电子科技大学：干涉（PPT讲稿）Interference

Chapter 37 Interference

Soap Film Interference Chapter 37 Interference

Structural color in plants and animals The iridescent sheen of a bluebird wing or the extravagant colors of many butterflies and moths arise- not from chemistry(pigments) but from physics(interference effects)!!

Structural Color in Plants and Animals The iridescent sheen of a bluebird wing or the extravagant colors of many butterflies and moths arise - not from chemistry (pigments) but from physics (interference effects)!!

Interference of light phenomena Interference method Interference Double slit Thin film interference condition Wedge interference Newton's ring Michelson interferometer

Interference condition Double slit Thin film interference Wedge interference Newton’s ring Michelson interferometer phenomena Interference method Interference of light

Key terms: Monochromatic light Coherent waves/lights Constructive interference destructive interference Antinodal /nodal curves Interference fringes Newton's rings Nonreflective/reflective coating Michelson interferometer Michelson-Morley experiment Ether photon Plank's constant

Key terms: Monochromatic light Coherent waves/lights Constructive interference destructive interference Antinodal /nodal curves Interference fringes Newton’s rings Nonreflective/reflective coating Michelson interferometer Michelson-Morley experiment Ether photon Plank’s constant

1.phenomena of interference and coherent light 1)Phenomena of interference 2 the condition to produce interference phenomena a)why we can't see the interference from common light source The many atoms ordinarily radiate in an unsynchronized and random phase relationship b) Coherent light sources? Same frequency Constant phase difference Same polarization (oscillation direction

Same frequency Constant phase difference Same polarization (oscillation direction) 2) the condition to produce interference phenomena a) why we can’t see the interference from common light source 1.phenomena of interference and coherent Light The many atoms ordinarily radiate in an unsynchronized and random phase relationship. b) Coherent light sources? 1) Phenomena of interference

Two common way to get coherent light Dark fringe Bright fringe Screen Double slit S1 S 1 Single slit Light source (single wavelength)

p S Chose two points on the same wave front Two common way to get coherent light

2. Constructive and destructive Interference 2丌 2丌 S: E= E10 cos(at+Pio )=E1o cos(at+pu 2丌 2丌 S2:E2=E20C0s(0+20 cos(at + p20 n,n 2丌 △p=(n20-10)-n,(nh272-nf) 士2k元 constructive k=0.1 ±(2k+1)z destructive

( ) 2 ( ) 2 2 1 1 0 20 10  = − − n r − n r      destructive constructiv e k k k 0,1... (2 1) 2 =     +   =    2. Constructive and Destructive Interference ) 2 ) cos( 2 : cos( 1 1 0 1 1 0 1 0 1 1 1 1 0 1 0 S E E t r E t n r       =  +  − = + − ) 2 ) cos( 2 : cos( 2 2 0 2 2 0 2 2 2 2 0 2 0 S E E t r t n r       =  +  − = + −

jf:n0=20 ±k, constructive nii ±(k+)x, destructive s=nr Optical path length 土A入, constructive bringht δ,-8 +(k+-n, destructive dark

     +     −  = ) , destructive dark 2 1 ( k k , constructive bringht 2 1  = nr Optical path length 10 20 if : =       +  − = k destructive k constructiv e n r n r ) , 2 1 ( , 2 2 1 1  

Example: find light path difference p- δ=n11-n2 6=(r1e1+n1e1)-(r2e2+n2e2 c △6=n2L-n1L L

=n1 r1- n2 r2 = (r1 -e1 +n1e1 )- (r2 -e2 +n2e2 ) s2 s1 r2 r1 n1 p n2 s2 S1p= r1 s1 p S2p= r2  = n2 L − n1 L Example: find light path difference

caution No optical path length difference through lens The various light pass through the lens would introduce no additional optical path difference or phase shift

The various light pass through the lens would introduce no additional optical path difference or phase shift. s 1 2 s No optical path length difference through lens caution: