Have you ever been thinking how a robot can figure out when is light and when is darkness? The answer is simple and contains only two words – light sensor. This little and simple sensor can be used in robotics to create a vision for a robot in order to move autonomously.
A light sensor has the role to detect the light and the result is translated into output analog value. The sensor output depends by light intensity and has low or high values. The robot can be programmed to react when the light sensor detects a certain amount of light.
In some words, a light sensor is a simple robotic part that uses light sensitive materials like Galium to generate signals. When a photon hits the Galium a small signal is generated.
A light sensor is not an expensive sensor and is used widely in many fields starting with toys, robots, gadgets and appliances.
A cheap price is one of the advantages of a light sensor, but at the same time, this type of sensor cannot be used for precise light measurements. Another advantage is that the sensor is powered only when the light is sensed, otherwise the sensor has zero energy consumption. With analog output the sensor requires a converter to take the analog output and converted into digital output. This is another disadvantage of this type of sensor.
How light sensor works
Before starting the list with light sensors, I would like to write few words about how the light sensor works. As I said before, a light sensor is simple and is used for light detection. On the market are many types of sensors with slightly different way of works. At least one thing is common to all light sensors available. All of these use a photocell or photoresistor to detect the presence of light. When the light is detected by a photocell or photoresistor the value of the output signal is changed. A converter takes the analog signal and convert into digital output.
Light sensors list
In this article, I reviewed thirteen light sensors designed to be integrated in robotics projects with light detecting requirements.
01. Mini Photocell
Mini Photocell is the smallest and cheapest light sensor designed by Sparkfun. The sensor changes his light resistance when the light is applied on his detecting surface. The range of resistance is between ~1k Ohm when the sensor is supposed to light, and can rise up to ~10k Ohm when the sensor is in the dark.
Mini Photocell has a low price and can be used in robotics projects with light detecting requirements and low budget.
02. SeeedStudio Light Sensor
SeeedStudio design a low price light sensor that uses the GL5528 photoresistor for light detection and his intensity. The resistance of the sensor decreases the value when the light intensity is high, and increase the value of resistance when the light intensity is low. Even is one of the cheapest light sensors on the market, the SeeedStudio Light Sensor returns accurate values in order to detect the intensity of light.
Integrated into robots, the sensor can be used for monitoring as well as light control robots.
03. DFRobot Light Sensor
Designed and build by DFRobot the sensor works with Cds Photoresistor and change the output voltages when light intensity changes. In the dark the output value is low while in the light the analog output value is high and reaches 5 Vdc. The sensor is designed to work with an Arduino board and on the manufacturer site can be found a sample code to program the robot in order to take a decision based on sensor values.
04. Inex Light Sensor Board
Designed by Inex, the light sensor uses an LDR (Light dependent resistor) or Photoresistor to detect the light. The output is proportional to the light intensity. With a design based on robotics integration the sensor can be integrated with microcontrollers and logic circuits due to a friendly interface.
05. Parallax QTI Light Sensor
This little sensor is designed to be used in robotics projects like line following or for detection of different shades of colors. Designed by Parallax, QTI Light Sensor works using an infrared emitter / receiver and measure the infrared reflected from a surface.
It could be used with analog and digital output and has a friendly interface for any Parallax microcontrollers.
06. Sparkfun LilyPad
Sparkfun is again on our list with another powerful light sensor with the code name LilyPad. The sensor is designed especially to be used with Arduino Lilypad Main Board or with wearable e-textile technology. The output is analog with the higher value of 5V when is supposed to the light.
07. .NET Gadgeteer Module
.NET Gadgeteer is a light sensor used to measure the intensity of light. The sensor is useful to be used in robotics projects that require determining the value of ambient light in the environment.
Designed by Sparkfun, the VCNL4000 is two sensors in one. It can be used as an infrared proximity sensor as well as light detecting sensor. The sensor can be useful in robots designed for proximity application without any physical contact.
DFRobot company is again in our books with another powerful light sensor designed to have a high resolution and used for application that requires a wide range of action.
10. Ambient Light Sensor
Designed by ioBridge, the ambient light sensor uses a CdS photocell for light intensity measure and the sensitivity can be adjusted using a potentiometer. It has analog output signal and has a friendly interface.
11. Color Light Sensor
Build by Sparkfun, the color light sensor was designed to be used almost in robotics projects that require color light detection. It has small dimensions and can be easily integrated in any robotic platform.
12. Vex Light Sensor
Vex Light Sensor is one of the most common and advanced light sensor used in robotics. The sensor detection module is based on photocell that reacts to light. Vex Light Sensor has analog input and can be used for a range between 0 to 6 feet. Used in robotics the sensor is a great resource with advanced features in autonomous function. This sensor is one of the “most expensive” and at the same time is one of the best and simplest light sensors.
ColorPAL is the latest light detection sensor from our list, and is one of the most advanced sensors. Designed by Parallax, this tiny sensor can be used for light and color detection. It can detect a wide range of colors using an LED for illumination. ColorPAL comes with a simple interface and uses simple serial protocol when color is detected and generated.