How to Choose the Right Infrared Temperature Sensor for Your Application

Selecting an infrared temperature sensor (IR sensor) depends on your application needs, environmental conditions, and desired accuracy. Here’s a step-by-step guide to help you choose the right one:

1. Define Your Application Requirements

Ask these questions:

  • What temperature range do you need to measure?
  • What target size are you measuring?
  • What is the distance between the sensor and the target?
  • Is the target moving or stationary?
  • What material is the target made of (metal, plastic, liquid, etc.)?

2. Key Specifications to Consider

Temperature Range

Choose a sensor that covers your expected minimum and maximum temperatures.

Distance-to-Spot Ratio (D:S)

  • Also called optical resolution.
  • Higher ratios = more precise at longer distances.
  • Example: D:S = 30:1 means at 30 inches away, it reads a 1-inch spot.

Spectral Response

  • Most common is 8–14 µm (general use).
  • 1–2 µm for metals or high-temp objects.
  • Match the wavelength to your material’s emissivity characteristics.

Emissivity Adjustment

  • Make sure the sensor has adjustable emissivity (0.1–1.0) if your material isn’t perfectly black.

Response Time

  • Fast response (<100 ms) is important for moving objects or fast-changing temps.

Output Type

  • Analog (4–20mA, 0–10V), Digital (Modbus, RS485), or Thermocouple output.
  • Choose based on your system/controller compatibility.

3. Environmental Factors

  • Ambient Temperature: Some sensors have built-in cooling or protection for hot environments.
  • Dust/Moisture: Use IP-rated enclosures or protective windows for harsh environments.
  • Vibration/Shock: Choose ruggedized sensors for industrial settings.

4. Mounting and Size

  • Consider space for mounting.
  • Some sensors are compact or come with aiming lasers or sights for precise targeting.

5. Calibration and Certification

  • Look for NIST-traceable calibration if required.
  • Some industries (e.g., food or pharma) may require FDA or ISO compliance.

Example Use Case:

Measuring motor housing temperature from 3 feet away

  • Temperature range: -20°C to 150°C
  • D:S ratio: At least 30:1
  • Emissivity adjustment: Yes (for painted metal surface)
  • Output: 4–20mA to connect to PLC
  • Environment: Dusty – needs IP65 housing

We have decades of experience selling infrared (IR) temperature sensors in various applications. If you have any questions on what IR sensor is best for your application give us a call at (888) 886-8185 or send us an email.