Ibn Al-Haitham (Alhazen) – The Father of Optics

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Ibn Al-Haitham (Alhazen) –
The Father of Optics
An ACE project by Bryan Yan 2I102
Who is he?
• Muslim Scientist
• Lived during “High point of Islamic Civilization”
• Made great contributions to physics,
mathematics, astronomy and optics
• Born in Barsa
• Died at 74 in Cairo
• Known for his “Book of Optics”
Key Contributions
• Concluded that light enters our eyes and not
emitted from them
• Pinhole Camera
• Visual Perception of Optical Illusions
How do we see? – Past Theories
• Emission theory
• Supported by Euclid and Ptolemy
• Believed that light was emitted from our eyes
How do we see? – Past Theories
• Intermission theory
• Supported by Aristotle and his followers
• Believed that physical particles enter our eyes
from an object
How do we see? Disputing Past
Theories
• Light cannot reach astronomical objects once we
open our eyes
• We are blinded by bright light
How do we see? – Accepted Theory
(Basis)
• Proved that light traveled in straight lines
• Reduced reflected and refracted light rays into
vertical and horizontal components
• Pinhole Camera (more about this later)
How do we see? – Accepted Theory
• Unified version of geometrical optics and
philosophical physics to form modern physical
optics
• Images are inverted in our eyes
• The eye is a medium and lens, neither an emitter
or receiver
Pinhole Camera – What?
• Simple camera without lens
• With a single small aperture
• Usually a box, but can be done with two white
cards of which one has the hole
Pinhole Camera – When? Where?
• 1021 AD
• In “Book of Optics”
Pinhole Camera – How?
• Light passes through the small hole to form an
inverted image on the screen
• The image is dim and small, but sharp
Pinhole Camera – Why?
• Pinhole acts as a lens
• Light from surroundings pass through the pinhole,
captured on a point on the screen
• Light from above is captured below and vice
versa
Pinhole Camera – Link?
• Similar concept to eye
• Inverted and sharp image
Moon Illusion – Introduction
• Moon appears larger near the horizon than it
does while higher up in the sky
• Illusion still debated
• Alhazen’s reasoning most widely available and
accepted
Moon Illusion – Alhazen’s Principle
• Judging the distance of an object depends on
• There being an uninterrupted sequence of
intervening bodies between the object and the
observer
Moon Illusion – Alhazen’s Conclusion
• When the Moon is high in the sky there are no
intervening objects, so the Moon appears close
• The perceived size of an object of constant
angular size varies with its perceived distance
References
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http://en.wikipedia.org/wiki/Alhazen
http://www.ibnalhaytham.net/
http://www-history.mcs.st-andrews.ac.uk/Biographies/Al-Haytham.html
http://harvardmagazine.com/2003/09/ibn-al-haytham-html
http://www.britannica.com/EBchecked/topic/738111/Ibn-al-Haytham
http://en.wikipedia.org/wiki/Pinhole_camera
http://en.wikipedia.org/wiki/Camera_obscura
http://www.muslimheritage.com/topics/default.cfm?articleID=382
http://inventors.about.com/od/pstartinventions/a/stilphotography.htm
http://lecerveau.mcgill.ca/flash/capsules/articles_pdf/moon_illusion.pdf
http://islamsci.mcgill.ca/RASI/BEA/Ibn_al-Haytham_BEA.htm
http://www.ishim.net/ishimj/4/10.pdf
http://www.newworldencyclopedia.org/entry/Ibn_al-Haytham
http://www.iis.ac.uk/view_article.asp?ContentID=106742
http://www.nei.nih.gov/health/eyediagram/images/NEA09.gif
http://en.wikipedia.org/wiki/Emission_theory_(vision)
http://www.popsci.com.au/galleries/craziest-scientific-theories/emissiontheory/6a00d83542d51e69e20120a932bfac970b-500wi_20111012154439_Resized.jpg
http://memegenerator.net/instance/13469306
http://images2.wikia.nocookie.net/__cb20081114033730/uncyclopedia/images/1/11/BrightLight.jpg
References (Continued)
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http://images.tutorvista.com/content/feed/tvcs/rectilinear-propagation-of-light.jpeg
http://www.healthyeyes.org.uk/index.php?id=2
http://www.bbc.co.uk/schools/scienceclips/ages/10_11/see_things_whatnext.shtml
http://www.accessexcellence.org/AE/AEC/CC/vision_background.php
http://www.pediatriconcall.com/kidscorner/yourbody/our_eyes.aspx
http://www.quora.com/Human-Brain/How-can-we-see-images-in-our-mind
http://en.wikipedia.org/wiki/Physical_optics
http://www.yorku.ca/eye/invert.gif
http://en.wikipedia.org/wiki/Aperture
http://en.wikipedia.org/wiki/File:Pinhole-camera.svg
http://www.nei.nih.gov/healthyeyes/eye_images/Normal.gif
http://www.islamic-study.org/iais-images/al-haytham-optics%20book.gif
http://www.thegeminigeek.com/wp-content/uploads/2010/03/Pinhole-Camera.jpg
http://www.curriculumbits.com/physics/how-does-a-pinhole-camera-work/
http://wiki.answers.com/Q/How_does_a_Pinhole_camera_work
http://wwwx.cs.unc.edu/~sud/courses/comp235/pinhole-principle.gif
http://cw.psypress.com/zaidel/images/figure3_4big.jpg
http://www.derekshirlaw.co.uk/wp-content/uploads/2012/02/moon.jpg
http://en.wikipedia.org/wiki/File:Harvest_moon.jpg
http://people.umass.edu/~blaylock/p284/cl0024_hst.gif

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