Infrared Thermometer (aka. Laser Temp Gun)

A battery-powered infrared thermometer with a laser pointer built with an ESP8266 microcontroller and an MLX90614 sensor.

Features

• Measures ambient and target object temperature with the MLX90614 infrared sensor.
  • -40 … +125 °C for sensor temperature
  • -70 … +380 °C for object temperature
  • High accuracy of 0.5 °C over wide temperature range (0 … +50 °C for both Ta and To)
  • High (medical) accuracy calibration
  • Measurement resolution of 0.02 °C
• Shoots a laser beam to mark the target object.
• Powered by a 18650 battery (Model A) or a LiFePO4 3.2V AA battery (Model D).
• Measures battery level.
• Displays measured data on the Wemos OLED shield.
• Controlled by a Wemos D1 Mini microcontroller board.
• Allows charging the battery via a TP4056 charger (Model A).

The used microcontroller board has built-in WiFi capability, therefore it is possible to transmit the measured values over the wireless network for further processing (this feature is not implemented).

On this page

• Features
• On this page
• Getting Started
  • Hardware
  • Bill of Materials
  • Wiring
  • Software
  • Prerequisites
  • Setup
  • 3D-Printed Case
• About the author

(This Table of Contents was generated with nGitHubTOC, but sompylasar's solution is also very usable.)

Getting Started

Hardware

Bill of Materials

You need the following hardware components to build this project:

• Wemos D1 Mini controller board
• Wemos OLED shield
• MLX90614 infrared sensor
• 5V laser pointer
• 220K resistor (to measure the battery level)
• On-off switch
• Momentary push button
• For Model A:
  • 18650 battery
  • 18650 battery holder
  • TP4056 battery charger board
• For Model D:
  • LiFePO4 3.2V AA battery
  • Single AA battery holder
  • M3x6 screw to mount the battery holder

Wiring

Model A:

Model D:

You can find the Fritzing file in the ./hardware folder.

Software

Prerequisites

Install the following libraries in the Arduino IDE:

• Adafruit GFX Library by Adafruit.
• Adafruit SSD1306 Wemos Mini OLED by Adafruit + mcauser
• Adafruit MLX90614 by Adafruit.

Setup

Just compile and upload the ./software/InfraredThermometer/InfraredThermometer.ino file from this repository and you are done! No additional configuration is necessary.

3D-Printed Case

I designed a 3D printable case only for Model D. It's more a part-holder bone than a full housing, but still it is functional and I find it cool that it reveals how the device is working.

You can find the 3D printable STL and all the source files in the ./case folder.

You can print with 0.2mm layer height without support. The holes for the buttons and the battery holder mounting screw is covered with a sacrificial layer to avoid supports, so you must remove that after printing.

Shares on 3D printing community sites for comments and remixes:

• Thingiverse: https://www.thingiverse.com/thing:4222541
• PrusaPrinters: https://www.prusaprinters.org/prints/25513-infrared-thermometer-aka-laser-temp-gun

About the author

This project is maintained by György Balássy.