|
Densitometer
A densitometer is a device that measures the degree of darkness (the optical density) of a photographic or semitransparent material or of a reflecting surface. The densitometer is basically a light source aimed at a photoelectric cell. It determines the density of a sample placed between the light source and the photoelectric cell from differences in the readings. Modern densitometers have the same components, but also have electronic integrated circuitry for better reading. Types *Transmission densitometers that measure transparent materials *A transmission densitometer used to measure transparent surfaces measure color transparencies. Film & transparent substrates are some examples of common transparent surface measures. *Reflection densitometers that measure light reflected from a surface of any state. Photography applications Some are capable of both types of measurements selectable by a switch. They are used in film photography to measure densities of negatives with the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microdensitometer
A microdensitometer is an optical instrument used to measure optical densities in the microscopic domain. J. C. Dainty and R. Shaw, ''Image Science'' (Academic, New york, 1974).T. H. James, ''The Theory of the Photographic Process'' (Eastman Kodak, Rochester, 1977).F. J. Duarte, ''Tunable Laser Optics'' (Elsevier Academic, New York, 2003) Chapter 10. A well-known microdensitometer, used in the photographic industry, is a granularity instrument or granularity machine. The granularity measurement involves the use of an optical aperture, 10-50 micrometers in diameter, and in the recording of thousands of optical density readings. The standard deviation of this series of measurements is known as the ''granularity'' of the measured transmission surface, optical film, or photographic film, in particular . An alternative version to the traditional point-by-point microdensitometer is the beam expanded laser microdensitometer.F. J. Duarte, Electro-optical interferometric microdensitome ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Densitometry
Densitometry is the quantitative measurement of optical density in light-sensitive materials, such as photographic paper or photographic film, due to exposure to light. Overview Optical density is a result of the darkness of a developed picture and can be expressed absolutely as the number of dark spots (i.e., silver grains in developed films) in a given area, but usually it is a relative value, expressed in a scale. Since density is usually measured by the decrease in the amount of light which shines through a transparent film, it is also called ''absorptiometry'', the measure of light absorption through the medium. The corresponding measuring device is called a densitometer (''absorptiometer''). The decadic (base-10) logarithm of the reciprocal of the transmittance is called the absorbance or ''density''. ''DMax'' and ''DMin'' refer to the maximum and minimum density that can be produced by the material. The difference between the two is the ''density range''. The density ran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Measuring Instrument
A measuring instrument is a device to measure a physical quantity. In the physical sciences, quality assurance, and engineering, measurement is the activity of obtaining and comparing physical quantities of real-world objects and events. Established standard objects and events are used as units, and the process of measurement gives a number relating the item under study and the referenced unit of measurement. Measuring instruments, and formal test methods which define the instrument's use, are the means by which these relations of numbers are obtained. All measuring instruments are subject to varying degrees of instrument error and measurement uncertainty. These instruments may range from simple objects such as rulers and stopwatches to electron microscopes and particle accelerators. Virtual instrumentation is widely used in the development of modern measuring instruments. Time In the past, a common time measuring instrument was the sundial. Today, the usual measur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrometer
A hydrometer or lactometer is an instrument used for measuring density or relative density of liquids based on the concept of buoyancy. They are typically calibrated and graduated with one or more scales such as specific gravity. A hydrometer usually consists of a sealed hollow glass tube with a wider bottom portion for buoyancy, a ballast such as lead or mercury for stability, and a narrow stem with graduations for measuring. The liquid to test is poured into a tall container, often a graduated cylinder, and the hydrometer is gently lowered into the liquid until it floats freely. The point at which the surface of the liquid touches the stem of the hydrometer correlates to relative density. Hydrometers can contain any number of scales along the stem corresponding to properties correlating to the density. Hydrometers are calibrated for different uses, such as a lactometer for measuring the density (creaminess) of milk, a saccharometer for measuring the density of sugar in a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Density
