Intro: Laser Ball
Truth be told it's actually a Rechargeable Remote Control and Programmable Laser Ball... whoa!
So what's a Laser Ball?
Well it's sort of like the Death Star... OK, maybe that's a bit over-dramatic... a Laser Ball is like a programmable disco ball... or a cat-toy for humans (that sounds about right)... or a personal laser light show... the most fun you've had throwing a tennis ball in years(yeah!)... a 21st-century ship in a bottle... the most sophisticated poi or juggling ball ever seen... maybe a first-generation lightsaber training droid?... or maybe it's all of them! Check out the video to see how it works and how to make one then tell me what you think.
I thought this project was a good idea for an Instructable for a number of reasons:
- It's fun to build!
- The building blocks are easily accessible (...open-source much?) and there's a 5-min version that is lot's of fun too
- The project builds upon the open-source and DIY community
- Laser balls can be assembled in an afternoon
- There are a lot of potential variations (batteries, laser color, laser count, etc...)
- If you think lasers are cool (or any blinky light for that matter) than a Laser Ball will blow your socks off!
Step 1: Project Overview
Before getting starting on building a Laser Ball, let me begin with a brief explanation on the format of this Instructable. The first step here will list out scope of the project. The next step shares a little background on Lasers and their unique qualities (sort of an editorial piece). Then the main Instructable begins... Steps 3-8 describe each component in the Laser Ball with some useful information and complimentary links. Step 9 describes the assembly process which was shown in the video. Step 10 is a sort of "mini-instructable" on how to build a "5-min Laser Ball". Some useful details for taking laser pictures are in Step 11, and the process I went through to build this Instructable is described in Step 12. If you just want the details on how to build the laser ball jump to the Assembly step.
To start here's a breakdown of the specifications, steps, timeline, parts, cost, suppliers, tools, and wiring diagram for a full Rechargeable Remote Control and Programmable Laser Ball.
Laser Ball Specifications:
- Total optical power: ~70mW
- Current draw (max): ~300mA
- Operating voltage: 3.3V
- Battery life: ~2.5hrs (but its rechargeable!)
- 1.00 hr - Preparing and gathering materials/tools
- 0.25 hr - Thinking through the design
- 0.50 hr - Preparing the Teensy
- 0.75 hr - Cutting and installing diffraction gratings
- 0.50 hr - Drilling the tennis ball
- 0.50 hr - Installing lasers
- 1.00 hr - Soldering lasers, Teensy, and JST connector
- 0.50 hr - Squeezing components into tennis ball
- 5.00 hrs
- $42 - Red lasers (14) (Buy from Aixiz)
- (Buy from DealExtreme) Note: These DealExtreme lasers are slightly different than the Aixiz lasers. The DX lasers are smaller and cheaper but the cap is glued in place which makes adding the diffration grating much more difficult.
- $9 - Battery (Buy Li-Ion batteries from Sparkfun)
- $16 - Teensy microcontroller (Buy from PRJC)
- $5 - IR remote (Buy from Adafruit)
- $2 - IR receiver (Buy from Adafruit)
- $2 - Diffraction Grating (Buy from Edmund Scientific) (Buy from Ebay)
- $1 - JST connector (Buy from Sparkfun)
- $1 - Tennis Ball (your closet...)
- Soldering iron
- Wire strippers/cutters
- Hobby knife
- Masking tape
- Helping-hands/alligator clips
Update: As part of this overview I've also included two additional images showing the wiring diagram and schematic.
Step 2: From Light Bulbs to Lasers...
Skip this section if you don't want to hear my dramatic soliloquy about lasers and lightbulbs
Lasers have captivated people's imaginations for years, in fact, 2010 marked the 50th anniversary of invention of the laser (way to go laser!). Since then, lasers have blossomed into a industry of both entertainment and science, and generated countless new innovations across the world. I'd only crossed paths with the occasion laser pointer before I started my engineering career (...and of course I unkowningly used them in things like DVD players, but that doesn't really count...). However, it wasn't long before I was able to understand why lasers represented something much more than just a replacement to a pointing-stick.
For me, it wasn't until I grasped the concept of etendue and semiconductor manufacturing that I could really appreciate, not only the potential of the laser, but why it will remain an everlasting tool for generations to come. So first let me briefly the concept of etendue.
