (on batteries) is vital in emergency situations like power outages or when external power source is not readily available.
The more intense heat an object emits, the more likely it can be detected from a distance by other thermal imaging devices. If a cooled thermal system is set up and running in a standalone (remote) location, it radiates significant amounts of thermal energy, enough to be detected and therefore pin-points the position of the unit and with it, of course, reveals the location of the entire crew. Uncooled systems are deprived of this drawback, generating 20 times less heat, these systems are almost 100% protected from an unwanted detection.
Majority of coolers for cooled FPAs need to be serviced every year with maintenance costs of up to 10% of the price of the whole system. In contrast, uncooled thermal detectors, and systems they are based on, are completely maintenance-free and therefore do not incur any additional costs associated with their servicing.