Is it possible to magnify light heat?

[Dakota]

Is it possible for me to make a flash light into a "laser" hot enough to burn through paper. Here is what I have: a light prism, 2 light splitters,(the can separate light so it goes 2 ways) 2 magnifying glasses, and a microscope.(I don't want to use it though) If there is any thing else you think I might have let me know. After you explain how to make it(if possible) can you explain why it works,... or why it doesn't. Thank in advance.

 

[ZapperZ]

A huge portion of "light heat" (to use the phrase you adopted) is in the IR part of the spectrum. How much do you think this part of the spectrum is attenuated by all the optical elements that you intend to use?

Zz.

 

[russ_watters]

In principle yes, in practice you will need something much stronger than a battery operated flashlight.

 

[rootone]

You can certainly burn paper using just the Sun and a simple magnifying glass.

 

[Nidum]

https://en.wikipedia.org/wiki/Burning_glass

https://en.wikipedia.org/wiki/Solar_furnace

 

[Dakota]

In principle yes, in practice you will need something much stronger than a battery operated flashlight.

You can certainly burn paper using just the Sun and a simple magnifying glass.

I know but I want to do is with a flash light in a dark room.

 

[mfb]

You can certainly burn paper using just the Sun and a simple magnifying glass.

Sunlight is more intense and better to focus than your typical flashlight.

With sunlight and a magnifying glass with a diameter of 5 cm, you get ~2 W with a focal point of ~1 mm diameter. A bright flashlight might have that as total power output, but good luck focusing it to such a small spot. You won't be able to focus it better than the size of the emitter.

 

[Dakota]

A huge portion of "light heat" (to use the phrase you adopted) is in the IR part of the spectrum. How much do you think this part of the spectrum is attenuated by all the optical elements that you intend to use?

Zz.

I don't know I was hoping one of you could tell me. So far

Sunlight is more intense and better to focus than your typical flashlight.

• With sunlight and a magnifying glass with a diameter of 5 cm, you get ~2 W with a focal point of ~1 mm diameter. A bright flashlight might have that as total power output, but good luck focusing it to such a small spot. You won't be able to focus it better than the size of the emitter.

So I can't do it? What about a light house, how do the make the lights so bright? If I could magnify the light in a similar way, I could buy a big magnifying glass. or Could I use a laser pointer, the emitter will be tiny.

 

[mfb]

So I can't do it?

There are probably flashlights with sufficient power. But where is the point? A proper laser (typical laser pointers won't have sufficient power I think) can do the same and doesn't need additional optics. And why does it have to be light to ignite paper?

What about a light house, how do the make the lights so bright?

They don't use a battery-operated flashlight? They do not magnify light, they just use a much more powerful light source.

 

[Dakota]

A huge portion of "light heat" (to use the phrase you adopted) is in the IR part of the spectrum. How much do you think this part of the spectrum is attenuated by all the optical elements that you intend to use?

Zz.

what do you "attenuated"

There are probably flashlights with sufficient power. But where is the point? A proper laser (typical laser pointers won't have sufficient power I think) can do the same and doesn't need additional optics. And why does it have to be light to ignite paper?
They don't use a battery-operated flashlight? They do not magnify light, they just use a much more powerful light source.

The first light house was one of the 7 wonders, it used a fire for the light source. It was as tall as a 44 story building, so they would have had to magnify it some how. Can you explain how this works?

 

[Dakota]

There are probably flashlights with sufficient power. But where is the point? A proper laser (typical laser pointers won't have sufficient power I think) can do the same and doesn't need additional optics. And why does it have to be light to ignite paper?
They don't use a battery-operated flashlight? They do not magnify light, they just use a much more powerful light source.

The reason I'm going through all this is because my science teacher said he would give extra points to anyone who can make a laser. To get into Harvard you have to have a GPA of at least 4.04.

 

[davenn]

The reason I'm going through all this is because my science teacher said he would give extra points to anyone who can make a laser. To get into Harvard you have to have a GPA of at least 4.04.

I don't think you understand the difference between a normal light source and a laser light source
and it seems all the posters above missed your laser comment in your first post as they didn't address it

Tell me what you know about the difference between a normal light and a laser light source

you are not going to make a laser light source at home ... as in modifying a torch or other lamp
but you can buy a laser light source eg a laser diode and build up the electronics circuit around it to make it work
ohhh and you will need some optics as well

Dave

 

[Dakota]

I don't have any way to see invisible light, is there something I can download on my phone. How could I build up electrons around the laser circuit? (what does eg mean)

I thought a laser was a pinpointed light. Thanks for the help. (and actually reading my question)

 

[davenn]

I don't have any way to see invisible light,

? invisible light hasn't entered the conversation till now
Tho you hinted at it with your oddly worded thread title
IR ( Infra-red) light is invisible to us commonly used for remote controls

How could I build up electrons around the laser circuit? (what does eg mean)

electronics, not electrons. If you haven't done any electronics construction, then it may be a project out of your grasp at the moment till you learn a bit more

here is an example of a laser diode ...
the gold coloured bit is about 1cm in diameter

I thought a laser was a pinpointed light.

no, that isn't the definition
did you know the word LASER is an acronym ? ... that is, each letter stands for something

Light Amplification by the Stimulated Emission of Radiation ... the radiation in this case being IR or visible light

google " what is a laser?" and see what you come up with
then come back with any question on things you read and didn't understand

we are here to help you learn

cheers
Dave

 

[mfb]

The first light house was one of the 7 wonders, it used a fire for the light source. It was as tall as a 44 story building, so they would have had to magnify it some how. Can you explain how this works?

