Image Formation III Chapter 1 (Forsyth&Ponce) Cameras Lenses

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1 Image Formatio III Chapter (Forsyth&Poce) Cameras Leses Guio Gerig CS 6320 S205 (Ackowlegemets: moiie rom Marc Polleeys, UNC Chapel Hill Some materials rom Pro. Trevor Darrell,

2 Pihole size / aperture How oes the size o the aperture aect the image we get? Larger Smaller K. Grauma

3 Pihole Pictures

4 Pihole Pictures

5 Pihole Pictures

6 Pihole vs. les Shrikig hole -> sharper, but less light K. Grauma

7 Aig a les ocal poit A les ocuses light oto the ilm Rays passig through the ceter are ot eviate All parallel rays coverge to oe poit o a plae locate at the ocal legth Slie by Steve Seitz

8 Fiel o view Agular measure o portio o 3 space see by the camera Images rom K. Grauma

9 Fiel o view epes o ocal legth As gets smaller, image becomes more wie agle more worl poits project oto the iite image plae As gets larger, image becomes more telescopic smaller part o the worl projects oto the iite image plae rom R. Duraiswami

10 Cameras with leses F optical ceter (Ceter O Projectio) ocal poit A les ocuses parallel rays oto a sigle ocal poit Gather more light, while keepig ocus; make pihole perspective projectio practical K. Grauma

11 Leses Descartes law Sell s law, Law o reractio si = 2 si 2, 2 : reractio iices

12 Paraxial (or irst-orer) optics Sell s law: si = 2 si 2 Small agles: 2 2 R R γ β α h h R β γ α h h 2 2 R R h h h h

13 Thi Leses ) 2( a ' R z z R * R ' * R * ' R R spherical les suraces; thickess << raii; same reractive iex o both sies; all rays emergig rom P a passig through the les are ocuse at P. Let = (vaccuum) a 2 =. ' * R R y

14 Thick Les

15 Focus a epth o iel Image creit: cambrigeicolour.com

16 Focus a epth o iel Depth o iel: istace betwee image plaes where blur is tolerable Thi les: scee poits at istict epths come i ocus at ieret image plaes. (Real camera les systems have greater epth o iel.) circles o cousio Shapiro a Stockma

object is approximately i ocus Flower images rom

17 Focus a epth o iel How oes the aperture aect the epth o iel? A smaller aperture icreases the rage i which the object is approximately i ocus Flower images rom Wikipeia Slie rom S. Seitz

18 The epth-o-iel

19 The epth-o-iel o i i i i i i o yiels b i i i i i b b b o o o / ) ( 0 o o Similar ormula or o o o ) ( / b i i o o i ) ( 0 o b b o

20 The epth-o-iel b / ) ( ecreases with +, icreases with 0 + strike a balace betwee icomig light a sharp epth rage

21 Deviatios rom the les moel 3 assumptios :. all rays rom a poit are ocuse oto image poit 2. all image poits i a sigle plae 3. magiicatio is costat eviatios rom this ieal are aberratios

22 Aberratios 2 types :. geometrical 2. chromatic geometrical : small or paraxial rays stuy through 3 r orer optics chromatic : reractive iex uctio o wavelegth

23 Geometrical aberratios spherical aberratio astigmatism istortio coma aberratios are reuce by combiig leses

24 Spherical aberratio rays parallel to the axis o ot coverge outer portios o the les yiel smaller ocal leghts

25 Astigmatism Dieret ocal legth or iclie rays

26 Distortio magiicatio/ocal legth ieret or ieret agles o icliatio picushio (tele-photo) barrel (wie-agle) Ca be correcte! (i parameters are kow)

27 Coma poit o the axis epicte as comet shape blob

28 Chromatic aberratio rays o ieret wavelegths ocuse i ieret plaes caot be remove completely sometimes achromatizatio is achieve or more tha 2 wavelegths

29 Vigettig

Huygen s Principle: Propagation of Wavefronts. Light Rays and Geometric Optics. The Laws of Reflection

Huygen s Principle: Propagation of Wavefronts. Light Rays and Geometric Optics. The Laws of Reflection Chater 5: Relectio ad Reractio o Light Huge s Pricile: Proagatio o Waverots Ever oit o a waverot roduces wavelets. Radius o each wavelet is vt. New waverot is the surace taget to the wavelets. waverots