Seeing the Objects — Optics with Reference to Luminous and Non-luminous Objects

How do we see? 

The process of seeing objects involves the detection and interpretation of light that is reflected or emitted by the objects. 

This process can be explained with reference to optics for both luminous and non-luminous objects.

Image from Unsplash 

Luminous objects:

• Luminous objects are those that emit light themselves, such as a light bulb or the Sun. 
  
• When looking at luminous object, it emits light in all directions. 
  
• Some of this emitted light reaches our eyes directly. 
• The light rays enter our eyes through the transparent outer layer called the cornea and then pass through the pupil, which controls the amount of light entering the eye. 
  
• The light rays then pass through the lens, which helps in focusing the light onto the retina at the back of the eye.
  
• The retina contains specialized cells called photoreceptors, specifically rods and cones, which are responsible for converting light into electrical signals. 
  
• The rods are more sensitive to low light conditions and help us see in dim light, while the cones are responsible for color vision and work best in bright light. 
  
• When the light reaches the retina, it stimulates these photoreceptor cells, and they convert the light into electrical signals that are sent to the brain through the optic nerve. 
  
• The brain then processes these signals, and we perceive the object as being luminous.
  

Non-luminous objects: (such as a table, book, or tree) 

• Non-luminous objects do not emit light themselves but instead reflect the light from a source, such as a light bulb or the Sun. 
  
• When light from a source falls on a non-luminous object, it interacts with the surface of the object. 
• Some of the light is absorbed by the object, while the rest is reflected back.
• Similar to the process for luminous objects, the reflected light from non-luminous objects also enters our eyes through the cornea, pupil, and lens. 
• The light is focused onto the retina, where the photoreceptor cells are stimulated, and electrical signals are generated. 
  
• These signals are then sent to the brain through the optic nerve. 
  
• The brain processes the signals and interprets them as an image of the non-luminous object.
  

In both cases, the process of seeing involves the detection and interpretation of light. For luminous objects, the light is emitted by the object itself, while for non-luminous objects, the light is reflected from a source. 

The principles of optics, including the refraction of light by the cornea and lens, the focusing of light onto the retina, and the conversion of light into electrical signals by the photoreceptor cells, play a crucial role in the perception of both luminous and non-luminous objects.