Lepton Series – LWIR Micro Thermal Camera Module

Radiometric Lepton modules output calibrated temperature values for each pixel, meaning they can measure actual object temperatures (within a certain range and accuracy). These modules (e.g. Lepton 2.5 and Lepton 3.1R) include an internal shutter and calibration data to provide real-time temperature readings across the scene. Non-radiometric versions (e.g. Lepton 3.5 and Lepton UW) produce a thermal image where pixel intensities correlate to relative heat, but are not absolutely calibrated – they’re useful for seeing heat patterns, but you would need an external reference or calibration if precise temperature measurements are required.

The Lepton series offers two core resolution configurations: 80×60 pixels (sometimes called Lepton 2.x) and 160×120 pixels (Lepton 3.x models). The 160×120 resolution modules provide a much finer thermal image with four times the number of pixels, allowing you to discern smaller details and cover a larger area with adequate resolution. The 80×60 modules, while lower in detail, are extremely cost-effective and sufficient for basic thermal detection tasks like presence sensing or spotting larger hot/cold spots. Both types have similar thermal sensitivity, but the higher resolution sensors, combined with their smaller pixel pitch (12 µm vs 17 µm on the 80×60), deliver a sharper and more detailed thermal picture when you need it.

Lepton modules come with a range of factory-configured lens FOV options to suit different applications. 50° FOV is a relatively narrow lens (standard on some 80×60 units like Lepton 2.5), focusing on a smaller area which can be useful for targeting distant objects or specific equipment. 57° FOV is a medium-wide view (common on Lepton 3.5) providing a balance between coverage and detail. 95° FOV is a wide-angle lens (as on Lepton 3.1R) ideal for covering larger areas or capturing more of a scene at once – for example, in security cameras or occupancy sensors to monitor an entire room. The widest option is 160° FOV on the Lepton UW, which is an ultra-wide fisheye-like lens capturing an extremely broad scene (such as an entire 180° hemisphere) – great for maximum coverage, though with significant distortion and lower effective resolution per area. In summary, a smaller FOV number (narrow lens) sees a tighter, more distant view with greater detail on a specific target, while a larger FOV (wide lens) sees a broader area which is useful for general monitoring or when you need to cover as much of the environment as possible.

Integrating a Lepton camera module is straightforward. The module mates via a standard 32-pin board-to-board connector (compatible with a Molex® 32-pin socket), and communicates using SPI for video data and a small I²C-like bus (CCI) for control commands. In practice, you supply power (the Lepton requires a few low-voltage rails, e.g. 2.8 V and 1.2 V) and connect the SPI lines to your microcontroller or processor to receive the live thermal video stream. The I²C connection is used to send commands or query status (for example, to perform calibrations or change settings). For development and prototyping, many engineers use a Lepton Breakout Board or similar adapter, which routes the Lepton’s pins to more accessible connections (and often includes power regulators) – this allows quick testing of the module on platforms like Raspberry Pi, Arduino, or PC interfaces before designing it into a custom PCB.

Yes – the Lepton is designed to be very power-efficient, which is one of the reasons it’s popular for mobile and handheld applications. In normal operation it typically draws around 150 mW of power or less, which is quite low for a thermal imager. In standby or low-power modes, it can sip as little as 4–5 mW (essentially negligible, allowing you to conserve energy when not actively capturing images). When the module performs an internal calibration (which involves a mechanical shutter, on radiometric versions), there is a brief power surge of up to ~650 mW, but this lasts only about 0.5 seconds and only occurs occasionally (you can control the frequency of these calibrations). Overall, the Lepton’s minimal power draw means it can run for long periods on a small battery – making it ideal for battery-operated IoT sensors, drones, wearable thermal cameras, and other portable uses.

The Lepton modules can detect a broad range of scene temperatures, though the exact range and accuracy depend on the model and whether it’s radiometric. For radiometric Leptons (like 2.5 and 3.1R), the typical calibrated temperature range in High Gain mode covers approximately -10 °C to +140 °C. This means these cameras accurately measure temperatures from about below freezing up to around the boiling point of water, which covers most normal environments and human/animal temperature ranges. They also have a Low Gain mode (automatically used when looking at hotter scenes) extending the measurable range up to around 450 °C – useful for viewing very hot objects like fires or machinery, albeit at a lower sensitivity/accuracy. Non-radiometric Leptons (3.5, UW) also detect heat far into these ranges (you will see very hot or very cold objects in the image), but since they don’t output absolute temperature values, you’d just interpret the relative intensities. It’s also worth noting the module’s operating temperature (the ambient temperature the camera itself can function in) is typically between about -10 °C and +80 °C. So, in summary, Lepton can handle and measure everyday temperature scenes easily, and even extreme heat up to a few hundred degrees Celsius in a limited way – which is impressive given its tiny size.