Differential Stroboscope for Physics Lab
  A conventional stroboscope uses flashes of light to make a rapidly moving object visible. This is achieved by throwing repetitive pulses of white light on the object of specific frequency. Here an alternative approach is given in which two different colors of light(red/green) are used to make a rapidly moving object visible. As such this method has two light pulses of different colors within a single strobe period. Such a stroboscope has its own advantages in experiments over the conventional one. This article describes the construction of this stroboscope in all detail. Various aspects of its performance are discussed pictorially with reference to a simple rotating disc. This stroboscope can be used in the study/quantitative-assessment of rapidly moving objects which by default are taken to be cyclic in nature. 
Raju Baddi
physics.gen-ph