SickSad

Long Exposure Laser Photography

Introduction

The following photos were taken using long exposure photography and an electronically controlable sweeping laser line. This produces an effect similar to the rolling shutter effect which CMOS sensors are prone to, albiet over a considerably longer exposure time.

Hardware

The hardware for this project is incredibly simple. The only part which may be tricky to obtain is the laser line generator. The one used in this project was obtained by disassembling a laser spirit level from a hardware store. Here is the rundown of parts:

  • Arduino
  • Laser line generator
  • 220 Ohm resistor
  • Continous rotation servo

A normal servo can be used with a few minor changes to the code in the software section. A continous rotation servo was used beause it was available at the time.

The 220 Ohm resistor is used to current limit the 5v supply to the laser line generator. This isn’t an ideal solution, and you may need to tweak the value of the resistor to get the optimum brightness from the laser line.

Once the laser line was attached to the servo and the whole assembly suitably mounted it looked like the following.

Software

Like the hardware, the software for the project is trivial. The arduino code simply rotates the servo between two positions. It should be noted that because a continous rotation servo is used the positions rotated between may vary for each cycle. The delays in the loop() function can be used to tweak these positions.

Arduino Servo Control
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// Arduino Servo Control
// By sicksad http://www.sicksad.com
// This code is in the public domain.

#include <Servo.h> 

Servo servo;

int stop_speed = 90;
int speed = 10;

void setup()
{
  servo.attach(9);
}

void loop()
{
  servo.write(stop_speed+speed);
  delay(2100);
  servo.write(stop_speed-speed);
  delay(1500);
}

Further Work

The hardware for this was built in less than an hour from parts that were to hand at the time. To take this work further I’d be intereset in building a multi degree-of-freedom robotic head to mount the laser on, using stepper motors or high quiality servos to provide precise controlled motion.

The cameras shutter is not synchonised to the motion of the laser line. To fix this an IR remote to trigger the shutter could be implemented using the Arduino and an IR LED.