Talk:Optical spectrometer

confusion surrounding the term

The confusion surrounding the term spectrometer is not Wikipedia's fault, but we do need to sort it out.

See [1], [2], [3], [4], [5], [6] for some conflicting definitions.

Work in progress. Ultimately, we need to combine several articles and disambiguate others, so all the accepted usages are clearly explained and so readers of all backgrounds can easily get the information they want. Andrewa 20:09, 1 Dec 2003 (UTC)

See also for some history and other background:

• xray spectrometers
• gamma ray spectroscopy
• spectrometers for use with accelerators
• the making of the spectroscope workshop
• awesome slideshow on history of stellar spectroscopy
• classical spectroscopy
• another course in history of spectroscopy
• product description of spectrometer for measuring thickness

I'll incorporate these links and material as I get time... or feel free! Andrewa 07:00, 2 Dec 2003 (UTC)

The IUPAC Gold Book gives the following definitions.

spectroscope A device which enables visual observation and evaluation of optical spectra (usually confined to the visible spectral region)

spectrograph A combination of a spectral apparatus and a camera, which enables an image of a spectrum to be recorded. Spectra are recorded by a photographic emulsion or other means, e.g. two-dimensional electronic image sensors.

spectrometer A general term for describing a combination of spectral apparatus with one or more detectors to measure the intensity of one or more spectral bands.

These IUPAC definitions are preferable to those provided by dictionaries. If there is another major professional organization that defines these terms differently, then further discussion is warranted. Most modern instruments are spectrometers, and spectrometers are not really spectroscopes or spectrographs. A monochromator is not a spectroscope, but it can be part of a spectrometer. A spectrograph produces spectrographic plates, which are not the same as the intensity/transmission/absorbance vs frequency/wavelength plots that are produced by a spectrometer. Cfn137 (talk) 02:18, 8 September 2009 (UTC)

As I was tought in the school the 1970:ies, X-scopes allowed a general view of X, X-meters also had a numeric scale allowing quantitative measurements of X, and X-graphs produced graphs or still images in any way providing the means to read both values, variations and trends. But that was in Sweden, if that makes a difference... ... said: Rursus (^mbork³) 18:52, 25 November 2009 (UTC)

Blackbody

The article says:

When a material is heated to incandescence it emits light that is characteristic of the atomic makeup of the material.

Shouldn't blackbody radiation be mentioned on this place? --Abdull 5 July 2005 15:14 (UTC)

Everything with any non zero temperature emits blackbody radiation. To the first order, blackbody radiation is independent of the material. --150.203.177.218 06:44, 10 October 2006 (UTC)

The article is alluding to atomic emission lines. The energy of an emission line (which has a reciprocal relation to wavelength or color in the visible range) is related to the differences in the quantum energy levels of the electrons that emit the photons in question.

Incandescent objects usually do emit something like a blackbody spectrum, in fact we speak of the color temperature of a source, the temperature of the blackbody that would emit such a spectrum.

So I think that using the term incandescence to describe the origin of the phenomenon confuses the issue, it ought to be changed. The emission lines are real though, and important.

AJim 04:06, 27 May 2007 (UTC)

Fraunhofer or Kirchhoff/Bunsen?

The Joseph von Fraunhofer page describes him as the inventor of the spectroscope. A search for spectrosocope redirects to spectrometer which is said to have been invented by Kirchhoff and Bunsen. No doubt relates to the confusion over the term spectrometer as described below by Andrewa.

—The preceding unsigned comment was added by 59.92.140.254 (talk • contribs) .

Rearding the first sentence

, please note that a spectrometer is not necessarily a optical device!!. For example, s nuclear spectrometer uses no optics. Someone, other than me, could fix that. :)

I agree, and will make the change. Cfn137 (talk) 02:18, 8 September 2009 (UTC)

Regarding the first paragraph -last sentence

.. radio and audio? audio isn't part of the EM spectrum.. is this true, does it need clarifying?

I agree, I removed it. —Preceding unsigned comment added by 82.233.216.159 (talk) 21:54, 12 December 2007 (UTC)

Build Your Own

This is an important article, that many other articles need to refer to -- and it needs a lot of work. We need an article about just optic applications, either this one or some other -- all the acoustic etc other uses need to be separated. We need lots of illustrations, some in color -- let's start with the ones from the Spectroscopy article.

Although the fancy versions of these instruments can cost thousands of dollars, let's also emphasize that any prism or diffraction grating can manifest these behaviors, and they are all around us, even the surface of a CD. Edmund Scientific offers a variety of Spectrometers and Spectroscopes in their Light Analysis category for $1-50. They also offer info on:

• Build Your Own Grating Spectroscope
• How Diffraction Gratings Work [7]

These are interesting resources:

• Supplement: Build Yourself a Simple Hand-Held Spectrograph good sample spectra
• SPECTROSCOPY FOR THE SCHOOL build a simple spectroscope from a CD

-69.87.199.97 11:26, 26 May 2007 (UTC)

• How to design a spectroscope
• A CD spectrometer

"A simple spectrometer can be built from a CD and a box. Cut a slit on one side of the box. Place the CD on the other side with about 60 degree angle. Look down into the openning on the box. The slit should not be too wide, otherwise the spectrum lines will be blurred. It should not be too narrow either, otherwise the spectrum is too dim. I use a 0.2mm wide slit."
Spectrographs of common light sources

