Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science Interference and Holograms Introduction to 3D Images

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science Wavelength Wavelength is the distance between two identical points on a wave. (  lambda)

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science Frequency Frequency is the number of cycles per unit of time. (  nu) lIt is inversely proportional to the wavelength. time unit of time

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science Wavelength and Frequency Relation lWavelength is proportional to the velocity, v. lWavelength is inversely proportional to the frequency. leg. AM radio wave has a long wavelength (~200 m), therefore it has a low frequency (~KHz range). lIn the case of EM radiation in a vacuum, the equation becomes  v   c  Where c is the speed of light (3 x 10 8 m/s)

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science Light Intensity Intensity of a monochromatic light relates to the brightness of that light. –The intensity of an electromagnetic wave is proportional to the amplitude squared. Higher IntensityLower Intensity

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science Phase: –The phase of light refers to the timing and position of two or more waves. Wave Phase

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science In Phase: –Two waves that are “in phase” move together with the same motions. They are at the same cyclic position at the same time. Waves ‘In Phase’ –Example The turn signal on the car in front of you blinks at the same time as your signal.

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science Out of Phase: –Two waves that are “out of phase” do NOT move together with the same motions. At the same time they are at different cyclic positions. Waves ‘Out of Phase’ –Example The turn signal inside your car alternates with the signal of the car in front of you.

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science Interference Two waves of the same type and frequency can interfere when they meet at the same place.

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science Superposition occurs when waves combine to form a new wave. –Constructive Interference Waves in phase always superpose to add amplitudes. Interference =

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science Superposition occurs when waves combine to form a new wave. –Destructive Interference Waves out of phase superpose to subtract amplitudes. Interference =

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science Coherent waves are continuously in phase with each other. –Example: Laser Light Interference

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science The phases of incoherent waves vary randomly. Interference –Example: Light bulb

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science Interference Laser Beam-splitter Mirror Viewing Screen To observe interference: Use light that that has the same frequency, and is coherent; e.g. LASER light. Split a light beam into two paths. –amplitude splitting Allow the two beams to meet (recombine) at the same location on a viewing screen or detector.

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science Interference To observe interference: When the two beams recombine at the viewing plane they produce interference patterns of dark and bright fringes because the distances traveled by the beams determine their phases relative to each other.

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science Interference Fringes –When two or more beams of coherent light interfere, patterns appear in the form of fringes (dark and bright bands of light). Constructive interference: waves from two slits combine in phase

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science Interference Fringes –The bright spots are caused by constructive interference, and the dark spots by destructive interference Destructive interference: waves from two slits combine out of phase

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science HOLOGRAMS 3-dimensional images – Image changes as a function of viewing geometry – Light entering the eye from the hologram is the same as if reflected by original object Several different ways to create and observe holograms – All are created by illuminating object with a laser Our holograms are white light reflection holograms – Easily viewed without laser

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science DRY SIDE PROCEDURE Remove plate from box Identify emulsion side Use “shutter” to block beam Place plate against target, with emulsion against object STOP ALL MOVEMENT - REMAIN PERFECTLY STILL Remove shutter, expose plate for seconds. Replace shutter, retrieve plate, and proceed to wet side of room.

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science WET SIDE PROCEDURE Work LEFT to RIGHT (keep emulsion side UP) Developer (20-30 sec) Water Rinse (30 sec) Bleach (until clear) Wetting Agent (30 sec)

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science DRYING PLATES Use blow dryer on EMULSION SIDE Water will evaporate first, leaving “frosty” appearance Continue drying emulsion until plate is completely clear Viewing of hologram is possible at this point Do not attempt to touch emulsion side for several hours

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science SAFETY DRY SIDE –Do not look directly into laser –Be cautious with sharp edges of plate WET SIDE –Use glove(s) and safety glasses when working with chemicals –Rinse any developer off skin immediately

Imaging Science Fundamentals Chester F. Carlson Center for Imaging Science Eyewash Shower