File slide. teoriOptka

Cahaya/Optik
Hendra Setiawan

Introduction
• Cahaya adalah gelombang yang memindahkan tenaga
tanpa perambatan massa.
• Di dalam ruang hampa warna –warna mempunyai
kecepatan perambatan yang sama, tetapi frekuensi
dan panjang gelombang masing-masing warna berbedabeda

• Cahaya merupakan gelombang transversal yang
termasuk gelombang elektromagnetik.
• Cahaya dapat merambat dalam ruang hampa dengan
kecepatan 3 x 108 m/s.

Sifat-sifat Gelombang Elektromagnetik
1. Gelombang elektromagnetik dapat merambat
dalam ruang tanpa medium
2. Merupakan gelombang transversal
3. Tidak memiliki muatan listrik sehingga bergerak
lurus dalam medan magnet maupun medan

listrik
4. Perubahan medan listrik dan medan magnet
terjadi secara bersamaan, sehingga medan listrik
dan medan magnet sefase dan berbanding lurus

Proses Melihat

Sifat Cahaya








Dapat mengalami pemantulan (refleksi)
Dapat mengalami pembiasan (refraksi)
Dapat mengalami pelenturan (difraksi)
Dapat dijumlahkan (interferensi)

Dapat diuraikan (dispersi)
Dapat diserap arah getarnya (polarisasi)
Bersifat sebagai gelombang dan partikel

Reflection and Refraction

Reflection

Law of Reflection
The incident ray
strikes the mirror.
The reflected ray
bounces off.

The angle of
incidence equals
the angle of
reflection.

Refraction

• Light rays may bend as they
cross a boundary from one
material to another, like from
air to water.
• This bending of light rays is
known as refraction.
• The light rays from the straw
are refracted (or bent) when
they cross from water back
into air before reaching your
eyes.

Refraction
When a ray of light crosses from one material to another, the
amount it bends depends on the difference in index of
refraction between the two materials.

Index of refraction
The ability of a material to bend rays of light is described by the
index of refraction (n).


Snell's law of refraction
Angle of incidence
(degrees)

Angle of refraction
(degrees)

ni sin Qi = nr sin Qr
Index of
refraction of
incident
material

Index of
refraction of
refractive
material

Dispersion


• When white light passes through a glass prism, blue
is bent more than red.
• Colors between blue and red are bent proportional
to their position in the spectrum.

Dispersion
• The variation in refractive
index with color is called
dispersion.
• A rainbow is an example of
dispersion in nature.
• Tiny rain droplets act as
prisms separating the colors
in the white light rays from
the sun.

Mirrors, Lenses, and Images
We see a world of images created on the retina of the
eye by the lens in the front of the eye.


Mirrors, Lenses, and Images
• Objects are real physical
things that give off or
reflect light rays.
• Images are pictures of
objects that are formed
in space where light
rays meet.

Optical Systems

CCD Vs CMOS

Optical Sensor

Fiber Optic

LASER
• Light Amplification by Stimulated Emission

of Radiation
• Emits very intense, monochromatic light at
high power (intensity)
• All waves in phase (unique), and parallel
• All waves are polarized in one plane

Laser Setup

Spontaneous:
Incoherent radiation
Differs in direction and phase

Advantages of Laser
• Low Beam Divergence (“Small
dot”)
• Nearly Monochromatic (“narrow
bandwidth”)
• Coherent (“constructive
interference”)


Optical Disk

Single Side vs Double Side

Hologram

Touch Screen

Candela,
Lumen, Lux