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Mirror Mount
A mirror mount is a device that holds a mirror. In optics research, these can be quite sophisticated devices, due to the need to be able to tip and tilt the mirror by controlled amounts, while still holding it in a precise position when it is not being adjusted. An optical mirror mount generally consists of a movable front plate which holds the mirror, and a fixed back plate with adjustment screws. Adjustment screws drive the front plate about the axes of rotation in the pitch (vertical) and yaw (horizontal) directions. An optional third actuator often enables z-axis translation. Precision mirror mounts can be quite expensive, and a notable amount of engineering goes into their design. Such sophisticated mounts are often required for lasers, interferometers, and optical delay lines. Types of mirror mount The most common type of mirror mount is the kinematic mount. This type of mount is designed according to the principles of kinematic determinacy. Typically, the movable ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stepper Motor
A stepper motor, also known as step motor or stepping motor, is a brushless DC electric motor that divides a full rotation into a number of equal steps. The motor's position can be commanded to move and hold at one of these steps without any position sensor for feedback (an open-loop controller), as long as the motor is correctly sized to the application in respect to torque and speed. Switched reluctance motors are very large stepping motors with a reduced pole count, and generally are closed-loop commutated. Mechanism Brushed DC motors rotate continuously when DC voltage is applied to their terminals. The stepper motor is known for its property of converting a train of input pulses (typically square waves) into a precisely defined increment in the shaft’s rotational position. Each pulse rotates the shaft through a fixed angle. Stepper motors effectively have multiple "toothed" electromagnets arranged as a stator around a central rotor, a gear-shaped piece of iron. The e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prism (optics)
An optical prism is a transparent optical element with flat, polished surfaces that are designed to refract light. At least one surface must be angled — elements with two parallel surfaces are ''not'' prisms. The most familiar type of optical prism is the triangular prism, which has a triangular base and rectangular sides. Not all optical prisms are geometric prisms, and not all geometric prisms would count as an optical prism. Prisms can be made from any material that is transparent to the wavelengths for which they are designed. Typical materials include glass, acrylic and fluorite. A dispersive prism can be used to break white light up into its constituent spectral colors (the colors of the rainbow) as described in the following section. Other types of prisms noted below can be used to reflect light, or to split light into components with different polarizations. Types Dispersive ''Dispersive prisms'' are used to break up light into its constituent spectral ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coma (optics)
In optics (especially telescopes), the coma (), or comatic aberration, in an optical system refers to aberration inherent to certain optical designs or due to imperfection in the lens or other components that results in off-axis point sources such as stars appearing distorted, appearing to have a tail (coma) like a comet. Specifically, coma is defined as a variation in magnification over the entrance pupil. In refractive or diffractive optical systems, especially those imaging a wide spectral range, coma can be a function of wavelength, in which case it is a form of chromatic aberration. Overview Coma is an inherent property of telescopes using parabolic mirrors. Unlike a spherical mirror, a bundle of parallel rays parallel to the optical axis will be perfectly focused to a point (the mirror is free of spherical aberration), no matter where they strike the mirror. However, this is only true if the rays are parallel to the axis of the parabola. When the incoming rays stri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Two Broadband Dielectric Mirrors
2 (two) is a number, numeral and digit. It is the natural number following 1 and preceding 3. It is the smallest and only even prime number. Because it forms the basis of a duality, it has religious and spiritual significance in many cultures. Evolution Arabic digit The digit used in the modern Western world to represent the number 2 traces its roots back to the Indic Brahmic script, where "2" was written as two horizontal lines. The modern Chinese and Japanese languages (and Korean Hanja) still use this method. The Gupta script rotated the two lines 45 degrees, making them diagonal. The top line was sometimes also shortened and had its bottom end curve towards the center of the bottom line. In the Nagari script, the top line was written more like a curve connecting to the bottom line. In the Arabic Ghubar writing, the bottom line was completely vertical, and the digit looked like a dotless closing question mark. Restoring the bottom line to its original horizonta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Piezoelectricity
Piezoelectricity (, ) is the electric charge that accumulates in certain solid materials—such as crystals, certain ceramics, and biological matter such as bone, DNA, and various proteins—in response to applied mechanical stress. The word ''piezoelectricity'' means electricity resulting from pressure and latent heat. It is derived from the Greek word ; ''piezein'', which means to squeeze or press, and ''ēlektron'', which means amber, an ancient source of electric charge. The piezoelectric effect results from the linear electromechanical interaction between the mechanical and electrical states in crystalline materials with no inversion symmetry. The piezoelectric effect is a reversible process: materials exhibiting the piezoelectric effect also exhibit the reverse piezoelectric effect, the internal generation of a mechanical strain resulting from an applied electrical field. For example, lead zirconate titanate crystals will generate measurable piezoelectricity when ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rotary Encoder