Etendue is a funny little french word which translates to something like "extended" or "expansive." However it describes a very fundamental idea; something along the lines of how light spreads out from its source and illuminates over a volume, (...that's the wikipedia definition, anyway) but the the idea of etendue is much simpler to understand.
Let's imagine back around 1880, Edison tucked away in his lab testing filaments for his light bulb, each filament he tested glows hotly as electricity completes its circuit. The soft warm light being generated from his small filament is at the time a very profound way to generate light but if you think about it... it's quite crude... (warning: exaggeration ahead) it's equivalent to popping a balloon to create a breeze or using a stick of dynamite to dig a hole.. sure that's one way to do it but it makes a mess, light goes everywhere, you're covered in light and there's no way to clean it up! (...etendue is basically the optical equivalent to the second law of thermodynamics... you can't create more energy than you put into the system, so even if you add mirrors and lens the etendue can never be decreased... its invariant!)
So let's change the scenario, now we've got a laser and we can picture it buzzing out a little hole and shooting across space as a pencil thin beam of light. It's certainly very clean looking, but what did we change? Well we did a couple things, in simple terms: 1) we made all the light a single wavelength/color and 2) decreased the etendue of the light by many, many orders of magnitude,(...we're talking lots of zeroes here folks), the light has high optical power, emitted from a small source, and well defined in angle. We have rays of light playing together in harmony, synchronized and smooth, rather than a dissonant collection of rays blasting out notes of dissonant frequencies in all directions.
With a laser we've basically captured the genie the in bottle; a way to make light in a pure form, a perfectly smooth undulating wave of light whose collection of rays travel in one direction in perfect synchronization. This means a laser is more or less light distilled into its basic element and packaged to make it easily controlled and distributed; it's Henry Ford's assembly line mixed with the 1's and 0's in a microprocessor... so this is where the semiconductor manufacturing comes in.
Semiconductor manufacturing has created a world built on silicon. The particularly amazing aspect (and there are many) about semiconductor manufacturing processing is its unique ability to scale production and manufacturing. This is what differentiates the laser from the light bulb. The laser is the computer chip of the lighting world (with its little brother the LED). Lasers can be manufactured in ways that rival the best cellphone camera, microprocessor or accelerometer. Semiconductor manufacturing is a batch processing technique so individual lasers can be assembled quickly and inexpensively in much the same way millions of microchips are built each year. Vacuum tubes died with the advent of the transistor and so too shall the light bulb.
So this is why the laser (and we are already seeing it with LEDs) will emerge as the new standard in for illumination. Lasers to the future!
Step 3: Lasers
Laser's aren't toys!... no wait... maybe they can be? As Ralphie's mom might say, "You'll shoot your eye out!" I think we all understand by now that lasers and retinas don't always play nice but that doesn't mean we still can't have fun with our Red Ryder BB gun.
The lasers used in the project are not the kind that will light matches, pop balloons, or cut 007 agents in half. They are low power and relatively harmless (check out the links at the bottom for more safety info). Lasers can be a lot of fun if you treat them with respect! Even with that said, read about laser safety, understand the risks, maybe lasers aren't for you but then again maybe with just a little more research and experience you'll see you can still have fun while being safe!
Common features and how to buy?
- Lasers come in many shapes, sizes, powers, and colors (wavelength).
- Understand that most "lasers" you can buy are "laser modules" rather than just the pure laser diode.
- Always go with the "laser module" which includes housing, collimating lens, and driver/current controller
- The component in a laser pointer is a "laser module"
- Lasers are rated for optical power not electrical power so when you see a 5mW or 10mW laser module its referring to the amount of light being produced rather than the amount of electricity being consumed.
- In a circuit, a laser is acting just a like a diode, in other words, treat a laser module just like you would treat an LED
- Red laser technology is more mature than green and blue. As a result, red lasers tend to be lower cost, smaller, and more efficient than green or blue.
