title: Light Detectors, Photoreceptors, and Imaging Systems in Nature
author:  Jerome J. Wolken 
description: <br>"The book is of value . . . as a source of inspiration for biologists who are intrigued by the subject, as well as for engineers who are looking to biological structures for new ideas."--<em>The Quarterly Review of Biology</em>
zlib_text: Understanding Electronic 
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  9. Opto-electronic components  
  Optoelectronic components (or as often referred to photo-electronic components), are electronic components which produce light 
  or react to it. Some components among them are LEDs (Light Emitting Diodes), photo transistors, photo diodes, photo resistors 
  (or LDR – Light Dependant Resistors), different visual indicators, light emitters and detectors, optocouplers, etc. Many of those 
  components can be recognized easily recognized because of the “window” on the component's case which is used to pass the 
  light. Sometimes, instead of a window, there is a small lens, which directs light to some predestined location inside of the 
  component. Some of the most important optoelectronic components are shown on photo 9.1. 
   
  9.1 Photo-electronic components  
  We already mentioned the most frequently used component of them – the LED. Basic role of a