GP-B — Technology. Annurev.fluid.35.101101.161128.pdf (application/pdf Object) Multiphoton intrapulse interference phase scan. Theory[edit] A MIIPS-based device consists of two basic components controlled by a computer: a pulse shaper (usually a liquid crystal based spatial light modulator - SLM) and a spectrometer. The pulse shaper allows manipulation of the spectral phase and/or amplitude of the ultrashort pulses. The spectrometer records the spectrum of a nonlinear optical process such as second harmonic generation produced by the laser pulse. The MIIPS process is analogous to the Wheatstone bridge in electronics. A well-known (calibrated) spectral phase function is used in order to measure the unknown spectral phase distortions of the ultrashort laser pulses.
Typically, the known superimposed function is a periodic sinusoidal function that is scanned across the bandwidth of the pulse. MIIPS is similar to FROG in that a frequency trace is collected for the characterization of the ultrashort pulse. The phase scan in MIIPS is realized with introducing a well-known reference function, , of the pulse. . And. . , the. Femtosecond pulse shaping. In optics, femtosecond pulse shaping refers to manipulations with temporal profile of an ultrashort laser pulse.
Pulse shaping can be used to shorten/elongate the duration of optical pulse, or to generate complex pulses. Introduction[edit] Fig. 1: Schematic diagram of a Pulse Shaper Generation of sequences of ultrashort optical pulses is key in realizing ultra high speed optical networks, Optical Code Division Multiple Access (OCDMA) systems, chemical and biological reaction triggering and monitoring etc. Based on the requirement, pulse shapers may be designed to stretch, compress or produce a train of pulses from a single input pulse. The ability to produce trains of pulses with femtosecond or picosecond separation implies transmission of optical information at very high speeds.
In ultrafast laser science pulse shapers are often used as a compliment to pulse compressors in order to fine-tune high-order dispersion compensation and achieve transform-limited few-cycle optical pulses.[1] Spatial light modulator. SLMs are used extensively in holographic data storage setups to encode information into a laser beam in exactly the same way as a transparency does for an overhead projector. They can also be used as part of a holographic display technology. SLMs have been used as a component in optical computing.
They also often find application in holographic optical tweezers. Electrically addressed spatial light modulator (EASLM)[edit] An LCD-based reflection EASLM. As its name implies, the image on an electrically addressed spatial light modulator is created and changed electronically, as in most electronic displays. Optically addressed spatial light modulator (OASLM)[edit] The image on an optically addressed spatial light modulator, also known as a light valve, is created and changed by shining light encoded with an image on its front or back surface. They are often used as the second stage of a very-high-resolution display, such as one for a computer-generated holographic display. See also[edit] Lisefboard.pdf (application/pdf Object) Beam Bagged: "Reverse Laser" Functions as Near-Perfect Light Absorber.
Since they were invented 50 years ago, lasers have become extraordinarily commonplace. Anyone with a few dollars to spare can get themselves a laser pointer, and every CD, DVD or Blu-ray player uses a laser to read the bits encoded on discs. (It goes without saying that the same is true of those old LaserDisc players.) Just about everyone knows how lasers work, at least on the most superficial level—a concentrated beam of light comes out when energy goes in.
But what if that same process could be run in reverse, like a movie run backward? Last year, a group of physicists at Yale University proposed a way to do just that with something called a time-reversed laser. But the anti-laser does not work for any old light source; the absorption is specific to narrow frequencies of so-called coherent light—light whose waves are synchronized—which is what an ordinary laser emits. A different phase shift does just the opposite, reducing the absorption of the material. Matter & Energy. PHOTOGRAPHING THE AURORA BOREALIS. Auroras, sometimes called the northern and southern lights are natural light displays in the sky. In order to see an Aurora, one usually needs a dark sky (no bright moon, no city lights) and relatively clear weather.
Auroras usually occur near the magnetic poles of the earth and occur most often during the equinoxes. Note that the magnetic poles of the earth do not coincide with the geographic poles. For example, the Magnetic North Pole is located in the Arctic Islands of Northern Canada. The name Aurora Borealis is attributed to Pierre Gassendi, a 17th century French philosopher, astronomer and mathematician.
He named the natural light display for Aurora, the Roman goddess of dawn and Boreas which was the Greek name for the north wind. Charged “solar wind” particles (mostly electrons) travel from the Sun towards the earth at high speeds. Oxygen atoms, for example, emit photons in two typical colors: green and red. The red Aurora tends to be at higher altitudes than the green Aurora. Thide_OAM_in_radio.pdf (application/pdf Object)