How can I substitute $s_x$ for Sin[x] in output to make an expression compact

Question

I have a very cumbersome expression, which I need to export to TeX form. The equations ends up to be extremely long, so I prefer that mathematica can display $\rm{Sin}[\alpha_1]$ as $s_{\alpha_1}$ , etc., and $\rm{Sin}[\alpha_1+\alpha_2]$ by $s_{\alpha_1+\alpha_2}$. Preferably, this notation will not prevent the expression from further trigonometric simplification.

I can't find a way after a lot of search. Could someone help?

Update

Thanks for the answers. They both work and have solved my problem, but I notice that they can no longer be further trigonometric simplified; for example,

 Simplify[
   Sin[Subscript[α, 1]]^2 /. Sin[x_] :> Subscript[s, x] + Cos[Subscript[α, 1]]^2]

does not simplify to 1. I wonder if there is anyway that avoid this problem? If this is possible, then the outputs within Mathematica itself can be more compact, and can be used for further manipulation, which is helpful.

Answer 1

Also:

ClearAll[toSubscript]
toSubscript = Block[{Sin = Subscript[s, #] &, Cos = Subscript[c, #] &}, # ] &;

toSubscript[{Cos[Subscript[α, 1]] + Sin[Subscript[α, 1] + Subscript[α, 2]], 
        Cos[Subscript[β, 1]] +  Cos[Subscript[β, 2] Subscript[β, 3]]}]

Answer 2

One easy way to accomplish this goal is to use a simple replacement rule.

{Sin[Subscript[α, 1]], Sin[Subscript[α, 1] + Subscript[α, 2]]} /. 
  Sin[x_] :> Subscript[s, x]

Answer 3

In these cases I like to use $Preprint:

$Preprint = # /. Sin[x_] -> Subscript[s, x] & 

This does not alter the internal representation of the expressions, just the way they are displayed.