A rotary encoder, also called a shaft encoder, is an electro-mechanical device that converts the angular position or motion of a shaft or axle to analog or digital output signals. There are two main types of rotary encoder: absolute and incremental. The output of an absolute encoder indicates the current shaft position, making it an angle transducer. The output of an incremental encoder provides information about the ''motion'' of the shaft, which typically is processed elsewhere into information such as position, speed and distance. Rotary encoders are used in a wide range of applications that require monitoring or control, or both, of mechanical systems, including industrial controls, robotics, photographic lenses, computer input devices such as optomechanical mice and trackballs, controlled stress rheometers, and rotating radar platforms. Technologies * Mechanical: Also known as conductive encoders. A series of circumferential copper tracks etched onto a PCB is used t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electric Motor
An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate force in the form of torque applied on the motor's shaft. An electric generator is mechanically identical to an electric motor, but operates with a reversed flow of power, converting mechanical energy into electrical energy. Electric motors can be powered by direct current (DC) sources, such as from batteries, or rectifiers, or by alternating current (AC) sources, such as a power grid, inverters or electrical generators. Electric motors may be classified by considerations such as power source type, construction, application and type of motion output. They can be powered by AC or DC, be brushed or brushless, single-phase, two-phase, or three-phase, axial or radial flux, and may be air-cooled or liquid-cooled. Standardized motors p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stick-slip Phenomenon
The stick–slip phenomenon, also known as the slip–stick phenomenon or simply stick–slip, is the spontaneous jerking motion that can occur while two objects are sliding over each other. Cause Below is a simple, heuristic description of stick–slip phenomena using classical mechanics that is relevant for engineering descriptions. However, in actuality, there is little consensus in academia regarding the actual physical description of stick–slip which follows the lack of understanding about friction phenomena in general. The generally agreed upon view is that stick–slip behavior results from common phonon modes (at the interface between the substrate and the slider) that are pinned in an undulating potential well landscape that un-pin (slip) and pin (stick) primarily influenced by thermal fluctuations. However, stick–slip frictional behaviour is encountered over a wide range of length scales from the atomic up to the tectonic, and there is no single underlying physical m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photoelasticity
Photoelasticity describes changes in the optical properties of a material under mechanical deformation. It is a property of all dielectric media and is often used to experimentally determine the stress distribution in a material, where it gives a picture of stress distributions around discontinuities in materials. Photoelastic experiments (also informally referred to as ''photoelasticity'') are an important tool for determining critical stress points in a material, and are used for determining stress concentration in irregular geometries. History The photoelastic phenomenon was first discovered by the Scottish physicist David Brewster, who immediately recognized it as stress-induced birefringence. That diagnosis was confirmed in a direct refraction experiment by Augustin-Jean Fresnel.A. Fresnel, "Note sur la double réfraction du verre comprimé" (read 16 September 1822), ''Annales de Chimie et de Physique'', Ser. 2, vol. 20, pp. 376–83 (nominally for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deformation (engineering)
In engineering, deformation refers to the change in size or shape of an object. ''Displacements'' are the ''absolute'' change in position of a point on the object. Deflection is the relative change in external displacements on an object. Strain is the ''relative'' internal change in shape of an infinitesimally small cube of material and can be expressed as a non-dimensional change in length or angle of distortion of the cube. Strains are related to the forces acting on the cube, which are known as stress, by a stress-strain curve. The relationship between stress and strain is generally linear and reversible up until the yield point and the deformation is elastic. The linear relationship for a material is known as Young's modulus. Above the yield point, some degree of permanent distortion remains after unloading and is termed plastic deformation. The determination of the stress and strain throughout a solid object is given by the field of strength of materials and for a structu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Table
An optical table is a vibration control platform that is used to support systems used for laser- and optics-related experiments in science, engineering and manufacturing. The surfaces of these tables are designed to be very rigid with minimum deflection so that the alignment of optical elements remains stable over time. Many optical systems require that vibration of optical elements be kept small. As a result, optical tables are typically very heavy and incorporate vibration isolation and damping features in their structure. Many use pneumatic isolators that act as mechanical low-pass filters, reducing the ability of vibrations in the floor to cause vibrations in the tabletop. The surface of an optical table is typically stainless steel with a rectangular grid of tapped holes in either metric or imperial units: * metric: M6 on a 25 mm grid * imperial: ¼"-20 UNC on a 1" (25.4 mm) grid Optical breadboards, benches, and rails are simpler structures that perform a simil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
