About this project
Video (version 2) has been uploaded. It's much shorter and to-the-point. Thanks to everyone who gave me constructive feedback!
Green and violet laser pointers have become inexpensive, portable, and widely-available in recent years. Due to the unique properties of green and violet light, these lasers can induce fluorescence and phosphorescence in common household materials and geologic minerals! If you think the images below are cool-looking, remember that photos simply cannot capture the beauty and intensity of these effects.
Image 1: extra virgin olive oil fluorescing orange when illuminated by 532-nanometer (green) laser light.
There are several other cool effects that you can produce with these pointers, such as total internal reflection and phosphorescence, both of which are in the title image. You can show off this eye candy at parties or in classrooms to get everyone's attention!
How Kickstarter plays into this
There are two reasons I’m launching my project through Kickstarter:
First, I’ve been spending my own money to conduct independent research. To continue my search for cool specimens, I want to raise funds so I can buy lasers of different colors and purchase new test samples. Science isn't cheap!
Second, I want to distribute my findings so that science teachers, museum exhibitors, lecture demonstrators, and science fairgoers can use these principles with minimal delay. If people (educators or otherwise) want to acquire a kit, pledging a certain amount saves them the trouble of going out and hunting for the materials themselves.
Image 2: manganese-rich calcite flaring a brilliant orange-red when exposed to a 405-nanometer (violet) laser due to both fluorescence and scattering. The Sharpie is used for scale and as a target for my poor camera to focus on.
What's all this stuff about education?
Lasers are amazing by their own merit, so it doesn't matter if you're a teacher, investment banker, singer/songwriter, or an underwater basket-weaver! However, I teach 60+ students every semester, so I see these lasers as an educational tool. Every science teacher will agree that something dazzling must be occasionally rolled out to refocus and re-engage a class full of sleepy students. Lasers fit the bill nicely, because:
- A shifting rainbow of colors has nearly universal appeal. Students don't need to be sci-fi fans to enjoy a laser light show!
- Unlike many science demonstrations that create excitement (e.g. demos involving explosions and fire), lasers and their targets only need to be bought once.
- The concepts covered by the lasers are multidisciplinary in nature, with applications in biology, optics, spectroscopy, mineralogy, electromagnetism, and chemistry.
Image 3: extra virgin olive oil glowing red when struck by a 405-nanometer laser. For this to work, the oil must be extra-virgin, presumably because EV oils are obtained by physical crushing, while many other varieties are extracted with chemical solvents. The resulting oil will still fluoresce, but the activators that produce this red glow are gone.
What do you, the reader, get out of pledging?
Besides promoting independent research, pledging brings you a tangible reward. When's the last time your taxpayer dollars did that?
Pledging just a dollar demonstrates your interest and puts you in the loop! Not only will I send you a document detailing everything I’ve discovered so far, I’ll keep you updated about my progress so you'll hear about new developments first!
If you are interested in obtaining the lasers or a complete kit, please pledge more! I know that's asking for a lot, given our difficult economic climate. Schools, universities, museums, community outreach organizations, and other institutions may benefit from a kit shared among educators, rather than individual ownership.
Image 4: corundum (the mineral that makes up rubies and sapphires) glowing a deep red when exposed to 405-nanometer light. The effect is drowned out by the intense blue fluorescence of the white napkin that was also struck by part of the laser beam.
Thanks for reading, and please support my efforts!
Please spread the word, especially if you know a science teacher/professor/demonstrator. Send this page to your friends, your family, or fellow educators! I'll be ready to answer any questions you may have, so send queries through Kickstarter or to ahuang (at) ua (dot) edu.
Image 5: a series of four samples fluorescing under 405-nanometer light: (from left-to-right) laundry detergent, orange highlighter extract, pink highlighter extract, and tonic water.
FAQ
-
Q: Isn't it dangerous to bring lasers into a classroom?
