Author Topic: What type laser has a beam you can see clear as day?  (Read 4689 times)
F96T12 DD VHO
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What type laser has a beam you can see clear as day? « on: August 16, 2018, 07:28:11 AM » Author: F96T12 DD VHO
Also where can I buy one for cheap but has good quality, I don't care what color it is, I just need a laser that doesn't take those stupid AG13 batteries.
Since pervious lasers that I've had that needed AG13 batteries die within two hours of usage and the whole assembly fails and it gets really annoying when the laser falls in two pieces because the screw strips. Also the beam never stays coherent for 20ft.
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dor123
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Re: What type laser has a beam you can see clear as day? « Reply #1 on: August 16, 2018, 07:38:36 AM » Author: dor123
You need a green laser of >100mW, which only available as DPSS laser. Pure diode green lasers, still not available in high wattage, and yellow lasers are very rare and are also DPSS lasers.
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I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.

I only working with the international date format (dd.mm.yyyy).

I lives in Israel, which is a 220-240V, 50hz country.

Max.
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Re: What type laser has a beam you can see clear as day? « Reply #2 on: August 16, 2018, 09:22:28 AM » Author: Max.
You also need to check out the legality of owning one, or you could end up out of pocket if it is seized by customs or postal authority. Plus you could find yourself being confronted by law enforcement.  :o
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Max.
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Re: What type laser has a beam you can see clear as day? « Reply #3 on: August 16, 2018, 01:27:46 PM » Author: Max.
You need a green laser of >100mW...

You must be already blind if you need a green laser rated above 100 mW just to see the beam spot in broad daylight. Besides, recommending such silly wattage for a pointer is plain stupid and downright dangerous - we're talking about the risk of permanent and severe eye damage here in case of accidental exposure!
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dor123
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Re: What type laser has a beam you can see clear as day? « Reply #4 on: August 16, 2018, 01:34:36 PM » Author: dor123
I've two green DPSS lasers of 30mW and 100mW. I tested them in my hostel, and seen that the 30mW isn't sufficient to see at full daylight.
I'm not blind at all.
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I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.

I only working with the international date format (dd.mm.yyyy).

I lives in Israel, which is a 220-240V, 50hz country.

Max.
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Re: What type laser has a beam you can see clear as day? « Reply #5 on: August 16, 2018, 01:51:32 PM » Author: Max.
...and seen that the 30mW isn't sufficient to see at full daylight.
I'm not blind at all.

You must be visually impaired, or the sun's particularly intense in Israel... I have a 7 mW green DPSS pointer (power measured with a actual lab instrument) and I see the spot outside in broad daylight without any problem (if it is not pointed too far away, that is). Sometimes I use it to prank local blackbirds, they often fall for the green luminous worm which they somehow cannot catch (I've seen birds acting crazy in frustration as a result lol).
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Mandolin Girl
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Re: What type laser has a beam you can see clear as day? « Reply #6 on: August 16, 2018, 07:36:21 PM » Author: Mandolin Girl
He is referring to the beam visibility, which to be fair is what the OP asked.
Seriously, what does "a beam you can see clear as day" even mean?

First of all, you don't see the beam in normal circumstances (i.e. clear weather), it's the spot, or the point where the beam meets an obstacle, that you actually see (meaning that actual visibility depends also on the nature of the obstacle and on the distance of observation). And second, what "see clear as day" means really? A small 1 mW HeNe laser beam projected onto a white wall in a normally-lit room, that's a perfect example of a laser spot that I can "see clear as day" under normal conditions. Really, that's a lousy question in the first place... so it is only reasonable to assume that the OP asked for a laser whose projected spot could be visible under daylight condition in the outdoors ("i.e. clear as day").
« Last Edit: August 16, 2018, 07:41:49 PM by Max. » Logged
Mandolin Girl
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Re: What type laser has a beam you can see clear as day? « Reply #7 on: August 16, 2018, 07:43:41 PM » Author: Mandolin Girl
Seriously, what does "a beam you can see clear as day" even mean?

