Safety? What safety?

Posted by HELiX

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Comments(0) 3:22 AM 11 November 2007

Science Team Camp 2007

Posted by HELiX

This came late, but oh well.

14th to 16th November was BP Science Team Camp. I won’t blog much about it, though. I don’t feel like giving another long entry.

But basically, ST camp was pretty much heading for disaster after the teachers decided, against the sec 3 organisers’ will, to have it as a rather lame 3D1N camp. Yes, you read that right. And also, blend in BP’s Inter Primary School Science Quiz into it.

Now that makes it doubly lame.

So I tried to go back to ask for 3D2N back, nada. In the end, after removing that one night plus an entire morning, ST camp was looking the removal of every event with the word ‘games’ in it - War game, wet games and dry games. A camp without games… awesome.

Ultimately, treasure hunt was replaced with war game. But it’ll still go ahead without wet and dry games. And treasure hunt, of course.

Anyway, pictures can be found here!

A proper entry can be found on DW’s blog.

Comments(0) 2:34 AM 11 November 2007

Lab@Home: High-Power Mini Maglite Laser

Posted by HELiX

This goes as attempt number 3, and a successful one. Cheers! :D

CLICK HERE to link to a nicer looking page.

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1. Introduction
2. Overview
3. Materials
4. Construction
   3a. Laser Diode
   3b. Optics
   3c. Laser Housing
5. Results

The objective of this project is to create a high-powered laser pointer, with sufficient output to fall under the class IIIb category of laser classification.

A normal red laser pointer used in presentations are class IIIa, having an output of <1 mW.

The decently high-powered green lasers pointers used in astronomy for pointing out stars and constellations, are at the legal limits of a class IIIa laser pointer, rated at <5 mW, and they are easily 50 times more powerful than the standard red lasers used in presentation. The colour green, at 532nm wavelength is also the most sensitive colour to the human eye, thus their laser beams can be seen clearly into the nightsky.

More info:

“Class 3a lasers are capable of emitting visible and/or invisible laser radiation with the maximum accessible emission levels as specified. As for visible Class 3a laser dvices, they operate in a power range of 1 -5 mW, which have irradiance in the emergent beam of not more than 25 W/m2. This class of laser are not capable of damaging the eye because of the person’s normal aversion response to bright light, unless the radiation is stared at for a long time, or unless binoculars or optical instruments are used. Many construction alignment lasers fall into the class 3a category.

Class 3b lasers are medium-power and moderate-risk laser devices that are capable of emitting ultraviolet, visible or infrared laser radiation with specified maximum accessible emission levels. It can be in continuous wave or pulsed mode and operating in a power of 500 mW or less for emission duration of longer than 0.25 sec, or a radiant exposure of 100 kJ/m2 or less for emission duration shorter than 0.25 sec. These lasers are capable of causing accidental injuries by exposure from the direct or specularly reflected beam. Diffuse laser beam reflections from class 3b are not hazardous, but may be so if focused to eyes with optical instruments. Therapeutic, acupuncture, bio-stimulation lasers, military laser range finders and designator are all under class 3b lasers.”

Class IIIb are thus not legally permitted for use by individuals in Singapore.

Funnily enough, CD/DVD drives are classified under both Class I and IIIb. Class I makes the product legal for consumer to own because it complys with “no individual, regardless of exposure conditions to the eyes or skin, would be expected to be injured” by the product. Class IIIb refers to the particular laser diode within the CD/DVD drive itself, which is highly dangerous.

Using the laser diode from a CD/DVD drive, I plan to create a homemade Class IIIb laser, which has sufficient output power to melt thin plastic and tape, possibly light matches and pop balloons. Also, another main purpose is a workaround to the Singapore Law, which does not permit the importing of Class IIIb lasers. The laser would have a power rating of over 200mW.

1. DVD Burner laser diode
2. Mini Maglite (AA batteries)
3. Focusing Lens Module (AixiZ Laser Module)
4. Tools

First of all, another set of warnings/disclaimers before you get excited over this project:

1. Class IIIb lasers are dangerous; exactly why they’re restricted by law in the first place. Obviously, do not point the laser into anyone’s eyes at all costs. The beam is even dangerous if you look at it on a reflective surface (glass, metals, and even white surfaces), so eye protection is highly recommended!
2. If you become blind it’s not my fault. I told you to use protective goggles, and stay AWAY from reflective surfaces!!! Really.

