LIDAR strength?

["Graydon D. Stuckey" <graydon@apollo.kettering.edu>]

On Thu, 17 Sep 1998, Whitson wrote:

> Robert Houk - WorkGroup Server Firmware wrote:
> > 
> >    I have a couple PIAA 959s in my garage, they seem ideal candidates for
> >    this modification.  All metal, they should take the heat of a big bulb.
> >    Small, so smaller IR filter needed, and tidy.  How big a bulb?
> > 
> > How much power really is needed? The source laser *must* be down in the
> > milliwatt range, and must be reading microwatt levels reflected back. It
> > seems like a flashlight pointed at the source would completely swamp any
> > reflected signal, let alone requiring megawatt QH bulb assemblies . . .
> > Just kinda curious.           -RDH
> 
> If only a small source is needed, why not use superbright IR LED's ?

I am not an optical major, but my understanding of this is that the light
that is shed by a typical halogen light bulb has a small amount of the
frequency at which lidar operates.  That frequency is very high, such that
we can't see it with the naked eye.  Since halogen bulbs are designed to
produce light in the visible spectrum, they are not incredibly efficient
at producing LIDAR freq light.  So, if you use a very strong halogen bulb,
it _may_ have enough energy in that frequency range that it could blind
the LIDAR.  I have this suspicion that these new HID bulbs may just have
even more of that frequency, but I have no data to back it up - just a 
hunch.   :-)

Scott made the point that the light disperses very quickly with 
distance.   That is very true, but the reflected signal from the LIDAR 
unit also does the same, so if you transmit a signal 10 times stronger 
than that of the LIDAR, I suspect you'd have a pretty  good chance of 
blinding it.  It might at least buy you a few seconds to reduce your 
speed.  However, it might also destroy your V1's laser sensitivity...

Later,
Graydon D. Stuckey

"There's alot more to Jazz than just wrong notes"