Lasers for short or Light Amplification by stimulated emission of radiation does not sound too fun does it so let's make it interesting. So Hey, In this Instructable we'll be making a target and a laser gun, which would basically be the premise of laser tag, where players shoot targets until they are eliminated. Microcontrollers such as Arduino are best for this project and are compact and suit the sensor and voltage requirements, so we'll be using an Arduino Uno for the target and an Arduino Pro Mini for the Laser Firing. Let's start Tinkering.....

⚠️Lasers are potentially hazardous please take caution and use them responsibly.

Step 1: Making the Target

Begin by cutting a circular piece of foam board roughly with a radius of 7 cm to surround it with the strip of WS2812B LEDs. Use Two Pieces of 5mm Sunboard glued together if the strip does not get a good grip on the side of the board. Use sticking tape and some hot glue to stick the LEDs to the side of the Foam Board.

Step 2: Sensing the Hit

The Laser fired at the target is sensed by the LDR's or Light Dependent Resistors which are made from semiconductors that exhibit's the property of photoconductivity and hence change their resistance when more amount of light is reflected on it which is mounted as in the above picture. I have soldered four LDR's with the LM393 comparator module so as to increase the hit target area as one LDR would be too small of a target.

I added a covering to the LDR's and Two LEDs on the sides so the target area is clearly visible in the dark. Use 220 Ohm Resistors with the LED's to Prevent Burning them out with the 5V source we are using.

Step 3: Circuit & Code

The above is the Circuit Diagram for the target, make connections as shown above and make sure no wires are loose and all solder joints are well soldered.

I have attached the code as well for uploading to the Arduino UNO after plugging it into the computer and providing the right COM port. The code basically has a counter on how many times the light is sensed by the LDR's and converts 5 LEDs to Red from Green and as we keep reflecting light on the sensor or targeting it with a laser in our case it goes on making more 5 LEDs red, The target is destroyed when the entire strip of 30 LED's Starts Blinking Red.

Target.ino
Download

Step 4: Making the Laser Trigger

I've used a simple toy gun to fit the electronics of the trigger. The brain behind the trigger is an Arduino Pro Mini which has the Attached Code uploaded to it via an FTDI breakout board. The Trigger has 2 Push buttons one for firing and one for reloading. The Laser Fires for About 40 milliseconds when Push Button 1 is Pressed and continues to fire until the threshold of 20 fires is over after which reloading or pressing the push button 2 is required which I have set to a reload time of 5 seconds.