DEFINITION OPTICS IS

Optics is the branch of physics that describes the behavior and properties of light and the interaction of light with matter. Optics explained and characterized by optical phenomena. The word comes from the Latin optics ὀπτική, meaning the display.

The field of optics usually describes the properties of visible light, infrared and ultraviolet light, but as the light is an electromagnetic wave, a similar phenomenon also occurs in the X-rays, microwaves, radio waves, and other forms of radiation elektromagnetikdan similar symptoms as well as

in the charge particle beam ( charged beam). Optics can generally be considered as part darikeelektromagnetan. Some optical phenomena depend on the quantum nature of light related to several fields of quantum optics hinggamekanika. In practice, most of the optical phenomena can be calculated using daricahaya electromagnetic properties, as described by Maxwell's equations.

Field of optics have an identity, community, and conferences. Aspects of the field are often called optical science or optical physics. Applied optical sciences are often called optical engineering. Applications of optical engineering related specifically to illumination systems (illumination) is called illumination engineering. Each discipline tends to be slightly different in application, technical skills, focus, and professional affiliations. More recent innovations in optical engineering are often categorized as photonics or optoelectronics. The boundaries between these fields and the "optics" are not clear, and the terms are used differently in different parts of the world and in various industrial fields.

Due to the wide application of the science of "light" for real-world applications, the science of optics and optical engineering tend to be highly interdisciplinary. Science of optics is part of a range of related disciplines including electrical engineering, physics, psychology, medicine (especially optalmologidan optometry), and others. In addition, the most complete optical behavior, as described in physics, is unnecessarily complicated for most problems, so a simple model can be used. Simple model is sufficient to explain most of the behavior of optical phenomena and ignore irrelevant and / or not detected on a system.

In the free space at the speed of a traveling wave c = 3 × 10^8 meters / second. When entering a particular medium (dielectric or nonconducting) wave with a velocity v, which is characteristic of the material and less than besarnyakecepatan light itself (c). Comparison of the speed of light in a vacuum to the speed of light in a medium is the refractive index of the material n as follows: n = c / v

Classical optics

 Before quantum optics became important, asarnya consists of classical electromagnetic applications and high-frequency approach to light. Classical optics is divided into two main branches: geometrical optics and physical optics.

Geometric optics, or ray optics, describes light propagation in the form of "light". Beam deflected at the interface between two different media, and can be curved in a medium in which the index-refraksinya a function of position. "Ray" in geometric optics is an abstract object, or "instrument", which is parallel to the optical wavefront darigelombang actually. Geometrical optics provides rules for the deployment of these rays through the optical system, which shows how the actual wavefront will spread. This is a significant simplification of optics, and fails to take into account many important optical effects such as diffraction and polarization. But this is a good approach, if the wavelength of light is very small compared to the size of the structures that interact with it. Geometric optics can be used to describe the geometric aspects of the depiction of light (imaging), including optical aberration.

Geometrical optics is often simplified further by paraksial approach, or "small angle approach." Mathematical behavior then becomes linear, allowing optical components and systems described in terms of a simple matrix. This leads to the Gauss optical techniques and ray tracing paraksial, used untui first order optical systems, such as estimating the position and magnification of the image and the object. Propagation is an extension of the Gaussian beam optics paraksial provide more accurate models of coherent radiation like laser beams. While still using paraksial approach, this technique takes into account diffraction, and allows calculation of the laser beam magnification comparable to the distance, and the minimum size that can be focused beam. Gaussian beam propagation bridge the gap between geometric and physical optics.

Physical optics or wave optics form the Huygens principle and modeling the propagation of complex wavefronts through optical systems, including amplitude and phase of the wave. This technique, which is usually applied numerically on a computer, it can calculate the effects of diffraction, interference, polarization, and other complex effects. But that the approximation is used, so it is not completely model the electromagnetic wave theory of light propagation. Complete model is much more computationally demanding, but can be used to solve small problems that require more accurate solution.

source : http://id.wikipedia.org/wiki/Optika

Penemuan sinyal Misterius Dari Planet Glise

Para ilmuwan baru-baru ini menemukan planet 'kembaran Bumi' yang berada di luar tata surya. Namanya, Planet Gliese 581g.  Nama lain yang kendengarannya lebih indah adalah 'Dunia Zarmina'. Penemuan itu merupakan hasil pengamatan selama 11 tahun oleh para ilmuwan dari berbagai negara.

