Detector imaging principle
Thermal infrared detectors mainly use the absorption of infrared radiation to produce temperature changes in the detector sensitive element resistance, polarization strength, potential, current, volume and other physical changes, according to the changes in these physical quantities can distinguish the target object information.
Photon detectors do not need light - thermal conversion process, due to the photoelectric effect, the sensitive element absorbs photons, directly interacting with electrons, directly generating electrical signals.
| Cooled Infrared Detector |
Uncooled Infrared Detector |
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Working Principle |
Based on the photoelectric effect generated by the absorption of infrared radiation by sensitive materials, the detection unit absorbs photons and then changes the electronic state, thus causing photonic effects such as the internal photoelectric effect and the external photoelectric effect. |
Detection of infrared radiation using the thermal effect of infrared radiation |
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Pros |
High sensitivity, long detection distance, fast response speed, stable performance |
Small size, low power consumption, low price, FPA can work at room temperature |
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Cons |
FPA requires low temperature (77K/150K/200K) environment, need to install refrigeration device, equipment consumption is large and expensive. |
Lower sensitivity, shorter observation distance, slower response time |
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Application |
Long-range monitoring, target tracking, aviation, aerospace, reconnaissance, security and surveillance |
Can meet the general border requirements and most of the civilian needs, fire alarms, industrial detection, security monitoring, etc. |
Detector Type - Uncooled Metal
Metal Housing + Glass or Lens Window
Advantages
1. High heat dissipation: metal package conducts heat quickly, suitable for medium/high power thermal imaging detectors.
2. Electromagnetic shielding: metal housing can reduce external electromagnetic interference (EMI) and improve signal stability.
3. High mechanical strength: anti-shock, anti-vibration, suitable for military, automotive and other harsh environments.
4. Good gas tightness: can be filled with inert gas (such as nitrogen) to prevent oxidation and extend the life of the detector.
Disadvantages
1. Large weight: high metal density, not conducive to portable equipment lightweight.
2. Higher cost: precision metal processing, precious metal parts, increasing manufacturing costs.
Detector Type - Uncooled Ceramic
Ceramic Substrate + Metal Cover
Advantages
1. High temperature/corrosion resistance: Ceramics (e.g. Al?O?, AlN) can withstand high temperatures of 500°C or more, making them suitable for extreme environments such as aerospace and nuclear power.
2. Low thermal resistance: Ceramics such as Aluminum Nitride (AlN) have thermal conductivity close to that of metals, and have excellent heat dissipation.
Disadvantages
1. High brittleness: easy to break, high difficulty in machining.
2. Higher cost: precision ceramic package price is higher than plastic, but lower than metal hermetic package.
Detector Type - Uncooled Wafers
Packaging done directly on wafer 
Advantages
Ultra-Miniaturization: Packaging done directly on wafer with minimal size
Integration: Compatible with CMOS process.
Low cost (high volume): wafer-level batch processing, significantly lower cost per unit
Disadvantages
Poor environmental tolerance: usually non-airtight, afraid of humidity and dust.
Weak heat dissipation: relies on silicon-based heat dissipation, may overheat in high power scenarios.
Reliability challenges: solder joints fatigue easily under thermal cycling, lower lifetime than metal/ceramic packages.
Detector type - General Cooling
Commonly cooled detectors:
Detector type: Mercury Cadmium Telluride (MCT/HgCdTe)
Start-up time: ≤8min
Frame rate: up to 100hz
Mean time to failure: ≥6000h
Detector Type - HOT Cooling 
HOT Cooling Detectors:
Detector Type: Class II Ultra Lattice
Power On Time: ≤3min
Frame Rate: 50/30hz
Mean Time to Failure: ≥20000h
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