but i said why we cant build a light detector stepwise.
No you haven't. You've only asserted it repeatedly, but you've in no way demonstrated it.
so for now lets agree that so far all the evidences we have support the claim that a light detector cant evolve stepwise.
The evidence doesn't support that claim at all. All you are doing is resorting to an argument from ignorance/incredulity. It's a weak form of argument.
If you want to demonstrate that a light detector could not evolve, you need to demonstrate positive physical barriers preventing its evolution. You continue to fail to do so.
if so link me to a specific paper. but if it will not say how many amino acid we will need to change for the evolution of the first lgiht detector then the paper is actually meaningless.
I've noticed typical creationist tactics with your posts. When you're given scientific papers where there are hypotheses or assumptions (as is the case with almost everything in science), you dismiss it as speculative. Then you set up arbitrarily strict requirements of acceptance that borderlines on the absurd.
I originally linked to those papers as sampling of literature on eye evolution, since you originally claimed there was "no evidence" for such evolution. Your claim in this regard is obviously false as there is considerable literature and investigation into the topic backed up by studies into paleontological evidence as well as molecular evolution.
At this point, I can't force-feed you scientific literature, especially given your predilection for hand-waving dismissals.
All I can say is that if you really want to demonstrate the impossibility of the evolution of the eye or a light patch or whatever, you need to point to legitimate physical barriers preventing it. Simply pointing to gaps in scientific knowledge and setting absurd goalposts for said scientific knowledge is not bolstering your case.
If anything, it demonstrates how intellectually bankrupt the argument for a intelligent designer really is.