[opendtv] Re: How small can video cameras become?
- From: Doug McDonald <dtvmcdonald@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Mon, 14 Jun 2004 11:59:26 -0700 (PDT)
--- Mike Enright <menright1@xxxxxxx> wrote:
> olivier houot wrote:
>
> >Henry baker wrote :
> > >How good can such a small camera be? Is the size
> of a
> > >video camera constrained by physics to be some
> minimal
> > >size, or could a broadcast-quality video camera
> (e.g., HD)
> > >someday be embedded into a cellphone?
The laws of physics are very simple. We assume
we want a visible light camera, of course.
The resolution is limited by diffraction. A reasonable
lens is f/1 (that's a one). Such a lens has a limiting
resolution such that a pixel 0.5 micron across is
appropriate. To get color, we need of course three
sensors for each pixel (for broadcast quality). These,
however, are not constrained by diffraction and we can
squeeze all three, and their filters, into a square
0.5 micron on a side. A chip with a resolution of
1080x1920 pixels (not oversampled) would therefore be
about 1 millimeter across. Making a diffraction
limited
normal or wide angle f/1 lens covering a 1.15 mm field
is easy.
Thus a broadcast quality (with no oversampling)
camera could be made to fit in a space perhaps 2x2x3
millimeters. Of course, the cable to it would be fun,
and no zoom lens. And, since it used color filters
rather than three sensors and prisms, it will need
a goodly amount of light for broadcast quality.
Doug McDonald
=====
Doug McDonald
my last name at scs dot uiuc dot edu, not here at Yahoo, please
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