How to Select the Proper Pixel Pitch for Thermal Imaging Camera Modules

Pixel pitch is one of the most critical core parameters of uncooled thermal imaging camera modules. Defined as the center-to-center distance between adjacent microbolometer pixels on the infrared focal plane array (FPA), it is measured in micrometers (µm). The selection of pixel pitch directly determines the module’s spatial resolution, thermal sensitivity, detection range, physical size, power consumption and overall cost. A mismatched pixel pitch will lead to insufficient imaging detail, poor temperature measurement accuracy, or excessive cost and volume waste.

1. Basic Core Principle of Pixel Pitch Selection

The core of pixel pitch selection lies in balancing spatial resolution and thermal sensitivity, together with adapting to product SWaP-C (Size, Weight, Power, Cost) constraints. There is an inherent physical trade-off between different pixel pitch specifications:

Smaller pixel pitches mean denser pixel arrangement on the FPA, which improves spatial resolution and long-distance detection capability, and supports miniaturization of modules and lenses. However, smaller pixels have a single pixel with less infrared receiving area, resulting in relatively lower thermal sensitivity and higher manufacturing difficulty and cost.

Larger pixel pitches provide a larger single photosensitive area, which can capture more infrared radiation signals, effectively reducing noise and achieving a lower Noise Equivalent Temperature Difference (NETD), namely higher thermal sensitivity. But it will reduce imaging fineness, require larger optical lenses, and increase the overall volume and weight of the equipment.

2. Key Evaluation Indicators for Pixel Pitch Selection

2.1 Spatial Resolution and IFOV

Instantaneous Field of View (IFOV) is a core indicator to judge detection and recognition capability, calculated by the formula: IFOV (mrad) = Pixel pitch (mm) / Focal length (mm) × 1000. A smaller pixel pitch brings a smaller IFOV, which means the module can capture more detail of the target object, realize clear imaging of tiny targets, and effectively extend the effective detection and recognition distance. For scenarios requiring long-distance monitoring and tiny defect detection, small-pitch sensors are a must.

2.2 Thermal Sensitivity (NETD)

NETD characterizes the minimum temperature difference that the thermal module can distinguish. The smaller the NETD value, the higher the thermal sensitivity and the stronger the ability to identify subtle temperature anomalies. Large-pitch pixels have a larger infrared absorption area, with lower signal noise and more stable temperature detection performance, showing better imaging effects in low-temperature contrast and complex low-observation environments. Scenarios such as fire rescue and low-light environment monitoring prioritize large-pitch modules with high sensitivity.

2.3 SWaP-C Constraints

Pixel pitch determines the overall size of the FPA sensor under the same resolution. Modules with small pixel pitches (8–12µm) have smaller sensor sizes, matching miniaturized germanium infrared lenses, which can greatly reduce the size, weight and power consumption of the whole machine. This is crucial for portable devices and wearable thermal devices etc. with strict volume and weight limits. In contrast, large-pitch modules (17–35µm) have mature manufacturing processes, lower material and production costs, and are more suitable for fixed industrial monitoring equipment with loose SWaP requirements.

2.4 Application Environment Accuracy Requirements

Radiometric temperature measurement scenarios have higher requirements for pixel pitch matching. Small-pitch high-resolution modules can realize multi-pixel coverage of tiny heating points, ensuring accurate temperature measurement of micro-defects in industrial equipment. For ordinary regional temperature monitoring and over-temperature alarm scenarios, large-pitch low-cost modules can meet the basic demand.

3. Scenario-Based Pixel Pitch Selection Standards

3.1 8–10µm Ultra-fine Pitch (High-end Precision Scenarios)

This specification is the mainstream high-end pixel pitch for industrial thermal modules, usually matched with 640×512 high resolution. It has ultra-high spatial resolution, ultra-small IFOV, and can identify millimeter-level tiny temperature defects. Despite slightly higher power consumption and cost, its miniaturized size and extreme imaging detail are irreplaceable.

Applicable scenarios: Precision industrial defect detection, high-definition security surveillance, aerospace monitoring, high-precision building energy efficiency detection.

