Unlock Speaker's Sight Exotic Helmet | Rahool Focussed Decoding Page 3 | Destiny 2: The Final Shape 

Visit the Cryptarch in The Tower after levelling your reputation past rank 16 and you will be able to do Focussed Decoding of Exotic Engrams. Exotic Engrams are the only way you can unlock the new Exotics right now. You will not get them from Vex Incursion or Lost Sectors!
Focussed Decoding costs 1 Exotic Engram and 1 Exotic Cipher. Do the quest with Xur to unlock the Exotic Cipher. For the Exotic Engram, I got mine from farming the Nightfall.