First of all, you don't see the beam in normal circumstances (i.e. clear weather), it's the spot, or the point where the beam meets an obstacle, that you actually see (meaning that actual visibility depends also on the nature of the obstacle and on the distance of observation). And second, what "see clear as day" means really? A small 1 mW HeNe laser beam projected onto a white wall in a normally-lit room, that's a perfect example of a laser spot that I can "see clear as day" under normal conditions. Really, that's a lousy question in the first place... so it is only reasonable to assume that the OP asked for a laser whose projected spot could be visible under daylight condition in the outdoors ("i.e. clear as day").

Exactly, you will only see the beam when there are particulates in the air for the beam to refract off.
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F96T12 DD VHO
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Re: What type laser has a beam you can see clear as day? « Reply #8 on: August 16, 2018, 07:45:44 PM » Author: F96T12 DD VHO
Seriously, what does "a beam you can see clear as day" even mean?

First of all, you don't see the beam in normal circumstances (i.e. clear weather), it's the spot, or the point where the beam meets an obstacle, that you actually see. And second, what "see clear as day" means really? A small 1 mW HeNe laser beam projected onto a white wall in a normally-lit room, that's a perfect example of a laser spot that I can "see clear as day" under normal conditions. Really, that's a lousy question in the first place... so it is only reasonable to assume that the OP asked for a laser whose projected spot could be visible under daylight condition in the outdoors ("i.e. clear as day").
What I mean is: I want to see a beam without the use of smoke from a fog machine. I'm not going to be using the laser outside, I'll be using it in a room that has the blinds shut while the sun shines through the spaces. What do I mean by "clear as day" ?  it's right here https://i.pinimg.com/originals/a8/01/c9/a801c99c2cb234be0eb37dbf994c94bc.jpg
No smoke or anything, just a visible beam
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Max.
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Re: What type laser has a beam you can see clear as day? « Reply #9 on: August 16, 2018, 07:50:23 PM » Author: Max.
What I mean is: I want to see a beam without the use of smoke from a fog machine. I'm not going to be using the laser outside, I'll be using it in a room that has the blinds shut while the sun shines through the spaces. What do I mean by "clear as day" ?  it's right here https://i.pinimg.com/originals/a8/01/c9/a801c99c2cb234be0eb37dbf994c94bc.jpg
No smoke or anything, just a visible beam

As far as I am aware a beam like that is not possible outside the realms of special effects.  :-\

« Last Edit: August 16, 2018, 08:03:58 PM by Miss Cuddly » Logged
Mandolin Girl
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Re: What type laser has a beam you can see clear as day? « Reply #10 on: August 16, 2018, 07:57:54 PM » Author: Mandolin Girl
What do I mean by "clear as day" ?  it's right here https://i.pinimg.com/originals/a8/01/c9/a801c99c2cb234be0eb37dbf994c94bc.jpg
No smoke or anything, just a visible beam
OK, now the question makes sense, but it is still unclear how bright you want the beam to be on its own ("clear as day" is not a measure of anything).

If you want to see the laser beam clearly in a clean atmosphere (without smoke or dust flying around), then it actually has to be much, much brighter than the sun rays that shine through your blinds (you don't seen them clearly do you?). And that means massive power in the Watt range. At this level, you'll be blind from the laser spot projected onto your wall before you can actually see the beam clearly.