A: That depends on the caliber of the teacher and the maturity of the student. The teacher's job is to impress the hazards of laser use onto the student and set a good example. The maturity of the student is not a function of age, but is strongly correlated. A good rule of thumb is that if a student has demonstrated the ability to safely handle 6M hydrochloric acid, he or she is mature enough to handle laser pointers.*********************************************
Q: What is a "safe" output level for a handheld pointer?
A: In the United States it is generally accepted that a power output of 5 milliwatts (mW) or less is low enough for general use. In Australia, this limit is 1mW. In theory, at these levels the blink reflex will activate before permanent eye damage can occur. 5mW is the standard I go by; it is strong enough to produce beautiful scientific demonstrations, but not enough that accidental exposure or diffuse reflection will cause eye damage.*********************************************
Q: My violet (405nm) laser seems dim. Should I get a higher-output laser?
A: No! Our eyes are much more sensitive to green light than red or violet light. That is why a 5mW green laser (532nm) will appear far brighter than a violet or red (650nm) pointer. If you take a photograph of a red or violet laser dot, it will appear very bright because the camera is more sensitive to the ends of the visible light spectrum than our eyes are.*********************************************
Q: Does a violet laser have the same hazards as UV light?
A: Fortunately, no. The 405nm laser carries an energy of about 3 electron volts per photon, which is not enough to ionize what it hits (i.e. not energetic enough to strip electrons from their atoms or tear apart chemical bonds). As you move past violet into the ultraviolet spectrum, each photon carries higher and higher energy, which can cause eye and skin damage.*********************************************
Q: So...it's probably a bad idea to use UV lasers for demonstrations?
A: Most likely. An invisible laser that can cause colorful fluorescence in different materials would be the coolest science demonstration ever, but the safety concerns and lawsuits aren't worth it. UV lasers are easily obtainable, but I don't play with them because even diffuse reflection (i.e. the laser dot hitting a non-reflective surface) might cause eye damage. Even if you take appropriate safety precautions like issuing UV-proof googles and sunscreen, there's still the legal issue of exposing students to potentially hazardous radiation. Science becomes a lot less interesting when you throw overprotective parents in the mix :-(*********************************************
Q: What components (or lack thereof) can be hazardous?
A: As mentioned in a previous FAQ, certain laser pointer components are necessary for safety reasons:
- The first is the driver, which regulates electric power to the laser - obviously a damaged or missing driver will result in harm to the user or other laser components.
- The second is the heatsink, which is only necessary in certain laser pointers. It collects and dissipates excess heat, again preventing damage to other components.
- Finally, an infrared (IR) filter blocks excess IR radiation from leaving the laser pointer's aperture. A missing IR filter means a laser rated at 5mW is not only outputting 5mW of visible light, but emitting 30mW or more of invisible IR radiation as well! This is only a problem in certain laser pointers (see the "What is DPSS" FAQ), and only dangerous when directed at someone's eyes.*********************************************
Q: Is there anything else I should worry about?
A: Watch out for retroreflectors - these objects backscatter 90% or more of incoming light regardless of which direction the light came from. Examples are stop signs, reflective strips on orange safety vests, and the reflectors mounted on bicycle frames and pedals. Also, directing a laser beam at eyes or vehicles can range from a misdemeanor or felony depending on location and malicious intent. -
Yes! The only exception is Australia; since 2008, laser pointers with an output higher than 1mW are prohibited in that country. See for this page for more information.
-
DPSS stands for "Diode-pumped solid-state," and are derived from diode lasers (red and violet pointers contain diode lasers). DPSS lasers are typically more compact and more efficient than older types of lasers, but less so than diode lasers. The name comes from a two-step process: a diode "pumps" a crystal (the "solid state"), which then emits laser light of a certain wavelength.
The 532nm green laser is a DPSS laser with an additional step. The infrared light produced by the DPSS portion passes through a crystal that halves its wavelength to 532nm. This process is moderately inefficient and a large portion of IR light invariably escapes, necessitating the use of an IR filter (see safety questions above).
