what is spectrophotmeter?

Answer 1

In physics,spectrophotometry is the quantitative study of electromagnetic spectra. It is more specific than the general term electromagnetic spectroscopy in that spectrophotometry deals with visible light, near-ultraviolet, and near-infrared. Also, the term does not cover time-resolved spectroscopic techniques.
Spectrophotometry involves the use of a spectrophotometer. A spectrophotometer is a photometer (a device for measuring light intensity) that can measure intensity as a function of the color, or more specifically, the wavelength of light. There are many kinds of spectrophotometers. Among the most important distinctions used to classify them are the wavelengths they work with, the measurement techniques they use, how they acquire a spectrum, and the sources of intensity variation they are designed to measure. Other important features of spectrophotometers include the spectral bandwidth and linear range.

Perhaps the most common application of spectrophotometers is the measurement of light absorption, but they can be designed to measure diffuse or specular reflectance. Strictly, even the emission half of a luminescence instrument is a kind of spectrophotometer.

There are two major classes of spectrophotometers; single beam and double beam. A double beam spectrophotometer measures the ratio of the light intensity on two different light paths, and a single beam spectrophotometer measures the absolute light intensity. Although ratio measurements are easier, and generally stabler, single beam instruments have advantages; for instance, they can have a larger dynamic range.

Visible-region spectrophotometers

Visible region 400-700nm spectrophotometry is used extensively in colorimetry science. Ink manufacturers, printing companies, textiles vendors, and many more, need the data provided through colorimetry. They usually take readings every 10 nanometers along the visible region, and produce a spectral reflectance curve. These curves can be used to test a new batch of colorant to check if it makes a match to specifications. Traditional visual region spectrophotometers cannot detect if a colorant has fluorescence. This can make it impossible to manage color issues if one or more of the printing inks is fluorescent. Where a colorant contains fluorescence, a bi-spectral fluorescent spectrophotometer is used. There are two major setups for visual spectrum spectrophotometers, d/8 (spherical) and 0/45. The names are due to the geometry of the light source, observer and interior of the measurement chamber. Scientists use this machine to measure the amount of compounds in a sample. If the compound is more concentrated more light will be absorbed by the sample.

components: 1. The light source shines through the sample. 2. The sample absorbs light. 3. The detector detects how much light the sample has absorbed. 4. The detector then converts how much light the sample absorbed into a number.

[edit] Spectroradiometers
Spectrographic representation of the light output of an incandescent bulb (left) and a fluorescent lamp (right)
Spectrographic representation of the light output of an incandescent bulb (left) and a fluorescent lamp (right)

Spectroradiometers, which operate almost like the visible region spectrophotometers, are designed to measure the spectral density of illuminants in order to evaluate and categorize lighting for sales by the manufacturer, or for the customers to confirm the lamp they decided to purchase is within their specifications.
[edit] UV and IR spectrophotometers

The most common spectrophotometers are used in the UV and visible regions of the spectrum, and some of these instruments also operate into the near-infrared region as well. Spectrophotometers designed for the main infrared region are quite different because of the technical requirements of measurement in that region. One major factor is the type of photosensors that are available for different spectral regions, but infrared measurement is also challenging because virtually everything emits IR light as thermal radiation, especially at wavelengths beyond about 5 μm.

Historically, spectrophotometers use a monochromator to analyze the spectrum, but there are also spectrophotometers that use arrays of photosensors and, especially in the IR, there are spectrophotometers that use a Fourier transform technique to acquire the spectral information in a technique called Fourier Transform InfraRed.

The spectrophotometer measures quantitatively the fraction of light that passes through a given solution. In a spectrophotometer, a light from a lamp in a near-IR/VIS/UV spectrophotometer (typically a deuterium gas discharge lamp) is guided through a monochromator, which picks light of one particular wavelength out of the continuous spectrum. This light passes through the sample that is being measured. After the sample, the intensity of the remaining light is measured with a photodiode or other light sensor, and the transmittance for this wavelength is then calculated.

See also

* Ultraviolet-Visible spectroscopy
* Infrared spectroscopy
* Colorimeter
* Atomic Absorption Spectrophotometry

Answer 2

Definitions of Spectrophotometer on the Web:

* A photometer which measures the intensity of radiation as a function of the frequency (or wavelength) of the radiation.
www.telemet.com/weather_gloss_s.htm

* Sophisticated instrument that measures color across a visible spectrum and produces data describing the color of a given sample in terms of the three parameters in color space.
www.paperspecs.com/resources/glossary/s.htm

* A high-end device that measures a color's wavelength.
ikjeld.com/info/glossary/glossaryS.html

* An extremely accurate color measurement device using a diffraction grating to split light into its component wavelengths, which are then measured by numerous light sensors.
www.globalimaginginc.com/resources/glossary.shtml

* A device that captures colours as spectral data, thereby providing maximum accuracy in measuring and specifying colours.
www.vistek.ca/glossary/default.asp

* an instrument that measures the degree of absorption (or emission) of electromagnetic radiation by a substance. The measuring system generally includes a photomultiplier. [ Uv, ir, visible, and microwave regions of the electromagnetic spectrum may be measured in this way.]
www.cartage.org.lb/en/themes/Sciences/Chemistry/Organicchemistry/Common/Common.htm

* Instrument used to measure the index of refraction of colour.
www.c-latitude.com/glossary.asp

* A spectrophotometer is a detector instrument that measures the amount of monchromatic light passing through a solution by means of an adjustable monochromator such as a prism or diffraction grating.
www.brendan.com/Glossary.htm

* A color-testing instrument used to measure the reflectance of light as a function of wave length. A&E currently uses the Datacolor system for shade matching and shade approval.
www.amefird.com/stu_glossary.htm

* An instrument designed to measure precisely the amount and value of light a given colour (typically colour patches in a printed target) reflects or transmits at each wavelength, producing spectral data. Spectrophotometers are employed with profile building applications.
www.digital-lucida.com.au/information/glossary/printgloss.html

* A light measuring device which incorporates a monchrometer to isolate and project particular wavelengths of electromagnetic radiation through a sample, and a detector to measure the amount of radiation which has passed through the sample.
www.fire.org.uk/glossary.htm

* An optical instrument to measure color or color differences from standard.
www.newpagecorp.com/mpd/home.nsf/Glossary

* An instrument that measures the characteristics of light that is either reflected from or transmitted through an object.
www.inkcartridgesworld.com/_glossary.html

* An instrument used to measure the amount of light reflected from a specimen when illuminated by a controlled light source. This measurement generates a spectral curve (fingerprint) of a product, which can be used in the numerical identification and the calculation of color difference between samples.
www.chromacolors.com/glossary/index.php

* a photometer for comparing two light radiations wavelength by wavelength
wordnet.princeton.edu/perl/webwn

* In physics, spectrophotometry is the quantitative study of spectra. It is more specific than the general term electromagnetic spectroscopy in that spectrophotometry deals with visible light, near-ultraviolet, and near-infrared. Also, the term does not cover time-resolved spectroscopic techniques.
en.wikipedia.org/wiki/Spectrophotometer

Answer 3

spec·tro·pho·tom·e·ter (spktr-f-tm-tr) Pronunciation Key
n.
An instrument used to determine the intensity of various wavelengths in a spectrum of light

Answer 4

An instrument used to measure the intensity of electromagnetic radiation at different wavelengths

Answer 5

hope this helps

http://en.wikipedia.org/wiki/Spectrophotometer