user18441: A 32 inch flat screen was embedded in a coffee table and covered by a protective layer of glass. Sensors around the edge of the glass surface need to be able to detect the precise location of an object on the glass so that a mouse cursor can be controlled with a stylus.
What sensors would you use to ensure accuracy of stylus location above the screen?

user20245: Perhaps if you drop the monitor an inch or 2 away from the glass you can use a Frustrated Total Internal Reflection (FTIR) IR scheme.  But at that shallow angle it will be tricky and may require several cameras around the edges. 

added later...  
Should mention the parallax problem given there is a gap of an inch or more between the monitor and the touch screen.  FTIR is better when you project the image onto the touch screen.
If you don't mind lower resolution, I believe the micro dose dispenser soda machines use a capacitive touch wire mess embedded in the transparent plastic front panel.  Although micro dose dispensers appear to only need to emulate about 100 to 200 buttons.  Not enough to control a mouse with any accuracy.  But enough to control a GUI designed with such constraints.
Loose high resolution capacitive touch screens can be bought with out a monitor.  However they tend to be much smaller then 32 inches.

18441: <p>A 32 inch flat screen was embedded in a coffee table and covered by a protective layer of glass. Sensors around the edge of the glass surface need to be able to detect the precise location of an object on the glass so that a mouse cursor can be controlled with a stylus.</p>

<p>What sensors would you use to ensure accuracy of stylus location above the screen?</p>
 20245: <p>Perhaps if you drop the monitor an inch or 2 away from the glass you can use a Frustrated Total Internal Reflection (<a href="http://mmu.ic.polyu.edu.hk/mu_proj/2011/IPD/IPD04/Research.html" rel="nofollow noreferrer">FTIR</a>) IR scheme.  But at that shallow angle it will be tricky and may require several cameras around the edges. </p>

<p><a href="https://i.stack.imgur.com/0mnrG.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/0mnrG.jpg" alt="enter image description here"></a></p>

<p>added later...  </p>

<p>Should mention the parallax problem given there is a gap of an inch or more between the monitor and the touch screen.  FTIR is better when you project the image onto the touch screen.</p>

<p>If you don't mind lower resolution, I believe the micro dose dispenser soda machines use a capacitive touch wire mess embedded in the transparent plastic front panel.  Although micro dose dispensers appear to only need to emulate about 100 to 200 buttons.  Not enough to control a mouse with any accuracy.  But enough to control a GUI designed with such constraints.</p>

<p>Loose high resolution capacitive touch screens can be bought with out a monitor.  However they tend to be much smaller then 32 inches.</p>