Laser Ball laser specifications (from Aixiz):
- 650nm (RED)
- 5mW (optical power)
- 20mA (this is comparable to any modestly bright LED)
Check out these links for more information on lasers:
Step 4: Diffraction Grating
Diffraction gratings are a wonderful pieces of optical technology. They allow us to manipulate light based on its wave properties (rather than the particle or ray properties). The classical physics demonstration of diffraction goes something like this: send a beam of light at a dual-slit structure (two small holes) so that as the light passes through it diffracts and creates an interference pattern characterized by bright and dark regions, akin to the peaks and valleys of a wave. Diffraction is most pronounced when the object the light is striking has similar dimensions to the wavelength of the light, if we consider the wavelength of red light is around 650nm then the microscopic diffraction structure is tiny, we're talking sub-millimeter (micron) to get dramatic effects
What's a diffraction grating?:
So if you want to diffract light, you need a diffraction grating. Perhaps the easiest way to visualize a diffraction grating is to think of a picket fence, except many orders of magnitude smaller. It's a periodic structure (which just means its repeating along its length) and so if we shine light through the slits in this picket fence, the passing waves will interfere and add and subtract to create a unique projection pattern. By changing the period (frequency) of the posts in the fence then we can also change the intereference pattern as well. This is metric is often mentioned as the number of "line pairs/inch"
Where do you see diffraction?:
Diffraction is all around us, the most common place you've probably noticed it is on the surface of a CD or a hologram. The rainbow of colors is created by the diffracting surface composed of tiny ridges and troughs. Recently there's been an emergence of rainbow glasses that create a sort of "color explosion" when you look at light sources. Those are simply thin pieces of diffraction grating with small ridges that have been most likely embossed onto the plastic surface. You also might have seen "star" caps for laser pointers. These are also small pieces of diffraction grating that have been glued into a laser pointer cap.
Why is it in the Laser Ball?
Why have just one beam per laser when you can have many? It's a laser party so bring your friends! The diffraction grating will distribute the optical energy from the laser into different spatial frequencies so rather than just creating a beam directly on-axis, multiple beams are created at specific frequencies (i.e. angles) matched to the periodic structure of the grating.
Check out these links for more information on diffraction gratings
Step 5: Teensy
I think everyone agrees that Arduino has forever changed the landscape for DIY, makers, hackers, artists and engineers. It didn't take long after hearing about Arduino before I had one and was making LEDs blink and motors spin. But it took me awhile to realize there were other options out there, ones that were nearly identical to the Arduino (and in some cases better) but in much tinier packages... welcome to the world of the Teensy! (by PRJC)
What's a Teensy?
It's a small breakout board for an Atmel microprocessor, just like an Arduino... in fact they are so alike you can run a Teensy as a Teensyduino and use the Arduino IDE, making it easy to incorporate into any project. The biggest difference you'll notice between the two is the fact that the Teensy is way smaller!. The Teensy uses the 16Mhz Atmel 32u4 chip which has the nice feature of including a built-in USB port, which enables a very compact form-factor.
What will the Teensy do?
In the Laser Ball the Teensy will allow us to take the input signal from the IR remote through the IR reciever, decode the results, then sequence/animate the lasers. This is really a bonus feature (along with the IR remote), that really makes the laser ball an entertaining piece of technology.
Check out these links for more information on Teensy:
Step 6: Battery
Battery technology comes in a lot of different varieties but the kinds that run your smartphones and ipods are the rechargeable lithium-ion variety. I'm no battery expert but for consumer-style electronics it seems this is the only way to go. Just be careful with the charging method because no one wants a flaming battery on their hands...
How to pick the battery?
Of course the Laser Ball could be driven with another style of battery but it's important to weigh out the characteristics and make a smart decision based on different trade-offs they offer. Let's think through the important factors in choosing a battery for the Laser Ball.
- It needs to fit in a tennis ball
- It needs to provide sufficient voltage (3.3V-5V) for the Teensy
- It needs sufficient capacity (amp-hours) to provide a reasonable battery life
- If needs to have a large enough discharge to provide sufficient current for the lasers and Teensy
- It needs to be rechargeable... trying to remove the battery pack from a fully-assembled laser ball is like trying to machete your way through a tropical jungle... bad joke, i know, but I think it paints the right picture.
I chose to use the 3.7V 850mAh Polymer Li-ion Battery from Sparkfun so lets see why...
