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Glasses which enable you to see in black & white

by SAZAR
Tags: black, enable, glasses, white
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SAZAR
#1
Mar11-09, 03:35 PM
P: 209
Out of curiosity:
Is there a transparent material or coating or a combination of the two (or something similar) which lets you see through it and see things around you in pure black and white?


:) I thought it would be kind of cool... Dalton(ism) glasses. Hah!

(of course electronic-viewfinder-type equipment is not an answer to this question, only genuine "see-troughs" are the theme)
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mgb_phys
#2
Mar11-09, 03:45 PM
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Any monochromatic filter would let you see in monochrome, of course it would be black and whatever_color rather than black and white.
Magenta filters used to be popular for this because they approximately averaged the peak response of film to the response you eye.
SAZAR
#3
Mar11-09, 04:08 PM
P: 209
Yea', it came to my mind before, but that's not it.

I don't know how, be imaginative...
Example:
I thought - if light is actually absorbed and re-emitted by the atoms of the transparent material (rather than just passed through), then I thought maybe there is a way for some special coating or material/combination to re-emit other wave-lengths along with the incoming wavelength converting the energy from incoming light into compensating wave-lengths, so everything is balanced to white light (combination of all wave-lengths)... or something.

mgb_phys
#4
Mar11-09, 04:13 PM
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Glasses which enable you to see in black & white

Well the wavelength it emmitted would have to be longer (ie redder) than all the wavelengths it absorbed because shorter wavelengths have more energy and so you can't absorb a low energy red photon and emit a high energy blue one.
Then there is the problem of direction - a ray coming into the glasses at a particular angle would be remitted in all directions by the dye.

What you could do is use a micro-channel plate (imagine a microscopic version of looking down the length of a stack of pipes) to only allow photons from a particular direction through and coat the insides of the tubes with a florescent dye
SAZAR
#5
Mar12-09, 04:40 PM
P: 209
What effect would be observed if someone watched trough glasses which are coated with reflective layers so close that interference happens if light is right?
(something like in lasers - light of precise wavelength and polarization interfering when going back and forth between semi-transparent mirrors)
mgb_phys
#6
Mar12-09, 04:56 PM
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That's how you make a single wavelength (narrow band) filter - so would just see black and that-color
SAZAR
#7
Mar12-09, 05:19 PM
P: 209
Does that mean those filters aren't dyed at all???

---

...I guess it's impossible to make black & white stuff. But the effect would be really awkward and impressive - imagine taking it in and out of your line of sight: color, b&w, color, b&w... :D It's like all of the sudden entering the world of some old black & white movie... Ahhh... :)
LOOK THERE'S HUMPHREY BOGART!! 8.
mgb_phys
#8
Mar12-09, 05:43 PM
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Quote Quote by SAZAR View Post
Does that mean those filters aren't dyed at all???
Broad band filters are dyes.
Narrow band are usually interference but with a dye layer as well because a 800nm transmission filter would also pass 400nm unless you blocked it with a dye (or used a glass that was opaque at 400nm)
SAZAR
#9
Mar20-09, 09:12 AM
P: 209
Could we coat eye-glasses with multitude of semi-transparent layers spaced to some wavelength we count on so that they increase light to a point that one can see like in broad daylight in very dark conditions.
Or to have a flashlight working on a similar principle?
------

PS:
What's the so 'great deal' about laser light?
I read some info about coherence and it's all inconclusive to me.
Why light used for cutting has to be (or it's preferred at least) laser light - why couldn't it be incoherent ordinary light? How much times can laser possibly increase the outgoing light (what - double... triple...)?

The only thing I can think of is that laser adds energy of one portion of length of light wave to the incoming part - but the same energy comes out interfered or not - it accumulates in material absorbing it - right (maybe that time interval when laser turns on to the time it reflects and interferes and then exits is crucial - but - that's nanoseconds - right? how much energy can that gain... maybe I'm missing the point completely...)

I always thought that the point is in increasing the intensity of the light by adding amplitudes to an even greater amplitude, but is it then possible to put more semi-transparent layers to make even greater than greater amplitude? I mean - you can't create something from nothing - you can't gain more energy from light than it gives already - right, you can only concentrate it over time with interference?
mgb_phys
#10
Mar20-09, 10:19 AM
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Quote Quote by SAZAR View Post
Could we coat eye-glasses with multitude of semi-transparent layers spaced to some wavelength we count on so that they increase light to a point that one can see like in broad daylight in very dark conditions.
You can't make energy out of nothing - if it's dark there simply aren't many light photons around. All you can do is detect the small amount of light and generate a larger level (like night vision goggles - but the extra power comes from batteries)

What's the so 'great deal' about laser light?
You can produce a lot of monochromatic light in one place cheaply. The amount is pretty much only limited by how much electrical power you supply.

I read some info about coherence and it's all inconclusive to me.
Why light used for cutting has to be (or it's preferred at least) laser light - why couldn't it be incoherent ordinary light? How much times can laser possibly increase the outgoing light
It doesn't need to be coherent - almost no laser applications (other than physics experiemnts) need coherence.

