Time of Flight Sensors: What Are They?

At RAKwireless, we carry a wide range of IoT tools to help you actualize the full potential of your projects. Sensors are among some of our most popular product offerings. Compact, versatile, and easy to install, each one offers its own unique capability to help you create functional and efficient IoT solutions.

Today, we’re discussing the basics of a Time of Flight sensor—what it is, how it works, and why you might need one.

What is a Time of Flight sensor?

Time of Flight (or ToF) is the time it takes for an object or wave to travel a particular distance. This type of sensor works similarly to the way some animals use sonar abilities to measure how far away something is when navigating their environment, especially in the dark. While there are various types of ToF sensors in the market, the RAK WisBlock ToF Sensor uses a laser impulse to measure the distance between itself and the target object, with a range of up to 1.5 meters. This type of technology is often used for real-time object detection in robotics, self-driving vehicles, and traffic management. Nowadays, you can even find it in mobile phones in the form of Time of Flight cameras, which allows for facial detection capabilities.

How does a Time of Flight sensor work?

Time of Flight sensors can capture extremely precise information in two ways: via timed pulses (such as the time used in the WisBlock sensor) or through modulated waves. Let’s explore each one.

With timed pulses, a laser light is used to illuminate the target object. When this happens, light is reflected back into the sensor. The return time of this reflected light—or the speed at which the light travels back to the sensor—is then measured by a scanner, using the speed of light formula. This translates into the exact distance between the scanner and the target object.

With modulated waves, it’s a little more complex. Lighting still plays a key role in this type of measurement, but instead of measuring the speed at which light travels back, it measures the phase shift (the distance between individual waves) of the reflected light to determine the distance of the target object.

Why should you use a Time of Flight sensor?

Precise and lighting-fast measurements: ToF sensors can measure distance as fast as you can blink and often work more quickly than other types of distance sensors, such as ultrasonic sensors. Additionally, ToF sensors function more reliably because they’re unaffected by environmental factors, such as humidity, temperature, or air pressure, so they’re great for outdoor solutions.

Safe to use: The lasers used in ToF sensors are not harmful to the eyes. They often use infrared laser lights driven by modulated pulses.

Cost and power efficient: The infrared light used in many ToF sensors only requires low power, which translates into efficient energy usage and lower costs. But despite being cheaper, ToF sensors are still reliable and can capture information just as quickly.

Learn more about the RAK WisBlock Sensor and explore more sensors at the RAK store.