1. Core Definition and Fundamentals

Pixel pitch is the physical distance between the centers of two adjacent pixels on a thermal imaging sensor (microbolometer), measured in micrometers (μm). It is a fundamental parameter defining how closely packed the infrared sensing elements are on the focal plane array (FPA).

Critical Distinction

• Pixel pitch ≠ pixel size: pixel pitch refers to spacing, while pixel size is the physical dimension of the sensing element itself (often slightly smaller than the pitch).

• Pixel pitch × resolution = sensor diagonal: for a 320×240 sensor with 12μm pitch, the sensor size is approximately 3.84mm × 2.88mm.

2. How Pixel Pitch Impacts Performance

2.1 Spatial Resolution and IFOV

• Smaller pitch → higher pixel density for the same sensor size, improving spatial resolution and instantaneous field of view (IFOV)

• For identical focal length, a 12μm pitch collects approximately 1.42× more pixels per angle than 17μm, extending detection/recognition ranges

• IFOV formula: IFOV (mrad) = Pixel pitch (mm) / Focal length (mm) × 1000

2.2 Thermal Sensitivity (NETD)

• Larger pixels → greater surface area → more infrared radiation absorption → better signal-to-noise ratio (SNR) → lower NETD

• Trade-off: smaller pitches (≤12μm) require advanced readout circuits and often cryogenic cooling to maintain sensitivity, increasing power consumption and cost

2.3 Sensor Size and SWaP-C

• Smaller pitch → smaller sensor for the same resolution, enabling smaller and lighter lenses (critical given the cost of germanium optics used in thermal cameras)

• More compact modules — for example, FLIR Boson+ at 7.5g and under 4.9cm³

• Lower power consumption — starting at 500mW for advanced modules

2.4 Cost Considerations

• Smaller pitch → higher manufacturing complexity → higher cost per unit area

• Larger pitch (e.g., 35μm) → lower cost for applications prioritizing temperature monitoring over fine detail

3. Common Pixel Pitch Specifications and Applications

4. Thermal Camera Module Architecture

A typical thermal imaging camera module includes:

• Microbolometer FPA: the core sensor with defined pixel pitch (VOx is the most common uncooled technology)

• Optical system: germanium lens, optimized for long-wave infrared (8–14 μm)

• Readout Integrated Circuit (ROIC): converts bolometer resistance changes to digital signals

• Image Processing Unit (ISP): performs non-uniformity correction (NUC), image enhancement, and temperature calculation

• Calibration components: mechanical shutter for offset compensation, critical for radiometric accuracy

• Interface: USB, MIPI, CVBS, or GigE for data output

5. 12μm vs 17μm: The Core Trade-off

12μm Advantages

• 1.42× higher pixel density for the same focal length → extended detection ranges

• Smaller lenses (approximately 71% the size of the 17μm equivalent) → reduced weight and cost

• More compact modules — well suited to SWaP-constrained applications such as drones and wearables

17μm Advantages

• 2× larger pixel area → better sensitivity (NETD below 25mK achievable)

• Lower read noise → improved performance in low-contrast scenes

• More forgiving optics → wider depth of field, simpler lens design

Application Guidance

• Choose 12μm for: drone inspections, compact security devices, high-detail building diagnostics

• Choose 17μm for: long-range surveillance, firefighting (smoke penetration), low-light wildlife or perimeter observation

6. Selection Criteria for Thermal Camera Modules

Application Requirements

• Spatial detail vs. sensitivity trade-off (smaller pitch = better detail, larger pitch = better sensitivity)

• Detection range — calculate required IFOV based on target size and distance

• Temperature measurement accuracy — radiometric vs. non-radiometric

Environmental Constraints

• Size/weight limits (smaller pitch enables more compact designs)

• Power budget (smaller pitch may require more power for equivalent sensitivity)

• Operating temperature (typically -40°C to 80°C for industrial modules)

Cost Considerations

• Resolution vs. pitch balance: 384×288 with 12μm offers better value than 640×512 with 17μm for many applications

• Long-term TCO: smaller lenses reduce replacement costs for germanium optics

7. Emerging Trends

• Sub-10μm pixel pitches: 8–10μm sensors are now available for high-end applications, offering unprecedented detail in compact form factors.

• Wafer-level packaging (WLP): reduces module size and cost while improving reliability.

• Multi-spectral integration: combining thermal (12μm) with visible or SWIR sensors for enhanced situational awareness.

Final Recommendations

• For most commercial applications: 12μm pixel pitch with 384×288 resolution offers the best balance of performance, size, and cost.

• For cost-sensitive monitoring: 17–35μm with 256×192 resolution or lower provides adequate temperature data at minimal expense.

• For long-range surveillance: 17μm with 640×512 resolution delivers optimal sensitivity and detail.

Pixel pitch is not the only factor — always consider NETD, lens quality, frame rate, and interface options when selecting a thermal camera module.

FAQ

Q: What is the difference between pixel pitch and pixel size?

Pixel pitch is the spacing between the centers of adjacent pixels; pixel size is the physical dimension of the sensing element itself, which is often slightly smaller than the pitch.

Q: Does a smaller pixel pitch always mean a better thermal camera?

Not necessarily. Smaller pitches improve spatial resolution and enable more compact modules, but larger pitches generally deliver better thermal sensitivity (lower NETD) and lower cost — the right choice depends on the application.

Q: Which pixel pitch is best for long-range perimeter surveillance?

A 17μm pitch with 640×512 resolution is generally recommended for long-range surveillance, since larger pixels deliver better sensitivity (NETD below 25mK achievable).

Q: How is IFOV calculated from pixel pitch?

IFOV (mrad) = Pixel pitch (mm) / Focal length (mm) × 1000.

Future Vision Technology is a China-based manufacturer with 18 years of experience in thermal camera modules, supporting global partners through OEM/ODM services. View Thermal Camera Range