Capturing infrared light with a webcam
As you may know web cameras include CCD sensors that are
capable of capturing both visible and infrared light.
Manufactures include a filter to block the infrared light, but
some of it still passes through. This is the main reason you can
see the light coming out from an infrared LED (look at the
next picture). These type of LED's are emitting infrared
light invisible to the naked eye.
If we remove the filter then more infrared light will be
captured from the webcam. We can use this phenomenon in
surveillance systems (for example watching a dark room). Even if
we light the room with infrared radiation it will remain dark to
our naked eyes (and to the intruder!).
I will describe the procedure with few simple steps.
First we will need a standard usb webcam. I selected a joker
webcam by crypto. The are two main reason for that. It's a
cheap webcam (so if we accidentally destroy it, we won't
loose a lot of money) and it's easy to hack.
Disassembly the camera. Unscrew the focusing lens until
it's completely removed
The lens is now removed
Remove the infrared filter from the back of the lens. It was
impossible for me to remove it without breaking it. Be careful
when breaking the filter to avoid destroying the lens
broken IR filter
(this filter blocks infrared)
exposed lens after removing the filter.
Notice the nice area
above the lens.
This is the place where we will put our filters
In order our webcam to
work as an infrared camera, we must replace the original filter with
another one. The trick here is to block normal light and let
infrared pass through. The best (simple and cheap) choice is
to use film negatives (from the old times
of analog photography) like the one in the picture
Cut the dark area of the
film in small squares and place them where the original IR filter
was. They must have approximately the same size as the original
use the area where the actual negative of the picture is. You will
not have the desired results.
For better results use
more than one (I used two, but it's possible to have better
results by using three). Make sure you cut the squares big
enough in order to stack inside the area of the original filter.
The first square film filter
(this will be the first
The first filter placed inside the area above the lens
The second square filter
(this will be the second layer)
The second filter placed above the previous one
Attention: Avoid touching the film with your hands and make
sure it's clean. Make sure the lens is also clean, before fitting
the squared film filters. Don't use super glue to fit the filters in
place. It may accidentally go to the lens.
Note: This was one of the
reasons I selected the crypto joker camera. It has a nice area for
fitting the negatives without the need of a glue.
In the following picture you see how things look in infrared (the
light source is a lamp which is also emitting to infrared)
Note: Notice how bright an infrared LED is (the original
filter was blocking most of the infrared light).
The same picture in a dark room. Our light source is just a TV
Seeing in the dark
In order to see in the dark we need an infrared light
source. A lamp is our first choice but it emits visible light
too (an the intruder will see it). So the next solution is
using infrared LED's
Note: Crypto joker webcam has
build in LED's, for viewing in the dark. These are ultra bright
white LED's (see the picture below) and they are not
emitting in infrared. The first thought was replace the
existing LED's with infrared ones. Unfortunately there is one problem.
driving circuit is not designed for infrared LED's, which means
they will not emit a lot of light (infrared). In my
experiments I had more light coming out from a TV remote control
(which has only one LED) even when I replaced all six of
the original LED's with infrared ones. Short-circuiting the internal
current limiting resistors didn't help much.
Unfortunately by replacing the original LED's with infrared
...will not give you the desired infrared light (even if you
short-circuit the internal current limiting resistors)
My goal here is capturing images from a completely dark room. So I
will need more than six LED's to accomplish that. So why not doing
something extreme like the
*(not uploaded yet)*