Laser ranging system

I also wonder if any of VEX users would also like to use a laser-ranging system (uses lasers instead of ultrasound). I am planning to make one of my own (I do have all the knowledge and resources). So far, i just did a couple of tests with a laser beam (laser diode, 650nm wavelength, <5mW). I have found that it that it does reflect off of objects (such as walls) with the help of a magnifier glass lens at the receiver end to magnify the laser reflected. The hardware config. would be much like the ultrasonic rangers, but it will use lasers instead. heres one example of a application that uses lasers: The application.

Oh, and heres another example: another example.

Also, one of my dad’s friend told me that in Japan, when a fiber-optic under-sea cable is broken, they send a laser beam in to the fiber optic and wait for the beam to reflect off of where the fiber was cut, and travels back to the origin of the laser beam, and timing it in between to figure out where it was broken.

That would be amazing!!! It would be much cooler if you built the bot and showed it of to other members. I would still use the vex range finder to show off to younger kids because they would totally freak out. Post pics if you decide to make this.

Unfortunately, it will be some time (dont know how long) before this can be built. I am still trying to get an LCD (non-VEX related) to work, then i can make the laser ranger. I hope the LCD will work soon…I am also very excited about this.

here are some of the possible advantages/disadvantages of using this:


  1. Uses less parts
  2. possibly that the laser diode and photo diode can be water-proof.
  3. more acurate
  4. travels a greater distance
  5. there are no crystal driving the laser diode (except one for the on-board controller), so there will be no “aging” of the laser diode/photo diode.


  1. laser diode/photo diode are more sensitive to ESD.
  2. maybe a little more pricey.
  3. can cause damage to eye (the laser will only be on for less than 500us possibly).

it also would be a lot faster. If you’re building a robot for speed, and you have an ultrasonic rangefinder programmed on it, the robot will sometimes be going so fast that the sound doesn’t travel back fast enough and the robot won’t have enough time to react. With a laser, however, you could have way more precise movements with your robot.

One question: Would InfraRed work?

infared can be less reliable, usually depending on the surface it’s reflecting on

AND, one more advantage is that it could also be possibly operable in a place where there is nothing (no air, atoms, etc.), such as space.

oooh, that sounds cool, any1 wanna launch their vex robot into space!?!

lol…just kidding…although…

What kind of robots do you build that can go faster than the speed of sound?

lol…ummm…a robot that can go to Mars? lol im just kidding. If we cant build a robot that travels faster than the speed of sound, then we can use the other advantages (such as the laser beam can travel farther)

well not speed of sound but robofreaks robot went over 50MPH, which is pretty amazing

Hooray! I got the LCD done, now im just one step closer to working with the laser.

great, could you post code and pics?

Wouldn’t the laser light travel too fast to time?


possibly but i would be sending out pulses pretty rapidly that you’d getjust an accurate reading, there’d be some serious calculating involved

I mean… Instead of timing how long it takes to come back. You would probably want to send out the laser pulse and measure the angle it comes back at.


As i said, it’s unrelated to VEX, but anyways, here it is: (picture in attachments)

The controller i used was a OOPIC ( And the LCD i used was from B.G. Micro (

the code:

Dim LCD As New oLCD

Sub Main()
LCD.IOLineRS = 14
LCD.IOLineE = 15
LCD.IOGroup = 3
LCD.Nibble = 1
LCD.Operate = 1
LCD.VString = “Over one year of”
LCD.Locate (1,0)
LCD.VString = “debugging, IT WORKS!”
End Sub
IMG_1359 (Large).jpg

Your using a independent power supply, right?

one year of debugging!!! i used my lcd (the parallel type not serial) with my basicx and basic atom, took me about 10 minutes, my serial one took about 3

If i know what your saying, its hooked up to a powersupply (away from the vex), and its part of a separate project

lol…total, i have bought 3 parallel LCD’s, and 2 attempts. The first attempt, the data sheet has some “un-mentioned” specs, so that lcd has been trashed. what i mean by “un-mentioned”, is that the sheet says it has a total of 14, but the LCD had 16, so i assumed the inner pin was 1, WRONG. before the first pin, i found small lettering on the board “K” and “A” (for the back-lights). On attempt 2, (I am clumsy, plz dont laugh) I had mis-wired the whole thing (due to my clumsiness). About a month later from the second attempt, i re-checked my wiring and found that all are wired backwards. I corrected the LCD’s, and yay, it worked. the first LCD i bought was from jameco (mfg.: Hantronix, cost: $20.00), and it was trashed by lack of specs… On my second pair of LCD’s, I bought them from a surplus store costing less than $5.00. whats so surprising is that the cheap LCD (from the surplus store) is VERY durable, it can withstand shorts for a long period of time, while the costly one, is just easily broken.

Plus the fact that i have school, so i dont have much time per week to work on it.