Para ilmuwan itu tidak cuma menemukan Dunia Zarmina, tapi juga menemukan adanya sinyal misterius yang dipancarkan dari planet yang kemudian disebutkan sebagai planet kembaran bumi itu.

Adalah Dr Ragbir Bhathal, ilmuwan dari University of Western Sydney yang melihat sinyal aneh itu pada Desember 2008 -- jauh sebelum diumumkan bahwa ada planet yang bisa dihuni mahluk hidup di orbit bintang cebol, Gliese 581.

Bhathal yang adalah anggota organisasi SETI (search for extraterrestrial intelligence) -- organisasi yang bertujuan membuka kontak dengan kehidupan lain di luar Bumi -- sedang mengamati langit ketika ia menemukan sinyal 'mencurigakan' dari area galaksi di mana Gliese 581g bermukim.

Penemuan ini menguatkan  dugaan bahwa  Gliese 581g adalah planet paling mirip Bumi yang pernah ditemukan. Adakah kehidupan di sana?

Penemuan Bhathal hanya sebulan sebelum para astronom mengumumkan penemuan planet Gliese 581e yang kurang bisa dihuni (habitable) dibandingkan Gliese581g -- meski keduanya terletak di sekitar bintang yang sama yang jauhnya, sekitar 20 tahun cahaya.

"Kami menemukan sinyal yang tajam, seperti laser yang selama ini kita cari-cari. Itulah yang kami temukan, dan kami sangat bersemangat," kata Bhathal seperti dimuat situs Daily Mail, 1 Oktober 2010.

Berbulan-bulan setelah penemuannya, Bhathal yang punya reputasi sebagai 'pemburu alien dari Australia' menyapu langit untuk mencari sinyal kedua -- untuk mencari tahu apakah fenomena itu adalah nyata atau justru kesalahan instrumen. Sayang, pencariannya tak menghasilkan apapun.

Namun, penemuan planet mirip Bumi di sekitar Gliese 581 - baik 581e dan 581d, membuat imajinasi publik makin liar.

Pembuat film dokumenter, RDF dan situs jejaring sosial, Bebo menggunakan teleskop radio di Ukraina untuk mengirim sinar informasi terfokus -- berisi 500 pesan dari masyarakat dalam bentuk gelombang radio yang dirahkan ke Gliese 581.

Sementara, menteri keilmuwan Australia  saat itu mengorganisasi 20.000 pengguna Twitter untuk mengirim pesan ke bintang tetangga jauh Bumi di luar tata surya itu.

Dugaan bahwa benar ada kehidupan di seputar Gliese 581 saat ini dikuatkan oleh pendapat Dr Steven Vogt dari University of California, Santa Cruz. Ia mengaku 100 persen yakin ada kehidupan di planet itu.

Planet Gliese 581g berada di gugus bintang 'Zona Goldilocks' -- sebuah wilayah di angkasa yang kondisinya tak terlalu panas, juga tak terlali dingin bagi cairan yang membentuk laut, danau, maupun sungai.

Planet tersebut juga nampaknya memiliki selubung atmosfer, gravitasi seperti Bumi. Para ilmuwan berpendapat, jika benar, temuan ini adalah pendukung fakta bahwa alam semesta dipenuhi planet yang mirip dengan dunia manusia.

"Jumlah sistem yang diduga memiliki planet yang bisa dihuni mahluk hidup, mungkin sekitar 10 sampai 20 persen. Jika dikalikan dengan ratusan miliar bintang di Bima Sakti, ini jumlah yang besar."

Mungkin saja ada puluhan miliar sistem seperti ini di galaksi kita.

"Secara pribadi, mengingat kecenderungan kehidupan berkembang di mana pun, saya bisa mengatakan bahwa peluang bagi kehidupan di planet ini adalah 100 persen. Aku hampir tidak meragukannya," kata Vogt.