As for the picture you attached, it was taken in a slightly smoky atmosphere as there is no other way to make the beam from such a low-power device (certainly 5 mW or less) so clearly visible.  
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Max.
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Re: What type laser has a beam you can see clear as day? « Reply #11 on: August 16, 2018, 08:05:09 PM » Author: Max.
I have had a look at the website and from what I can see it is highly dangerous. If it performs as they claim I cannot see how they would get that sort of performance in that small a package.  :o

They claim that it has a 10 mile range, yet in the specs they say a project distance of 4,000m away, now my high school mathematics tells me that 10 miles is 16,000m.  ???
« Last Edit: August 16, 2018, 08:12:21 PM by Miss Cuddly » Logged
Max.
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Re: What type laser has a beam you can see clear as day? « Reply #12 on: August 16, 2018, 08:06:57 PM » Author: Max.
They can't, and that's why they usually use glycerin smoke (or simple cigarette smoke) in order to get the sort of pictures shown in the link - it sells better this way.
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Max.
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Re: What type laser has a beam you can see clear as day? « Reply #13 on: August 17, 2018, 07:37:54 AM » Author: Max.
Surmise. What do you think he means? For someone so obviously intelligent as you I am not sure why a basic turn of phrase is such a hurdle...
I thought the issue with the phrasing of the initial question would be obvious to you by now... so let's go back to "clear as day". What does it refer to exactly? does this mean:
- "a beam clearly visible in a completely dark room without any ambient light at all"?
- or is it a "clearly visible beam in a lit room"? If so, how brightly lit is the room?
- or, is that "a beam clearly visible in open daylight in the outdoors"? and if so, is that at noon, at dusk, etc?
- ...
well, you get the idea (I hope so, because I cannot spell it out more precisely to you). "clear as day" is confusing at best, and as I said earlier, without any precise context this does not provide any useful information about the desired beam brightness.

The sun's rays aren't collimated into a tiny coherent beam of light. You don't need a laser in the range of Watts to see its beam at all - in a room with the blinds closed a 50-100mW device will suffice
The radiation's coherence or beam size has nothing to do with what you're point out. The sun-earth distance is sufficiently large compared to the blinds-floor distance in a room (this is typically a billion-to-one ratio) to consider the sun rays filtered through the blinds to be effectively collimated rays of light. The point I made earlier is that the path of those rays through the atmosphere of the room, with the typical solar irradiance at the earth's surface (around 400 W/m² after filtering through the atmosphere, if I remember correctly), is barely visible at all under normal conditions, therefore you need a laser beam with a much, much higher optical power density if you want to see it clearly under the same circumstances (i.e. room with the same ambient light level). If we take a laser beam three orders of magnitude brighter than the typical sunray, then that brings us indeed in the Watt range - and this is needed in a room which is not in complete darkness (closed blinds don't block out outdoors' light nearly as effectively as a black canvas.

Now, as for your example of the 50-100 mW laser pointers whose beam you can see very clearly at night while pointing at stars: you have to take into account for the Mie scattering of light by the atmosphere, which makes the beam most visible at shallow angles only (the angular distribution of optical scattering is not isotropic and is strongest along the beam's axis). That's why the same beam is not nearly as visible when you look at it at right angle, which I would expect is the case in the present situation referred to by the OP (unless he is crazy enough to consider looking in the beam's direction and/or close to it without protection). And that's why you can also perfectly see the beam from a weak 5 mW HeNe laser at night in the outdoors if you place yourself close enough from the beam in the right direction (i.e. towards or away from the laser)...
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wattMaster
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Re: What type laser has a beam you can see clear as day? « Reply #14 on: August 17, 2018, 07:56:20 AM » Author: wattMaster
I thought the issue with the phrasing of the initial question would be obvious to you by now... so let's go back to "clear as day". What does it refer to exactly? does this mean:
- "a beam clearly visible in a completely dark room without any ambient light at all"?
- or is it a "clearly visible beam in a lit room"? If so, how brightly lit is the room?
- or, is that "a beam clearly visible in open daylight in the outdoors"? and if so, is that at noon, at dusk, etc?
- ...
well, you get the idea (I hope so, because I cannot spell it out more precisely to you). "clear as day" is confusing at best, and as I said earlier, without any precise context this does not provide any useful information about the desired beam brightness.
Hold on, so why not check every one of those cases? That way the OP doesn't have to specify any particular one.
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