- It will just barely fit in the tennis ball
- 3.7V gives me enough voltage for the lasers (3.2V) and the Teensy (3.3V)
- Its 850mAh capacity means a couple hours of battery life are possible if the Laser Ball draws ~300mA (850/300=2.8hr)
- It's max discharge rate is 2C which will provide enough current to run the Laser Ball. The C-value is just the capacity divided by an hour, so in this case a 2C rate is equivalent to 1700mA. The nominal discharge rate is 0.2C which is 170mA so the Laser Ball requirement (300mA) sits nicely within this range.
Keep it simple and buy a basic Lithium-ion charger. There are lots available in the open-source community. They are simple circuits that can regulate the charging conditions for the lithium-ion batteries and provide a nice simple USB interface. Try this one from Sparkfun: LiPo Charger Basic
Check out these links for more information on battery technology and lithium-ion batteries:
Step 7: IR Remote Control
Frankly I don't know much about Infrared (IR) remote control protocol... there's a long history going back to our old friend Tesla and his work in radio technology... but before the Laser Ball I'd never built a remote control system. So what did I do?... I turned to the web and the open-source community to see what people had been sharing... and there's lots!
And what did I learn? There are plenty of other remote interfaces like blue-tooth or wifi but frankly I don't think IR can be beat for its simplicity, low cost, and ease of use. The IR remote control interface works simply by detecting sequences of light pulses produced by the IR LED and detected by the photo-sensitive receiver. Basically each button is represented by a string of 1's and 0's (either the LED is ON or OFF) and the string represents a code word that can be identified in software. Check out the resources at the bottom of this step for more resources and tutorials on IR remote control systems.
Why does a Laser Ball need a remote control?
Well I guess technically the Laser Ball doesn't need a remote, but it adds a nice bit of functionality to compliment the Teensy. A simple push button could serve the same purpose but I hesitated to go down that path because if it were mounted on the surface of the ball I'd think there'd be a fairly high risk of damage during games of Laser toss and accidental button pushes during Laser Ball juggling.
Choice of IR remote and IR receiver?
There's no right answer for this. Adafruit and Sparkfun both have options for IR remote control. The Adafruit remote looks like its intended for a car stereo system but that doesn't mean it can't find its way into any project. The IR receiver and remote are a great combination but have two main limitations: 1) The receiver needs to be in the line-of-sight of the remote (which is true of any IR remote control system) and 2) As I mentioned the remote is most likely intended for use in a car, so the output power of the LED is relatively weak and as such the system range is limited to short distances (a couple of feet in most cases).
Adafruit IR remote control specs:
- Mini remote control with 21 buttons
- 38KHz NEC code output, 940nm IR LED
- 40mm x 86mm x 7mm (3.4" x 1.6" x 0.3")
- Runs on CR2032 battery, included
Adafruit has some great tutorials on the fundamentals of IR remote controls. You could certainly develop your own software libraries to decode the signals coming from your remote... but we are living in an open-source world so why not get a head start by using the resources we have available. That's exactly what I did when I found Ken Shirrif's IR remote control library for the Arduino (link). It worked great "out of the box" and within a couple of minutes I was able to test out functionality on a simple breadboard circuit. I liked it so much I ended up incorporating it into the Laser Ball source code. Go team!
Check out these links for more information on IR remote control:
Step 8: Tennis Ball
Tennis balls are a great little piece of hackery. Imagine all the things you could use a tennis ball for? If I type "tennis ball" into Instructables I get over 5000 hits, which is pretty amazing for an unassuming fuzzy ball. Tennis balls aren't just any old rubber ball ... they have standards. The "official" tennis balls have guidelines on diameter (65.41-68.58 mm) and weight (56.0-59.4 g) and undergo "bounce" tests (a 53in bounce from a 100in drop ain't bad!).
Why not a bigger ball?
Hey I got an idea!... pick a bigger ball and you can fit more lasers in it! Imagine a Laser Basketball... or a football... whoa!... let's save those for a future build. The choice to use the mild-mannered tennis ball was not my first choice, I admit. I built several early versions with a dollar-store foam ball, but then it hit me... I want a ball with standards! The tennis ball is so universal that I thought I would be a good metric to gauge not only this Laser Ball but any future generations that it spawned., plus the tennis ball has the right kind of "feel," just ask any juggler or Poi practitioner. And on top of that I like to think of the tennis ball as the "bottle" to my laser "ship"... full steam ahead!