Remember melting plastic toy soldiers with a magnifying glass and the sun - daylight is not coherent.
The problem is that the amount of power from a thermal source (ie any source of light that isn't a laser - like a light bulb) depends on the size and temperature. You can't just turn up the electricity on a light bulb and get more light.
You can heat the filament more but it will soon melt. You can make the source bigger but then you need larger optics to concentrate the light to a point.
The nice thing about a laser beam is that the light is already pretty concentrated, it is one color so the optics so concentrate it further are simple and if you want more power - just turn up the electricity - or add more lasers together.

I always thought that the point is in increasing the intensity of the light by adding amplitudes to an even greater amplitude, but is it then possible to put more semi-transparent layers to make even greater than greater amplitude? I mean - you can't create something from nothing - you can't gain more energy from light than it gives already - right, you can only concentrate it over time with interference?
Power is the number of photons. Photons with shorter wavelengths have more energy, so for the same number of photons/second a visible laser would have more power than an infrared one and a UV laser even more power.
For engineering reasons - it's easier to make high power gas lasers, most cutting laser are CO2 at 10.6um in the far infrared. The individual photons are very weak compared to visible light but there are a lot of them in a 10Kw laser!
Now with high powered semiconductor diodes it is possible to make cutting lasers that use visible light.

For cutting applications the photons don't have to be in pahse or coherent it is purely an energy->heat material-> material evaporates process.
SAZAR
#11
Mar20-09, 10:38 AM
P: 209
Quote Quote by mgb_phys View Post
The nice thing about a laser beam is that the light is already pretty concentrated, it is one color so the optics (so concentrate it further) are simple and if you want more power - just turn up the electricity - or add more lasers together.

What, does it mean then you can put a 9V battery (or stronger) to a simple 4.5V laser pointer (the one which works on three button batteries) and make things melt when hit with its laser light?
mgb_phys
#12
Mar20-09, 10:49 AM
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No - it means for a diode laser you can use a single 3v*100mA diode and get X amount of optical power, you can package a pair of them together and supply 200mA and get 2X of power until you get to arrays with a few KW of power.

With a gas laser it is controlled by how much power you put into the pumping flashlamp, how many you have and how often you flash them.
Benedict42
#13
Apr17-11, 08:18 PM
P: 1
In case anyone's still interested: http://adsabs.harvard.edu/full/1919ApJ....49..237F
todbr
#14
May3-11, 01:36 PM
P: 1
I would be REALLY interested in a black and white pair of glasses. In fact, I'm curious why it's not something more easily available - it'd be so useful for drawing, cinema, and all kinds of visual arts.
If I understood correctly, you can't do it solely with filters, it'd have to be something like a night vision goggle, which involves digital processing, right? These goggle are rather cumbersome to wear, they're not like normal glasses... Strange how it's something so simple to do chemically (i.e., black and white film) but hard physically (glasses)...
I've googled a bit but found nothing of this kind of thing for sale, if someone does, please drop me a message. I'm really hooked up in 20's-40's films, so it's simply incredible imagining it'd be like an old movie, but for real...
Mech_Engineer
#15
May3-11, 03:00 PM
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Quote Quote by todbr View Post
I would be REALLY interested in a black and white pair of glasses. In fact, I'm curious why it's not something more easily available - it'd be so useful for drawing, cinema, and all kinds of visual arts.
If I understood correctly, you can't do it solely with filters, it'd have to be something like a night vision goggle, which involves digital processing, right? These goggle are rather cumbersome to wear, they're not like normal glasses...
You have to understand what your eye perceives as "white" and "black." White is the presence of all colors of the spectrum, so to "convert" a color to white you need to add all of the other colors to it. This obviously can't be achieved with a simple filter. It is possible to take a monochrome image through a colored filter (black and single color), but you can't convert it to black and white.

A black and white picture is the measurement of one thing- the presence of light (in any portion of the visible spectrum). The presence of any color is white (of a pre-determined brightness), no color (light) is black, anything in between is a shade of gray.

Quote Quote by GregMartin View Post
Strange how it's something so simple to do chemically (i.e., black and white film) but hard physically (glasses)...
It isn't all that strange, measuring the presence of light regardless of color is easy compared to measuring the presence of specific wavelengths of light.
turbo
#16
May3-11, 03:15 PM
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I don't remember the name of the device, but there was a tool (used as a monocular on a neck-lanyard mostly) that old-time movie directors used to use to approximate the light/contrast levels that would be recorded on their B&W movie film. It must have been somewhat useful, though it would take some experience to gauge what the cameras were capturing.

Edit: It's called a director's viewfinder, and they were used to help directors find places to mount their heavy cameras. Maybe not so much for B&W films as I had (potentially mis-) remembered. For some reason I thought they featured monochromatic filters, though. Remember all those old movies and TV shows with "moonlight" scenes that were obviously shot in broad daylight?
lifeson22
#17
May19-11, 01:45 AM
P: 20
Yes - any glass made before 1951 in the televsion market. By going even farther in time you can also make it mute.
johnbbahm
#18
Jun8-11, 10:42 AM
P: 143
I remember seeing a pair of dual polarized glasses in one of my labs. Each eye had two polarized lenses, one fixed and one that would rotate. As I recall as you got close to the 90 degrees out of phase, Things got very dark, but also most of the color went away.
This would be easy to try with two pair of polarized sun glasses.


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