Re: LIDAR strength?

[Luis Marques <marques@rtis.ray.com>]

"Graydon D. Stuckey" <graydon@apollo.kettering.edu> wrote:

> 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.   :-)

Don't underestimate the ability of the halogen lamps to make IR energy. 
They are not very efficient meaning that only a fraction of the power
consumed is converted into visible light.  The rest is turned into
heat.  Some of this heat is conducted out via the lamp housing into the
air and the rest is turned into IR radiation.  In fact, the IR output of
a halogen lamp (between 750 and 900 nm) could be as much as 50% of the
visible light output.  So for each watt of light that goes out, 1/2 watt
of IR is emitted as well. Regular non-halogen headlamps should be even
better at making IR energy because they are moret inefficient and get
hotter.

I don't think HID lamp would be very good at making IR energy.  They
are, after all, four or five times more efficient than Halogen lamps. 
So a lot of the power is turned into light and very little is turned
into heat or IR.  

Luis Marques
'87 4kcsq