How does everything fit in there?
What goes on in the Laser Ball stays in the Laser Ball... I made a quick and dirty Google sketchup model of the Laser Ball and frankly there's not a lot "free space" in there! Honestly, looking at that picture how not sure how it all fits in there... but it does!
Check out these links for more information on the tennis ball... wait, it's just a a tennis ball... what else is there to know? Find out!
Step 9: Assembly
The assembly process is very straightforward and succinctly demonstrated in the video. The following steps basically walk-through the process shown in the video. I've also included some helpful hints at the bottom of this section which highlight some of the challenging areas.
- Download and install Teensyduino software (link)
- Download Laser Ball source code and upload to Teensy (link)
- Charge Polymer Lithium-ion battery
- Disassemble laser modules
- Three-hole-punch diffraction-grating (~6.3mm dia.)
- Insert diffraction-grating pieces into laser module caps and reassemble
- Mark laser holes in tennis ball with masking tape guide lines and marker (14 laser holes)
- Dremel laser holes into tennis ball (~8mm dia.)
- Clean tennis ball (not shown in the video)
- Mark and cut main opening (~2.5 in)
- Insert battery
- Thread lasers and label their position (but don't press them in yet)
- Cut IR receiver hole (~5 x 7 mm) (not shown in the video)
- Solder wire leads to IR receiver
- Thread IR receiver
- Solder lasers to Teensy
- Solder IR sensor to Teensy
- Solder JST connector to Teensy (+5V and GND)
- Wiggle Teensy into tennis ball
- Focus the lasers by adjusting the screw cap (not shown in the video)
- Press lasers into laser holes
- Connect Teensy JST with battery JST to turn on the Laser Ball
- Wiggle JST connector into tennis ball
- Use remote to change Laser Ball patterns
- Impress your friends!
- The three-hole punch will get jammed on the diffraction grating frame so cut out the diffraction grating from the frame before three-hole punching.
- The diffraction grating sits between the lens and the cap not the lens and the spring.
- The Dremel tool is probably not the ideal way to cut the tennis ball. The rubber will tend to melt if the grinding cone is spun to fast. The tape will help prevent this and avoid gooey tennis ball from splattering all over the place.
- It's helpful to mark the hole locations with marker and the laser leads (with tape and marker) in order to try and cut off as much wire as possible and to figure out how you want to split them onto the Teensy.
- Split the laser positions into hemispheres in order to solder them intelligently and avoid wire blockages.
- Split the laser ground leads onto two busses to avoid a big solder blob.
- Solder the V+ leads of the lasers to any of the Teensy I/O pins. The pins can then be 'activated' in software. I soldered the fourteen lasers to pin#'s 4,6,7,8,9,10,12,13,14,15,16,21,22,23).
- Solder the IR receiver to one of the interrupt pins on the Teensy (pin 5,6,7,8) to use an interrupt to detect the IR remote rather than just continuously polling the receiver.
- The recommend making the main opening slightly larger than your battery width to give more room for squeezing-in wires.
- Put the battery in first! It will be extremely difficult to get it in there if the laser wires are in the way.
- Don't press the lasers all the way in before inserting the Teensy. You will probably break a lead
- I used some hotglue, rather than heatshrink/tape, to isolate the solder connections on the lasers and IR receiver and to strengthen the solder joints
- There's really no easy way to get the Teensy and leads into the tennis ball. Take your time and try to avoid putting to much stress on the components.
- Make sure to insert the Teensy with the USB port near the opening in case you want to reprogram it later.
- I used JST connectors as a physical switch but there's probably a way to make this more compact.
- Turn on the laser ball while trying to press in the lasers to see if you break any leads. That way you can fix it before you're stuck with a laser ball with a broken laser.
- Focus the lasers before pressing them in. The lens must be positioned using the screw cap/spring. I used a bit of hotglue to hold the cap in place after focusing.
- There's probably a nice way to seal the main opening but I've basically left it as a seam in order to gain access to the guts in the future
- I'm not sure what the best way is to reprogram the Teensy after its been inserted. Accessing the USB port is fine but pressing the reset switch is not.
