Introduction
This lab experiments was to see how light travels through the pin hole camera to form images. This was achieved through a number of steps. The basic functional principle of a pin-hole camera is that, when a shutter is opened-in this case a small pin hole, light that bounces off objects and is directed through the hole, an image is formed on a screen that is on the other side of the hole. However, this image appears to be inverted. Since the pin hole is very small, the light rays that pass through it will not overlap. This is the reason for the formation of clear images on the screen at the other end. Since the hole is small, more time was required to make the image focus but cameras require little time due to the presence of a lens that focuses light.
Procedure
One end of a cardboard tube was covered with four strips of scotch tapes. This was to act as the screen for where the image would be formed. Now cover the opening on one of the ends of the cardboard tube with a piece of aluminum foil that will tape the ends down. Then, slide the tube that has the tape to the rear end of the tube with the foil ends and that of the tube ends to be close together. Using a pin, poke a tiny hole in the center of the foil of aluminum. Now look in through the pin hole from the end of the pin scope using a nearby source of light. The pin hole should be pointed towards a source of light then peer through the opposite end.
An image is formed at the screen of the pin-hole camera. As the smaller tube is moved back and forth the image formed becomes blurred. When a second hole is made at the centre of the aluminum foil, a second light was seen to appear on the screen. There were no observable changes on the image formed on the screen when the larger tube was rotated.
When one of the holes was made large, its image on the screen became blurred. The images became blurred since more light was let in through the pin hole. The light then overlapped causing the image to loose its sharpness. With a small pin hole, light rays do not overlap since only a few rays are allowed to pass through it. However, when the hole was increased, more light rays passed through thereby overlapping leading to the formation of a blurred image. The images formed on the screen are upside down. This is because light travels in a straight path. Since there is no reflection or refraction element used to alter the path of line, the light passing through the top end of the image formed passes through the pin-hole straight to be seen as inverted at the bottom of the screen. Since light has to pass through the pin-hole in as straight line, the bottom light will hit the screen as the top and the top ray of light will hit the bottom of the screen, hence the inverted image. The human eye works with the same principle. Light passes through the pupil which acts at the pin hole. The light is focused on the retina, in this case the screen. Therefore the images are formed at the back of the eye as inverted images however; the brain processes the image reconstructing it to be the right side up.
Works Sited.
Bernd, Jähne. Practical Handbook on Image Processing for Scientific Applications. CRC Press, (1997).
David, Forsyth and Jean, Ponce. “Computer Vision” A Modern Approach. Prentice Hall, 2003.
Linda, Shapiro and George, Stockman Computer Vision. Prentice Hall, (2001).
Needham, Joseph. “Science and Civilization in China.” Volume 4, Physics and Physical Technology, Part 1, Physics. Taipei: Caves Books Ltd, 1986.
Richard, Hartley and Andrew, Zisserman Multiple View Geometry in computer vision. Cambridge University Press, (2003).