• CD spectrometer CD + cardboard tube or cereal box
• [8] Great construction photos, razor-blade slit
• [9] "MiniSpectroscopy displays a visual representation (a "spectroscope view") of a sample spectrum simultaneously with a graphical (intensity vs. wavelength) representation. Students draw or redraw the graph using the computer mouse, and the corresponding "spectroscope view" appears or changes immediately as they draw, changing just as changes are made in the graph. This immediate feedback gives students a kinesthetic connection between making the graph and viewing the spectrum being represented."
• Mini Spectroscopes "You can make a spectroscope to allow you to separate the colors of light..."
• How to work with the spectroscope : a manual of practical manipulation with spectroscopes of all kinds 1882;

Browning, John (1835-1925) NOT_IN_COPYRIGHT - online full-text download -69.87.204.146 16:17, 26 May 2007 (UTC)

It is indeed easy to build a simple device, although the CD device described is more like a spectrograph than a spectrometer. The problems begin when you attempt to make quantitative measurements, which is what the term spectrometer implies. It is quite difficult to build an instrument where measurements will obey the Beer-Lambert law over more than a small range of absorbance, for instance, especially when high spectral resolution in needed at the same time. The monochromator article tries to explain some of the difficulties and the range of devices for the optical range. There is an big difference between even a simple .1m single monochromator instrument and a .4m double monochromator instrument for use in analytical chemistry. There is an even bigger difference between these and a 2m double monochromator astronomical instrument. The relative prices of such instruments reflect that difference.

AJim 04:27, 27 May 2007 (UTC)

When one builds a simple CD, DVD, or other cheap diffraction grating/hologram-based device, the usable frequency response is normally limited by the human eye looking at the output, or the ordinary camera recording the picture. But, what are the inherent limits of these simple devices? How flat in the visible? How far into the UV/IR, how flat? And what simple/cheap detectors, multi-element (CCD etc) or single element (mechanically scannable) would have usable response into the UV/IR bands? And is there a simple/cheap way to use film etc to record the bands? This must have been important, decades ago? Links to detailed info about how it was done, and most practical ways to do now?-69.87.203.17 21:15, 27 May 2007 (UTC)

equal-area power graphs?

Standard optical power spectrum plots are spaced equal-nm on the X axis. The Y axis is some unit of power (if one is lucky enough to have calibrated data). Does this result in equal-area power graphs? If not, is there a standard way to distort the X or Y axis to obtain equal-area power graphs, and if so, what are such plots called. (In other words, what we want is a graph that shows visually, vividly, obviously, what portion (half?) of the sun's radiation is in the visible spectrum, for example. Are the plots in the Solar radiation article properly conveying such info?)-69.87.203.17 21:25, 27 May 2007 (UTC)

Adding Links to my website =

I've noticed that somebody has been adding links to my spectroscopy website and somebody later removes them. For the information of both the adder and remover: When you add a link to my website, include my full name and specifics on what the website is added for. When you remove a link, keep in mind that I am not the one who adds the links. I have published links from my website to certain articles/sections, but I always sign with my name.

This idiocy must stop sometime. Galidakis 16:59, 4 June 2007 (UTC)

White light and rainbows?

I just removed the following line from the beginning of the article:

Simply, it turns white light into rainbow and vice versa.

It appears to me to be completely out of context and an outright wrong description (or at best a deceptively gross oversimplification) for most things that could be called a spectrometer (going by this sentence one would think there's no difference between a spectrometer and a simple prism, ignoring the fact that many spectrometers don't even deal with "white light", or even light at all) -- Foogod (talk) 20:40, 21 January 2008 (UTC)

Is a spectropolarimeter a spectrometer?

The current introductory paragraph currently states:

The variable measured is most often the light's intensity but could also, for instance, be the polarization state.

Measuring polarization as a function of wavelength/frequency is spectropolarimetry, and the device used is a spectropolarimeter. I don't think this device should be called a spectrometer, but I don't heavily object either. However this sentence dilutes the introduction, and spectropolarimetry is not mentioned later.

If it solely measures the polarization per wavelength, then it is not a spectrometer. ... said: Rursus (^mbork³) 18:55, 25 November 2009 (UTC)

Wavelength vs Frequency

I'm not sure how one can state a preference for wavelength over frequency with a neutral point of view. Furthermore, the standard independent variable in NMR spectroscopy is chemical shift. It is also disputable whether nanometers is the most common measurement of wavelength, since in the infrared the preferred unit would be micrometers. Angstroms is also commonly used, especially in older literature. It is probably better to focus on energy, frequency, vacuum wavenumber, and temperature as being proportional.

• It would probably be better to have a separate article that includes this about terms in the scientific community, as this would ameliorate the discrepancies and thus make the information on many pages more accessible intellectually. As a scientist, one gets a sense of scale for these things and an understanding of the relationships therein as part of the reading process, but for non-scientists this is very likely not the case. It would be both a selfish crime and great disservice to the profession to withold this understanding from the public - even if they don't have a fluent working knowledge of the systems, why not elucidate for them?

Wrong wavenumber axis in the first comparison

In the first scale comparison "A comparison of the three abscissa types typically used for visible spectrometers.", the wavenumber scale is obviously wrong, since wavenumber is proportional to energy and inversely proportional to wavelength.