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

• 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/emission-theory/6a00d83542d51e69e20120a932bfac970b-500wi_20111012154439_Resized.jpg

• http://memegenerator.net/instance/13469306• http://images2.wikia.nocookie.net/__cb20081114033730/uncyclopedia/images/1/11/BrightLight.jpg

References (Continued)

• 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