3.2 12µm Standard Small Pitch (Balanced Universal Scenarios)

12µm is the most cost-effective mainstream specification in the commercial market, perfectly balancing resolution, sensitivity, volume and cost. Compared with 17µm modules, it has 42% higher pixel density and smaller volume, and its thermal sensitivity is sufficient to meet most commercial scenarios, avoiding the high cost of ultra-fine pitch modules.

Applicable scenarios: Outdoor security monitoring, electrical equipment routine detection, vehicle-mounted night vision, building pipeline detection.

3.3 17µm Medium Pitch (High-Sensitivity Scenarios)

17µm is a mature traditional specification with excellent thermal sensitivity (NETD can be lower than 25mK), low imaging noise and strong environmental adaptability. Its process technology is stable and reliable, with lower after-sales failure rate.

Applicable scenarios: Fire smoke penetration imaging, forest fire prevention monitoring, wildlife observation, law enforcement night patrol, long-distance outdoor surveillance.

3.4 25–35µm Large Pitch (Cost-Sensitive Basic Scenarios)

Large-pitch modules are low-cost entry-level products, matched with low resolution such as 160×120 and 80×60. They have simple structure, low power consumption and extremely low cost, but poor imaging fineness and temperature measurement accuracy.

Applicable scenarios: Indoor temperature early warning, IoT intelligent temperature monitoring, simple equipment over-temperature protection, low-cost civilian temperature screening.

4. Common Selection Mistakes to Avoid

Mistake 1: Blindly pursuing ultra-small pixel pitch. Excessively high precision will lead to unnecessary cost and power consumption waste. For ordinary regional temperature alarm scenarios, 17µm or 25µm modules can fully meet the demand.

Mistake 2: Ignoring lens matching. Small-pitch high-resolution modules need to be matched with high-precision germanium lenses. Ordinary low-cost lenses will restrict the imaging performance of small-pitch sensors and fail to give play to resolution advantages.

Mistake 3: Prioritizing pitch over overall parameters. Pixel pitch is not the only criterion. When selecting a module, it is necessary to comprehensively match NETD, frame rate, resolution and interface parameters to avoid single-index optimization and overall performance imbalance.

5. Practical Pixel Pitch Selection Guide Example (Ready-to-Use)

5.1 Core Parameter Selection Reference Table (Standard Example)

5.2 Typical Scenario Dedicated Selection Examples

Example 1: Fire Rescue Thermal Imager Project
Demand constraints: Work in smoke & low-light environment, priority to temperature sensitivity, no strict miniaturization requirement
Selection result: 17µm + 384×288 resolution
Reason: Larger pixel area brings lower NETD, can capture weak temperature signals in complex environments, stable and reliable for emergency scenarios.

Example 2: High-Precision Industrial Detection Equipment
Demand constraints: Identify 1mm-level micro hot spots of mechanical parts, require high temperature measurement accuracy
Selection result: 8µm + 640×512 resolution
Reason: Ultra-small pitch reduces IFOV, realizes multi-pixel coverage of tiny hot spots, meets high-precision detection standards.

Example 3: Civil Low-Cost Temperature Alarm Terminal
Demand constraints: Only regional over-temperature warning, strict cost control, low power consumption requirement
Selection result: 25µm + 160×120 resolution
Reason: Meets basic temperature monitoring functions, greatly reduces module and overall equipment cost.

6. Summary

For most commercial and industrial universal scenarios, 12µm pixel pitch is the optimal choice with balanced performance and cost. For high-precision detection and high-definition imaging scenarios, select 8–10µm ultra-fine pitch modules. For low-observation, high-sensitivity dependent scenarios such as fire rescue, 17µm medium pitch is more suitable. For low-cost, basic temperature monitoring scenarios, 25–35µm large-pitch modules can be prioritized to control costs.

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* Future Vision Technology is one leading CCTV surveillance solutions provider from China. With more than 10 years R&D and engineering experience, we are dedicated to support our partners and clients based on OEM/ODM services.