comma after introductory phrase [preposition]: Among... factors, the

Have I put comma on right place?

Among non-instrumental factors, the intensity of the reflected laser beam is of great importance since the range ....

I think there is no comma between importance and since. Am I right?

The comma after factors is optional, and a comma after importance is optional too, or may depend on what follows range.

Have I put the comma (削除) on (削除ここまで) in the right place?

Among non-instrumental factors, the intensity of the reflected laser beam is of great importance since the range ....

I think there is no comma between importance and since. Am I right?

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Welcome to the forum, Shahbaba!
It appears to me that a comma is probably necessary after "importance", but it is difficult to tell with only part of a sentence. If you will give us the full sentence (as the forum rules ask), we will be better able to advise you.

The comma after "factors" is optional, although it's preferable. If you read the sentence out loud, there would be pause for breath after "factors" and a comma would reflect this. I personally always insert one after long introductory adverbial phrases, but perhaps that's just my preference. As far as I can see, you don't need one after since. Consider:
1) He didn't go, because his mother was ill - His mother's illness prevented him from going.
2) He didn't go because his mother was ill - But he went for another reason.
Some people may suggest that the difference between the two written sentences is the one I've outlined. Others may suggest that the two sentences mean the same thing and you only need (2). If you uttered the words, there would be a different stress pattern depending on whether you mean (1) or (2).