Laser Diode

This project is a continuation from High-Power Laser Attempt 1 and High-Power Laser Attempt 2, from which titles you can guess, are failures at attempting this project. In both attempts, I have tried to extract the laser diode from DVD Burner and CD Burner drives. One occasion I overvolted my laser diode, and the other, fed too many current. Both diodes died.

Although I learned my mistakes, I couldn’t swallow spending quite a bit on this project and ending up with failures. I got sick of buying DVD Drives to tear apart just for a tiny diode. I had this project on hiatus, pending abortion, until I saw an online mass order for DVD Burner laser diodes. I joined in the mass order and I received the diodes 3 weeks later.

That’s the little fella.

If you wish to extract the laser diode from a DVD Burner instead, you can just follow my previous attempts at here and here. However, of course, do NOT test the diode like what I did. Doing so will only dry your diode. Instead, assume all is well and that your diode is working fine. All that remains is to extract the diode from the metal heatsink that it is very tightly attached to. There are various ways to remove the diode from the heatsink, and has to be done VERY carefully if not you’ll end up destroying the fragile diode. For example, you could use a dremel rotary tool on the heatsink, until the metal cracks apart. The diode is soldered in, so an alternative is to use a solderwick to extract the solder, and clean off any remaining solder with a needle file. Or use whichever method that suits you best, as long as the diode falls out without you hurting it.

If you read my previous attempts at extracting the laser diodes from DVD Burners (until I fried them), a successful extraction will produce something similar to these, although in a more poorer condition.

Optics

Laser diodes don’t emit a collimated beam, instead they emit an ellipsed-shape beam that’s unfocused.

So to focus the laser beam into a nice sharp beam, we’ll need the lens and optics. I bought a lens module from AixiZ and had it mailed to me.

[Insert funny comment on ignoring the DANGER sticker]

I peeled off the sticker without a second thought and unscrewed the lens module. It was quite tightly screwed, so I had to do this:

The rubber band protects the nice new lens module casing from being scratched and all, while providing good friction.

From here, I took the module apart entirely.

It is typically made of these components.

However, the lens module comes with a laser diode preinstalled. It wasn’t easy to remove at all. As much as I wanted to save the diode for future use, removing it involved hitting it out with a stick and a hammer directed right into the front end of the diode. ‘Nuff said.

Before installing the new diode into the lens housing, I applied small amounts of Arctic Silver 5 thermal paste at where the diode will go into.

Installing the diode in the lens housing wasn’t easy, too. Using the brass end of the lens module, there’s a small hole at its end. I placed this over the diode, with the lens fitting through the hole, and hammered the diode in until it was flush.

Finally, attach back everything excluding the brass end.

Laser Housing

Of course, I needed a cozy housing to keep my lens module with the laser diode powered by batteries and a switch.

While it is possible to make your own circuit, there is a simpler method to doing this. The reason why it isn’t as simple as attaching batteries is because, as I have done in my previous attempts, the current drawn from the battery is too great and it will fry your laser diode. As diodes get hotter, resistance decreases, letting more current pass through the diode, which causes more heat, and so on in a snowballing effect. Finally the diode hits a critical temperature and it blows.

The current supplied by the battery is rather stable, but in most cases, is too much to drive a laser diode. For instance, a DVD-burner laser diode would need about 200-250mA of power at about 2.5-3 volts (for any long life span to actually be expected of the diode). Laser diodes are, unfortunately, a very light load when wired directly to a battery, and an alkaline battery would easily put out about 500mA or more, and lithiums put out 2 or 3 times that much! This too is an instant death situation for our beloved laser diode.

For this project, we have decided to choose the simplistic path and use a flashlight with the right current regulation.

A Mini Maglite was chosen because it provided the current regulation needed in its internal circuit. The current supplied is around the 200-250mA required by the laser diode.

First, take everything apart, as always.

The metal reflector will hold the lens module in place, so I drilled to expand the hole.

The design of the Mini Maglite is also very suitable for this project. The connection to the diode is done using two long leads, as seen here with the original bulb.

I used some White Tack to stick the lens module on.

And fit everything back nicely…

Of course, the original plastic cover doesn’t go back on because not only it doesn’t fit, but the laser also loses power as it goes through it, and we don’t really want that.

From here, it is important to note that focusing is VERY important. Focusing is done simply by turning and adjusting the lens of the lens module. Aim the laser at a black surface, and observe the size of the laser dot each time you stop, adjust and try again. Every slight bit matters. The laser dot may look focused and small, but we’re looking for the SMALLEST. Even fraction of a millimetre counts.

And now, the results…!

