Light eyes cameras

Basic Principles of Imaging and Lenses


Light


Electromagnetic
Radiation

Photons

Light


These three are the same…
• Light
* pure energy

• Electromagnetic Waves
* energy-carrying waves emitted by vibrating electrons

• Photons
* particles of light



EM Radiation Travels as a Wave

c = 3 x 108 m/s

EM Radiation Carries Energy

• Quantum mechanics tells us that for photons E = hf
where E is energy and h is Planck’s constant.
• But f = c/λ
• Putting these equations together, we see that
E = hc/λ


Electromagnetic Wave Velocity

•

The speed of light is the same for all seven forms of light.

•

It is 300,000,000 meters per second or 186,000 miles per second.


The Electromagnetic Spectrum

•
•
•
•
•
•
•

Radio Waves - communication
Microwaves - used to cook
Infrared - “heat waves”
Visible Light - detected by your eyes
Ultraviolet - causes sunburns
X-rays - penetrates tissue
Gamma Rays - most energetic



The Multi-Wavelength Sun

X-Ray

UV

Composite
Infrared

Visible

Radio


EM Spectrum Relative Sizes


The Visible Spectrum
Light waves extend in wavelength from about 400 to 700 nanometers.

A Brief History of Images

Camera Obscura, Gemma Frisius, 1558

1544


Camera Obscura

"When images of illuminated objects ... penetrate through a small hole into a
very dark room ... you will see [on the opposite wall] these objects in their
proper form and color, reduced in size ... in a reversed position, owing to the
intersection of the rays". Leonardo da Vinci
(Russell Naughton)
Slide credit: David Jacobs


A Brief History of Images

Lens Based Camera Obscura, 1568

1558
1568


Jetty at Margate England,
1898.

(Jack and Beverly Wilgus)
Slide credit: David Jacobs


A Brief History of Images

1558
1568

1837

Still Life, Louis Jaques Mande Daguerre, 1837


A Brief History of Images

1558
1568

1840?

Abraham Lincoln?


A Brief History of Images

1558
1568

1837

Silicon Image Detector, 1970

1970


A Brief History of Images

1558
1568

1837

Digital Cameras

1970
1995


A Brief History of Images

1558
1568

1837

Hasselblad HD2-39

1970
1995
2006

Geometric Optics and Image Formation


Pinhole Cameras
•
•
•

Pinhole camera - box with a small hole in it
Image is upside down, but not mirrored left-to-right
Question: Why does a mirror reverse left-to-right but not top-to-bottom?