Near-Infrared Questions for Light Experts?
913461
"Near Infra-Red" starts at 750nm wavelength (a fixed, accepted value).\nIn theory, and by definition, we CAN'T see it.\nHowever, we are all different: we are not machines built on a standard.\nTo find out if you can see NIR, you have to go to a laboratory, ask for a calibrated source of light and check from say, 650nm to 900nm wavelength radiations.  You will then be able to find exactly your limit for "your" visible.  If it is above 750nm, then you see NIR... officially!\nYou can compare this to your auditive perception: the AF (audio frequencies range, by definition, from 16Hz to 16000 Hz).\nMany of us cannot hear 16kHz, many of us can hear much higher than that!\nIt is all relative.
1120719
CCDs are naturally sensitive out to about 1000 nm (nanometers), while the human eye can't see much past 760 nm. CCD cameras have infrared blocking filters, but some of them still let a fair amount of infrared in. A quick test of whether your camera is infrared sensitive is to point your TV remote at it and push a button. If it's sensitive, you'll see the IR LED light up in the LCD viewer.\n\nA CCD camera uses red, green, and blue filtered pixels to form a color image. Infrared looks white because apparently all of these pixel filters let IR through.
462356
It probably requires a mass spec technique.  Infrared might work.  Your detection level will be the problem.
890524
Red = 625 to 760 nm\nOrange = 585 to 620 nm\nYellow = 565 to 590 nm\nGreen = 520 to 570 nm\nBlue = 440 to 490 nm\nIndigo = 420 to 440 nm\nViolet = 380 to 420 nm\n\nThese are approximate wavelengths for the visible spectrum in nanometers (notice how some values overlap). Taken from Wikipedia.
832832
Techno Alan is wrong. The glass does absolutely nothing to shift the infrared to the visible spectrum.  What is does is absorb some of the visible light while allowing the near infrared to pass through.  Photographic film can be made to respond to the near infrared, meaning that just as some of the layers in the film get exposed by the red , green or blue, an IR film has a layer that is also sensitive to the near IR.  So all that the filter does is to supress the visible part of the scene relative to the near IR.\n\nMost digital cameras include a infrared and UV filter over the sensor.  The filter prevents near infared light from adding noise to the red pixels in the camera array, and at the same time prevents you from taking the IR picture.  The UV filtering prevents the "fogging" that can occur on bright days from UV background. It eliminates the need for the "skylight filter" that is frequently used in film photography to enhance contrast.\n\nNow to the original question - to see in the infrared you need to use a sensor that can detect infared light and then convert it to a visual image.  Night vision goggles use a layer of material that emits an electron when it absorbs a near infrared photon.  The eletrons are "multiplied" uisng a "microchannel plate".  The stream of electrons then strikes a phosphor screen, making a visible image.  \n\nAt longer infared wavelengths different detector materials are used.  The materials can be either photoconductive (absorbed light changes the conductivity of the material which can be electrically read out) of photovoltaic (absorbed light generates electric charges - electrons and hoels-  within the semiconductor marterial that are collected and read out).  (CCDs or CMOS sensors in digital cameras are photovoltaic imaging devices that are sensitive to visible light).  There are also "bolometer" thermal sensors that absorb infared light, generatyinga  small change temperature can be read out to form an image.
254375
Great question!\n\nThe human eye and the real world have a range of light and dark values from 100,000 to 1.\n\nMedia like film and digital cameras have traditionally only been able to capture or show about 500 to 1 in ranges.\n\nThe next generation of digital cameras will compete on pixel quality and range sensitivity, not just megapixels.\n\nSee the cool links below:
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Sierra Pacific Infrared\n\nhttp://www.x20.org/
617450
Some molecules absorb visible light, e.g. due to conjugation and pi to pi antibonding transitions, with the highest intensity at a particular wavelength.  One can prepare standard solutions, with accurately devised known concentrations, the measured intensities of these solutions are correlated with these standard solutions, covering a particular dynamic range.  Assuming Beer's Law, the plot will resemble a linear curve, and a least fit regression line and its equation can be obtained; also by correcting for the blank if this is has not bee accounted for by the spectrometer.  The unknown pure solution, or a matrix derived alternative method if the solution is not pure that there are significant impurities in the unknown solution, will also be measured at this wavelength and it's intensity, often the y value, will be plugged into the regression equation to estimate the concentration.
373528
Yes I work for the institute of color technologies. We need to figure out everyones favortie color in the entire universe.(including aliens) can you help?
906177
compound light microscope
759217
Burn it in a sprectrophotometer.  Look at the emitted light.
190902
As usual, howstuffworks has great illustrations and description of how things work, including LED's.  High intensity LED's use the same principles but supply greater light flux (and perhaps focus it better too).  Good luck.
895656
Hi. You could start here : http://www.mellesgriot.com/products/optics/oc_3.htm\nMay not be the best for everyone.
750681
A photon with a wavelength of about 650 nm
55652
light density or intensity? if you're talking about intensity then it depends on distance. that's an inverse square relationship.
545100
As no one else has had a crack at this, I'll have a go with my best guess. Have you access to a reflectance spectrophotometer? Instead of shining light through a sample, it measures light reflected from a sample. At a pinch, you might be able to modify a uv/vis spectrophotometer to measure this.\n\nI hope this helps.
1081043
Wavelengths slightly longer than red light are in the "near infrared" region of the electromagnetic spectrum.