To show how much focusing matters, I started off with a rather focused laser beam. Yet, it was unable to even light matches after a long period of time!

After precise focusing, the following results can be achieved.

Balloons were also good targets. Have a look.

However, the same focusing doesn’t work for all distances. A laser beam focused to light matches at close range will produce a horrible fat red smudge when pointed to a further wall. It must be refocused to use for long ranges.

After refocusing, pointing into the night sky…

I read somewhere online that someone measured this Mini Maglite Laser, and reported that it was rated at 250mW. The person also used a high-end laser checking device, and 250mW looked reasonable, although a bit on the high side for a DVD Burner laser diode.

But still, I wanted to be certain. It happened that the lab I’m attached to at NUS had a Coherent LaserCheck lying around.

Now this device isn’t as accurate and high-end as the LPM-1 measurement device used by the person online, but it was all I got. Also, it looked really simple and cheap. And so I tested my laser on it!

Values were ranging between 130-200 mW, depending on how well I focused the laser beam, and angle of incidence into the sensor. After numerous tries, it registered a peak reading of 204mW!

While it’s still short of the 250mW reported online, I’m glad it broke pass 200mW.

Results are great!

Comments(0) 5:52 PM 11 November 2007

Comet Holmes Larger than the Sun?!

Posted by HELiX

Sorry to throw in astro here but I’m trying to get into the mood for IOAA. But I found this quite interesting, so you should, too.

…

A comet that has delighted backyard astronomers in recent weeks after an unexpected eruption has now grown larger than the sun.

The sun remains by far the most massive object in the solar system, with an extended influence of particles that reaches all the planets. But the comparatively tiny Comet Holmes has released so much gas and dust that its extended atmosphere, or coma, is larger than the diameter of the sun. The comparison is clear in a new image:

Comet Holmes (left) from the 3.6-meter Canada-France-Hawaii telescope on Mauna Kea showing the coma at 869,900 miles (1.4 million kilometers) in diameter. The white ‘’star” near the center of the coma is in fact the dust-shrouded nucleus of the comet.The sun and the planet Saturn are shown at the same scale for comparison. 

“It continues to expand and is now the largest single object in the solar system,” according to astronomers at the University of Hawaii.

The coma’s diameter on Nov. 9 was 869,900 miles (1.4 million kilometers), based on measurements by Rachel Stevenson, Jan Kleyna and Pedro Lacerda of the University of Hawaii Institute for Astronomy. They used observations from the Canada-France-Hawaii Telescope. The sun’s diameter, stated differently by various sources and usually rounded to the nearest 100, is about 864,900 miles (1.392 million kilometers).

Separately, a new Hubble Space Telescope photo of the comet reveals an intriguing bow-tie structure around its nucleus.

The comet’s coma-mostly microscopic particles-shines by reflecting sunlight.

See for yourself

Holmes is still visible to the naked eye as a fuzzy star anytime after dark, high in the northeast sky. You can find it by using this sky map. It is faintly visible from cities, and from dark country locations is truly remarkable.

“Right now, in a dark sky it appears as a very noticeable circular cloud,” said Joe Rao, SPACE.com’s Skywatching Columnist. Rao advises looking for the comet this weekend, before the moon becomes more of a factor. The comet will likely diminish in brightness yet remain visible for the next two to three weeks, he said.

“Over the next few weeks and months, the coma and tail are expected to expand even more while the comet will fade as the dust disperses,” Stevenson and her colleagues write.

On Monday, Nov. 19, the comet will create a unique skywatching event with its see-through coma, according to the Web site Spaceweather.com: “The comet will glide by the star Mirfak [also called Alpha Persei] and appear to swallow it-a sight not to be missed.”

A small telescope will reveal the fuzzy coma. Lacking a long tail characteristic of some great comets, however, Holmes is not the most dramatic object in the sky for casual observers.

Mystery outburst

Nobody knows why Holmes erupted, but it underwent a similar explosive brightening in 1892. The recent display, which began Oct. 24, brought the comet from visual obscurity to being one of the brighter objects in the night sky. It has since dimmed somewhat as the material races outward from the nucleus at roughly 1,100 mph (0.5 km/sec).

The Hawaiian astronomy team writes in a press statement: “This amazing eruption of the comet is produced by dust ejected from a tiny solid nucleus made of ice and rock, only 3.6 kilometers (roughly 2.2 miles) in diameter.”

The new image from the Hawaiian observatory also shows a modest tail forming to one side, now just a fuzzy region to the lower-right. That’s caused by the pressure of sunlight pushing on the gas and dust of the coma.

