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Discussion Starter · #1 ·
If the scan-line unit can block out certain wavelengths (and thus only project a single color), why can't they operate using white lamps? White light is composed of RGB, so if you wanted B, you could block out all wavelengths except for visible blue light, right?


I'm missing something here, aren't I. :eek:
 

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"If the scan-line unit can block out certain wavelengths..."


Not sure what the heck you're referring to, but the GLV uses no blocking filters. It has separate red, blue, and green lasers shining on the GLV device or devices; I forget if there are one or three of them. In any case the proportion of R/G/B is determined by modulation of the tiny fingers making up each pixel.
 

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GLV have a much lower etendue (acceptance angle * area of device) than other display devices. The light from white sources (even arc lamps) cannot be completely imaged onto GLVs. Only lasers have a low enough etendue to be a suitable illuminator.
 

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GLV device has a single (very narrow) column of pixels. Only lasers can produce a small enough beam to cast most of its energy on the pixels without wasting most of it.


Now that I think about it, I wonder how they spread the light over the height of the column of pixels.
 

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Since GLV uses a single row of pixels, I assume it would use a rotating mirror to deflect the laser beams.


This is a commonly used technique, and so is well understood and easy and cheap to accomplish.


This works with laser beams, but I can't imagine it would work with any other light source.


anyway, lasers would be more efficient, since you aren't needing to filter out the light you aren't using.


On the other hand,being monochrome, the red, green, and blue can't possibly be close to the standard R, G, B values.

I wonder how much that changes the look.

Too bad you can't make use of the wider color space the lasers give you (because the video signal already assumes standard R, G, B, and colors outside that gamut are already lost).
 

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Chuck,


I know that a scanning mirror sweeps each pixel across the screen to make a row; what I wonder is how is the column illuminated.


"On the other hand,being monochrome, the red, green, and blue can't possibly be close to the standard R, G, B values."


There was a laser pj demo'd in Europe IIRC and forum members said the colors were incredibly good.
 

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Quote:
Originally posted by Chuck_McDevitt
On the other hand,being monochrome, the red, green, and blue can't possibly be close to the standard R, G, B values.
The three guns of a CRT are each monochrome. Monochrome means one color. The color of many CRT units is well known to be quite good. Likewise, many DLP units have excellent color and are only able to alter the colors by mixing the three primary colors and altering their intensity.


Perhaps you are suggesting that the colors may not be the exact same as the colors that are expected, such as perhaps if the blue from a laser isn't the same shade of blue from a CRT. While this is certainly a possibility, I would think that they have been designed to send out the appropriate frequency of light. I can't imagine they would have tried this with pastel lasers.
 

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Guess the size.weight and power needed for the first ht glv projector. While you are at it guess the year of intruduction of GLV for ht use.


My bet is on 2007 for a ht GLV-projector.
 

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Discussion Starter · #11 ·
Quote:
Originally posted by Mr.Poindexter
The three guns of a CRT are each monochrome. Monochrome means one color. The color of many CRT units is well known to be quite good. Likewise, many DLP units have excellent color and are only able to alter the colors by mixing the three primary colors and altering their intensity.


Perhaps you are suggesting that the colors may not be the exact same as the colors that are expected, such as perhaps if the blue from a laser isn't the same shade of blue from a CRT. While this is certainly a possibility, I would think that they have been designed to send out the appropriate frequency of light. I can't imagine they would have tried this with pastel lasers.
Actually, the "guns" of a CRT fire electrons. The electrons light up phosphors on the screen, which emit a single wavelength of light when energized by the rays.
 

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I am pretty sure that crt phosphor does not have a single frequenccy response to electron bombardment. Why then would crt lenses need color filtered output?


Also crt is not the norm life is !!!
 

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Quote:
Originally posted by MrHelpful
If the scan-line unit can block out certain wavelengths (and thus only project a single color), why can't they operate using white lamps? White light is composed of RGB, so if you wanted B, you could block out all wavelengths except for visible blue light, right?


I'm missing something here, aren't I. :eek:
MrHelpful,


GLVs work by diffraction.


However, the GLV forms a pattern that diffracts the incoming light. However, the proper pattern depends on the wavelength

of the light. Since wavelength is inversely proportional to frequency, i.e. color - the pattern that works for diffracting

one color won't work to diffract others.


A laser is a single frequency, i.e. wavelength device. The GLV forms the requisite diffraction pattern for the particular

wavelength of the laser that is illuminating it.


That's why you need a laser, and can't use white light.
 
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