Scanning simultaneously across 2-dimensions electronically (like a "3D oscilloscope")
As far as I know, this already exists.

Many analog oscilloscopes have what is called a "Z" input.  This modulates the brightness of the spot.  You use the X and Y inputs for your two axis, and the laser intensity goes to the Z input.

Then there's this:



That's an image made by aiming an antenna (X and Y coordinates) and recording the intensity of the radio waves received.  The bright blob is the moon.

You can do the same with your two laser control voltages.  Scan them both, and record the intensity for each XY combination.

So, kind of like 2.5 dimensions.

Alternatively, go full on 3D.  Columns in a cube.  X and Y are your inputs, height of the columns are intensity and go in the Z direction.




Use three channels on your digitizer.  
Record laser input 1 and laser input 2, as well as laser intensity 3.
Use whatever method you like to control the digitizer and record the values.  Some have a simple program that records to CSV files - you could use that.
Use something like Veusz to read the CSV file and make images.


I used Veusz to make images like that several times.  The moon image above was produced in a similar way.