But the comet is so far away-149 million miles (240 million kilometers), or about 1.6 times the distance from Earth to the sun-that even Hubble can’t resolve its nucleus.

The offset nature of the coma, seen in ground-based images, suggests “a large fragment broke off and subsequently disintegrated into tiny dust particles after moving away from the main nucleus,” Hubble astronomers said in a statement today. The comet’s distance, plus all the dust, prevent Hubble from seeing any fragments, however.

Comments(0) 4:51 PM 11 November 2007

RSS/Atom Feeds Fixed

Posted by HELiX

Finally fixed my RSS/Atom feeds after a long while. Sorry to my subscribers, including myself.

…Yes I subscribe to my own feed d’you have a problem with that?

Well, here it is: http://feeds.feedburner.com/helix

Apparently one particular plugin was causing the problem. Deactivated it and all is well now.

Comments(0) 5:35 PM 11 November 2007

Portal’s Still Alive

Posted by HELiX

Wei Rong posted this ages ago but finally I can host the illegal song here.

Really, it’s really legal. I don’t think they copyrighted that song for the game.

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…

…

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Ellen McLain (GLaDOS) - Still Alive

This was a triumph.
I’m making a note here: huge success.
It’s hard to overstate my satisfaction.

Aperture science.
We do what we must because we can.
For the good of all of us
Except the ones who are dead.

(Chorus 1)
But there’s no use crying over every mistake
You just keep on trying till you run out of cake
And the science gets done and you make a neat gun
For the people who are still alive.
I’m not even angry.
I’m being so sincere right now.
Even though you broke my heart and killed me.
And tore me to pieces.
And threw every piece into a fire.
And as they burned it hurt because
I was so happy for you.

(Chorus 2)
Now these points of data make a beautiful line
And we’re out of beta we’re releasing on time.
So I know I got burned think of all the things we learned
For the people who are still alive

Go ahead and leave me.
I think I prefer to stay inside.
Maybe you’ll find someone else to help you.
Maybe Black Mesa -
That was a joke. Haha. Fat chance.
Anyway, this cake is great:
It’s so delicious and moist.

(Chorus 3)
Look at me still talking when there’s science to do.
When I look out there it makes me glad I’m not you.
I’ve experiments to run there is research to be done
On the people who are still alive

And believe me I am still alive.
I’m doing science and I’m still alive.
I feel fantastic and I’m still alive.
While you’re dying I’ll be still alive.
And when you’re dead I will be still alive.

Still alive
Still alive

Comments(0) 1:37 AM 11 November 2007

New Web Host

Posted by HELiX

After nearly a year with my old Singapore web host, I have decided to move on with a Malaysian one.

The propagation from my old host to the new host took place today, was rather smooth actually. And it was really easy and automatic, I should add.

Apparently, my new host offers 4 months of FREE hosting if I were to transfer my website to them while it is still under contract. My contract is left with less than 2 weeks, what better time is it to move now and gain the 4 months bonus :D

Now, I have 10GB of storage, but I won’t say how much bandwidth in case you people have the smart idea of attempting to crash my server (yes, I’m looking at you, Shaun Ng). I don’t think I blogged about this before but there was this IP address, a Singapore one, which kept crawling my server. Not sure if it’s a bot or what, but it took down a massive 20GB+ of bandwidth after a week or two. Inhuman, you might call it.

That’s 4 times my allocated bandwidth of my previous host. Ah well I banned that IP anyway.

This is where I sincerely thank and praise my previous Singapore web host. Really good service, replies to emails within 10 minutes, and… best of all? DOESN’T SUSPEND YOUR ACCOUNT WENT YOU OVERSHOOT YOUR LIMITS. Yup, they kindly smsed me when I overshot the bandwidth by 4 times, and also kindly reminded me that I was using over my 200MB storage limit. Never once was I suspended even though I ignored their reminders.

Really good stuff I had for the past 1 year.

But 200MB wasn’t good enough for me, so I decided to move on to the current web host. As of right now I’m paying nothing. But coming in March, I’ll be asked to pay up my bill. It’s more expensive than the Singapore one, but hey, 10GB?

The new Malaysian web host has a rather good service as well. Prompt replies and all I had to for them to transfer my domain to their server was tell them my CPanel username and password, and contact my old web host to change the domain’s DNS.

After 5-6 hours, the propagation is completed and I’m happy with my 10GB.

I’ll reveal the power of 10GB in the coming weeks. Stay tuned :)

Comments(0) 1:12 AM 11 November 2007