NOAO Public Affairs and Educational Outreach

What is Black?What is Black?What is Black?What is Black?

Stephen M. PompeaStephen M. Pompea

National Optical Astronomy ObservatoryNational Optical Astronomy Observatory

Tucson, ArizonaTucson, Arizona

USAUSA

Stephen M. PompeaStephen M. Pompea

National Optical Astronomy ObservatoryNational Optical Astronomy Observatory

Tucson, ArizonaTucson, Arizona

USAUSA

Dark Night Skies:Dark Night Skies:Kitt Peak and the Tohono Kitt Peak and the Tohono O’Odham NationO’Odham Nation

“This space telescope is not working as well as we would like!”

Spitzer Space Telescope in the Clean RoomSpitzer Space Telescope in the Clean Room

Spitzer Infrared Space TelescopeSpitzer Infrared Space Telescope

Overview of TalkOverview of Talk

• Why do we need black surfaces?• Is black a color?• How do we make something become “black”?• Examples of black surfaces• Designing surfaces--micro-architect?

Is Black a Color?Is Black a Color?

Yes, but ….Yes, but ….

Black depends on light levelsBlack depends on light levels

We can measure “blackness”We can measure “blackness”

Kinds of Surfaces-vocabulary

• “Diffuse” (rough)• “Specular” (smooth)

They reflect light very differently!They reflect light very differently!

Reflections are everywhere--even glass lenses reflect

Coatings are important for telescopesCoatings are important for telescopes

Painted Surface Up Close

Tungsten Hexafluoride(Grown surface)

Etched Surface (nickel)

Cross sectional view of surface

Anodized Surface (Martin Black)

How things look depends on the wavelength …How things look depends on the wavelength …

Graphs Speak to You!

New Surface for Absorbing

What is black?

• Non-reflective and absorptive• Black is related to wavelength• Specular black surfaces and diffuse black

surfaces• Surfaces roughness helps make a surface

black

Come Visit Kitt Peak!