With the advent of cheap and powerful laser diodes, possibilities abound for writing technology. Simply mount the laser inside a pen, with optics to focus the beam just beyond the end of the tip. When the pen is gripped for use, the diode emits a short, low powered burst of photons, and measures the reflected light. When the circuitry deems the pen is pointed at a suitable writing surface (not mirrored, refractive, or someone's eye), the laser switches to full power.

A mass of radiation heats the writing surface, causing it to scorch. Continuous monitoring with a photosensor ensures proper dynamic heating for even line thickness. The sensor also watches between laser pulses for evidence of chemiluminescence, otherwise known as fire.

As this pen uses no ink, it does not smudge, and can be used on a wide variety of surfaces. Battery life is likely poor, but it can be plugged in for continuous use.
-- Aq_Bi, Feb 16 2012

Laser diode wood burning pen http://www.instruct...r-wood-burning-pen/
[ldischler, Feb 16 2012]

"For best results avoid event horizons"
-- Ling, Feb 16 2012


sp. Battery life is nonexistent, and it has to be plugged in for use.
-- MechE, Feb 16 2012


Ever write a note on the palm of your hand?
-- DIYMatt, Feb 16 2012


//Battery life is nonexistent, and it has to be plugged in for use.//

Not so. A 1W blue laser diode (which would work, but slowly) uses about 2W of power. You can get AAA batteries with a capacity of about 1000mAh, which equates to about 40 minutes of lasing time.
-- MaxwellBuchanan, Feb 16 2012


[MB] Only very slowly. I was figuring on normal writing speed and normal writing motions. Plus operating the driver, and all the feedback mechanisms mentioned.

As an aside, you're going to have wicked cooling requirements or severe duty cycle limitations.
-- MechE, Feb 16 2012


//As an aside, you're going to have wicked cooling requirements or severe duty cycle limitations.//

That was my problem with the idea too. But then some people have never played Mechwarrior. Anyone who has knows about lasers and heat buildup. And you can't really put a two ton heat sink on a pen.
-- Psalm_97, Feb 16 2012


//Ever write a note in the palm of your hand?//

Yes, yesterday: Happy Valentines Day!
-- rcarty, Feb 16 2012


[MechE] Well, OK. A 10W diode will probably do the job, giving you 4 minutes of continuous lasing from a AAA battery. Go for a bulkier pen with 2xAA, and you've got maybe half an hour.

Plus the laser is not on the whole time - I'm guessing it's only "writing" for 50% of the time it's in use, so you have an hour. The power consumption accounts for the waste by the driver, too.

Cooling, yes, a problem. With a 10W laser, you'll also have about 10W of waste heat to dissipate. Ideal for writing in cold climates! Or build a tiny fan into the pen for forced-air cooling (which will knock a little more off the battery life).
-- MaxwellBuchanan, Feb 16 2012



random, halfbakery