-
Yes! 405nm pointers have the same laser diodes as Blu-Ray DVD players and Playstation 3s. Blu-Ray lasers are technically purple!
-
No, I haven't. I have very little formal training in science education, and my other commitments as a graduate student prevent me from obtaining it, at least for now. I encourage teachers and researchers to explore this avenue, though.
-
With some sellers like Arbor Scientific or ThinkGeek you'll find green and violet laser pointers for $70 while in other places like Ebay or Amazon you'll find them for $5. This disparity arises from differences in construction quality, quality control, and other miscellaneous reasons.
- Construction quality: The cheaper laser pointers are *probably not* knockoffs (e.g. a green light-emitting diode being sold as a laser), but their construction *probably is* lower-quality. You never want to buy cheap equipment for scientific experiments or for teaching laboratory courses, but a cheaper one will suffice for hobbyists and demonstrators. Lower-quality laser pointers may fall apart or wear out faster, their electrical components may be poorly assembled, and in the case of DPSS lasers, the heatsink and infrared filter may be poorly constructed or simply omitted (see "What is 'DPSS'" below).
- Quality control: More expensive lasers are extensively tested before they leave the factory/warehouse to make sure that they have reasonably consistent output (laser doesn't randomly get brighter/dimmer), that the output falls within legal guidelines, and that the beam is properly focused. All of this takes time, energy, and good equipment, so that's another reason for the large price gap.
- Miscellaneous reasons: lasers manufactured in China are cheaper due to lower labor costs. Also, pricier lasers usually look nicer, having streamlined casings and shiny clips. These fancy finishes drive up machining and material costs.
The lasers sent to pledgers will be on the cheaper end to cut down costs - but not so cheap that they will fail within an hour of use. I've been using the same $15 lasers for over a year now, and they've gone through several sets of batteries apiece.
Have a question? If the info above doesn't help, you can ask the project creator directly.
26
Backers
$1,123
pledged of $2,500 goal
0
seconds to go
Funding Unsuccessful
This project reached the deadline without achieving its funding goal on January 20.
Pledge $1 or more Pledge $1 or more
Pledging a dollar puts you in the loop! You will receive an electronic copy of what I've discovered so far. Plus, I'll update you about new developments via email!
Pledge $10 or more Pledge $10 or more
In addition to the above, you will receive a laboratory exercise in which students explore optics and spectroscopy with laser pointers and various non-hazardous materials. The exercise was designed by me and intended for students 12 and older.
Pledge $25 or more Pledge $25 or more
Rewards #1 and #2, plus your choice of a green or violet laser pointer! Also comes with a PDF about lasers and eye safety, designed by me.
Pledge $35 or more Pledge $35 or more
Rewards #1 and #2, plus one green AND one violet laser pointer! Also includes the PDF about lasers and eye safety.
Pledge $50 or more Pledge $50 or more
You get everything from above, plus a starter set of five non-hazardous liquids in glass vials. These are the samples you see throughout the page.
Pledge $60 or more Pledge $60 or more
On top of everything above, you receive two test tubes for demonstrating total internal reflection. One is full of tonic water for the violet pointer, and the other is full of dilute Pine-sol for the green laser.
Pledge $75 or more Pledge $75 or more
In addition to the previous rewards, you get two small mineral samples that glow beautifully under violet laser light. They are similar to the examples shown in the pictures.
Pledge $95 or more Pledge $95 or more
To cap off all the rewards listed above, you also receive a small piece of phosphorescent calcite from the Sterling Hill Mine in New Jersey (central title image). Sterling Hill ore is world-renowned for their fluorescent minerals.
Project By
Has not connected their Facebook account.
I am a graduate student pursuing a master's degree in hydrogeology. In my free time, I enjoy reading, investing, lifting heavy objects, teaching science to little kids, and glaring sternly at cameras.
