Liquid sky effect using led light

I saw this cool effect made by using a laser, a line generating lens and a fog machine, basically it visualises the smoke giving the impression of a liquid surface.

I wanted to do the same but without a laser. 
I tried to explain the concept in this drawing.

  I thought that collimating the beam would minimise divergence, I don’t aim to project a crisp line on a wall but at least to obtain a plane-ish light beam.

I actually made a crappy prototype using cardboard and a shiny present paper, I didn’t have a good light source and I eyeballed the position of the focus.

It kinda worked but the light divergence (dispersion? Hope I’m using the right words) was too much over a short distance.

What are your thoughts on this? Do you think is doable? Is there an easier way to do this? Do you have any links I can look at that might help me? 
I saw the artificial sunlight video and I’m basically using the same principle but in “2D”.

p.s.

here is the link to a video showing the effect I want to achieve.

p.p.s.

if you are asking yourself: why don’t you use a laser?? The answer is I’m scared 🙂 also I don’t like the colours that I can buy for a reasonable price.