- Test the Laser Ball after soldering but before inserting the Teensy and lasers. The earlier you catch any dead lasers the better.
- To recharge the battery: remove the JST connectors from the tennis ball, disconnect the battery from the Teensy JST and plug into the Li-Ion charger JST. Then plug the Li-Ion charger into a USB port/charger with the appropriate USB cable.
Step 10: 5-min Laser Ball
Maybe you've got a laser pointer and tennis ball but not all the other goodies, well don't fret, you can still have yourself a Laser ball in a matter of minutes. This is a min-Instructable on how to build a basic Laser Ball from a laser pointer, some AAA batteries, a bit of wire, copper tape, electrical tape, and of course a tennis ball.
- Soldering iron
- Hobby knife
- Remove the laser module from the pointer with two pliers by using a twisting motion
- Unscrew cap and housing
- Remove the switch
- Solder switch leads together (you could also just tape the switch down)
- Solder some wire to small pieces of copper tape
- Attach the other ends of the wire to the V+ and V- leads on the laser module
- Use a longer strip of copper tape to connect the V+ and V- terminals on the two batteries
- Cut a hole for the laser into the tennis ball
- Cut a slit for the battery pack into the tennis ball
- Thread the laser leads through the tennis ball
- Connect the copper tape to the open battery terminals and use electrical tape to make a small battery pack
- Tuck the battery pack into the tennis ball
- Shine on!
Step 11: Photographing Lasers
Laser Ball? Check. Point-n-shoot camera? Check. So now what? How do you capture the laser-awesomeness? There are basically two ways I know to photograph laser beams: 1) Use a fog machine or 2) Use a long-exposure setting on your camera and a piece of white paper/card. I think most people have seen long-exposure light painting, which can work just the same with lasers. But the difference with lasers is the question: how do you capture the razor-thin beam of light and not just the flare from the source?
Fog machines are fun...:
You don't need an expensive fog machine to capture a laser beam with a short exposure. The fog machine I used came from grocery store of all places... in the Halloween isle! The fog will create microscopic particles that cause the laser beam to scatter in all directions, some of which find their way into your camera. With fog you can keep the exposure short which is great for capturing video but you'll want to dim the lights in order to pull the beam out of the ambient light background.
Long exposure with a piece of paper:
The idea here is to position a scattering/reflecting surface (a simple piece of white paper works great) in front of the beam and uniformly move it down the length of the beam during a long exposure shot. If we think about it in a discrete-sense, we are imaging little slices of the beam as the card reflects the laser spot. By moving the reflector and keeping the laser beam in a fixed position we assure that the reflector will be blurred (almost ghost-like) and the laser beam will dominate the scene.
It's pretty simple: turn up the exposure to several seconds (this is often labeled as -2 to +2 in terms of f-stops on point-n-shoots) and lower the ISO setting to avoid grainy images. Normally you'd turn up the ISO setting in a dark environment to capture more light but this will create unwanted graininess in the dark regions of your images.
Step 12: Behind the Scenes, Making Of...
- I made my first Laser Ball about four months ago.
- This Instructable was made over a two-week duration.
- There were many separate photoshoots to get all the pictures.
- I shot about 7 hours of footage (for a 5min video!...)
- The video took about 2 days to edit.
- I used a standard point and shoot camera - Canon SD780 IS
- I made a cheap and dirty photostudio box from a roll of butcher paper and a piece of foam board.
- I used a 65W spotlight and a 300W bulb mounted on tripods for illumination.
- I used a sheet of white acrylic for the build surface.
- All the annotations in the images were made in Photoshop.
- I used a combination of free video editing sotware: Pinnacle Videospin (Download), Videopad (Download), and Windows Live Movie Maker. For example I did the all the cuts in Videospin, extracted stills with Videopad, and increased the video speed of the title with WLMM.
- The "Laser Ball" title uses a public font called Lynx. (Download)
- I used the Sparkfun Delux Toolkit. (Sparkfun)
Check out my blog at www.leonelabs.com
I also just want to thank the open-source, DIY, maker community. Without you guys this wouldn't have been possible.
And a special thanks to Instructables for hosting such an awesome website and service.