Absorbance is defined as "the logarithm of the ratio of incident to transmitted radiant power through a sample (excluding the effects on cell walls)". Alternatively, for samples which scatter light, absorbance may be defined as "the negative logarithm of one minus absorptance, as measured on a uniform sample". The term is used in many technical areas to quantify the results of an experimental measurement. While the term has its origin in quantifying the absorption of light, it is often entangled with quantification of light which is “lost” to a detector system through other mechanisms. What these uses of the term tend to have in common is that they refer to a logarithm of the ratio of a quantity of light incident on a sample or material to that which is detected after the light has interacted with the sample. The term absorption refers to the physical process of absorbing light, while absorbance does not always measure only absorption; it may measure attenuation (of trans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photoelectric Cell
A solar cell, or photovoltaic cell, is an electronic device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon.Solar Cells chemistryexplained.com It is a form of photoelectric cell, defined as a device whose electrical characteristics, such as , , or resistance, vary when exposed to light. Individual solar cell devices are often the electrica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electronics
The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons using electronic devices. Electronics uses active devices to control electron flow by amplification and rectification, which distinguishes it from classical electrical engineering, which only uses passive effects such as resistance, capacitance and inductance to control electric current flow. Electronics has hugely influenced the development of modern society. The central driving force behind the entire electronics industry is the semiconductor industry sector, which has annual sales of over $481 billion as of 2018. The largest industry sector is e-commerce, which generated over $29 trillion in 2017. History and development Electronics has hugely influenced the development of modern society. The identification of the electron in 1897, along with the subsequent invention of the vacuum tube which could amplify and rectify small ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circuitry
An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or traces through which electric current can flow. It is a type of electrical circuit and to be referred to as ''electronic'', rather than ''electrical'', generally at least one active component must be present. The combination of components and wires allows various simple and complex operations to be performed: signals can be amplified, computations can be performed, and data can be moved from one place to another. Circuits can be constructed of discrete components connected by individual pieces of wire, but today it is much more common to create interconnections by photolithographic techniques on a laminated substrate (a printed circuit board or PCB) and solder the components to these interconnections to create a finished circuit. In an integrated circuit or IC, the components and interconnections are formed on t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light
Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 terahertz, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths). In physics, the term "light" may refer more broadly to electromagnetic radiation of any wavelength, whether visible or not. In this sense, gamma rays, X-rays, microwaves and radio waves are also light. The primary properties of light are intensity, propagation direction, frequency or wavelength spectrum and polarization. Its speed in a vacuum, 299 792 458 metres a second (m/s), is one of the fundamental constants of nature. Like all types of electromagnetic radiation, visible light propagates by massless elementary particles called photons that represents the quanta of electromagnetic field, and can be analyzed as both waves an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Tools For Gene Study
Nucleic acid methods are the techniques used to study nucleic acids: DNA and RNA. Purification *DNA extraction *Phenol–chloroform extraction *Minicolumn purification *RNA extraction * Boom method * Synchronous coefficient of drag alteration (SCODA) DNA purification Quantification *Abundance in weight: spectroscopic nucleic acid quantitation *Absolute abundance in number: real-time polymerase chain reaction (quantitative PCR) *High-throughput relative abundance: DNA microarray *High-throughput absolute abundance: serial analysis of gene expression (SAGE) *Size: gel electrophoresis Synthesis *''De novo'': oligonucleotide synthesis *Amplification: polymerase chain reaction (PCR) Kinetics * Multi-parametric surface plasmon resonance *Dual-polarization interferometry * Quartz crystal microbalance with dissipation monitoring (QCM-D) Gene function *RNA interference Other *Bisulfite sequencing * DNA sequencing *Expression cloning *Fluorescence in situ hybridization *Lab-on-a-ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Density Meter
A density meter, also known as a densimeter, is a device that measures the density. Density is usually abbreviated as either \rho or D . Typically, density either has the units of '' kg/m^3 '' or '' lb/ft^3 ''. The most basic principle of how density is calculated is by the formula: : \rho = \frac Where: : \rho = the density of the sample. : m = the mass of the sample. : V = the volume of the sample. Many density meters can measure both the wet portion and the dry portion of a sample. The wet portion comprises the density from all liquids present in the sample. The dry solids comprise solely of the density of the solids present in the sample. A density meter does not measure the specific gravity of a sample directly. However, the specific gravity can be inferred from a density meter. The specific gravity is defined as the density of a sample compared to the density of a reference. The reference density is typically of that of water. The specific gravity is found by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> Light")