shit, i didnt look at the pics up close until after i posted this above...do you spray your plants with water at any time while they are under the lights? i made the mistake of doing that, and got very simular burns to your pics. also, if your watering with nutes, be careful not to let any of that water touch the leaves....in my case, i have burnt leaves that way too...but that spotting, looks so much like what i had due to spraying water on leafs.