They did not magnify it. They just used a large fire.

The reason I'm going through all this is because my science teacher said he would give extra points to anyone who can make a laser.

A laser works completely differently from all the other light sources discussed here. You cannot use the light of any of them to "make a laser". You have to start completely differently if you want to actually make a laser.
Start by reading what a laser is.

I don't have any way to see invisible light, is there something I can download on my phone.

The phone might be able to detect strong infrared light, and probably display it as red.

 

[russ_watters]

I don't think you understand the difference between a normal light source and a laser light source
and it seems all the posters above missed your laser comment in your first post as they didn't address it

I ignored it because "laser" was in quotes, which implied to me that the OP knew that what would be created wouldn't really be a laser. Unfortunately, I was not correct...

 

[Vanadium 50]

There is a lot of confusion and changing of direction in this thread (the most absurd of which is probably that you need a 4.04 GPA to get to Harvard) but the original question has an answer: the absolute best you can do is to have an image on the paper that is the same size and temperature as the filament of the light bulb. That is probably not enough to ignite a sheet of paper.

 

[CWatters]

he would give extra points to anyone who can make a laser

That's quite a challenge and nothing in your original post would count as making a laser.

Youtube has a series on making a DIY C02 laser...

and a ruby laser..


Note it would be dangerous to build and operate one of these without taking appropriate safety precautions.

Edit: At one point in the follow up video he states that the peak power going into his pulsed ruby laser is 4 Mega Watts supplied by a bank of capacitors charged to 6-8kV. Perhaps there are easier ways to improve your grades :-)

 

[mfb]

Note it would be dangerous to build and operate one of these without taking appropriate safety precautions.

Especially for (but not limited to) the CO2 laser, as you don't see the infrared beam easily.
Electrical dangers are there for both.

 

[Dakota]

Thank you all, I talked to my science teacher, and he agreed with me that this is too hard, and because I was the one to bring it to his attention, I still got the extra credit. (that doesn't mean I won't try to make one still)

 

[houlahound]

May I suggest a simple match to burn paper.

 

[Dakota]

I needed a laser.

 

[f95toli]

I needed a laser.

Was it your teacher who brought up "burning papers"? If so he/she is being very irresponsible. Any form of laser (or other form of lightsource) that can burn paper will also be strong enough to make you go blind. The power output of a good quality laser pointer will be so low that they are generally safe, especially since they emit visible light.

However, there are plenty of places on the internet where you can buy lasers which output WAY to much power for them to be safe (this includes many cheap laser pointers). Note also that the power rating is only part of the issue, even a relatively weak laser can severely damage your eyes if it emits non-visible light since it won't activate they eye's blink reflex (which is our primary defense).

 

[Merlin3189]

... the absolute best you can do is to have an image on the paper that is the same size and temperature as the filament of the light bulb. ...

I can't argue about the temperature (brightness?), but why can't I make a smaller image by having the source further from the lens than the image?
I've seen this point made elsewhere and been puzzled by it. So I assume it simply means that you can't make an image that is at the same time both smaller and brighter. So is the point that having the image the same size as the object gives the maximum brightness? (Cf. the maximum power transfer theorem in electric circuits?) If you move the lens further away, to get a smaller image, you capture less light, but if you move the lens closer to capture more light, you get a bigger image and spread the power over a larger area.

 

[mfb]

I can't argue about the temperature (brightness?), but why can't I make a smaller image by having the source further from the lens than the image?

Conservation of etendue. If you make the image smaller, you have to lose some of its light - possible, but useless. Everything else would violate the second law of thermodynamics.

 

[nasu]

There is a lot of confusion and changing of direction in this thread (the most absurd of which is probably that you need a 4.04 GPA to get to Harvard) but the original question has an answer: the absolute best you can do is to have an image on the paper that is the same size and temperature as the filament of the light bulb. That is probably not enough to ignite a sheet of paper.

What do you mean by temperature of the image?

 

[Merlin3189]

Thanks. Darn thermodynamics, they spoil all our fun.
Thanks for the link. At least I know what I'm looking for now.
As for entendue, I thought that meant "understood". But I'm going to have to read about this a few more times before I understand it!

 

[mfb]

What do you mean by temperature of the image?

Once an object at the position of the image has the same temperature as the filament, it will be in thermal equilibrium of absorption and emission of radiation. Note that you need a full 4 pi solid angle coverage ("all around the target") with your optics to reach this.

 

[nasu]

So it is a shorthand for the maximum temperature an object can reach when the image is projected on it, right?

 

[houlahound]

Don't know the teacher but I would love to see his risk assessment for this type of instruction, sounds like a national headline any a court case waiting to happen.