Function of lens fluting above projector?

[Ls400]

I replaced my 2012 IS350c's lamp with a new, OEM lamp from Lexus. The new one doesn't have any fluting above the low-beam projector. The old one does. What's the purpose of the fluting? To shape the uplight? Am I losing any benefit from not having the fluting? Is the function of the fluting to reduce uplight as to reduce glare from overlit retroreflective signs?

https://imgur.com/a/rSkm9rC

 

[Alaric Darconville]

What's the purpose of the fluting? To shape the uplight? Am I losing any benefit from not having the fluting? Is the function of the fluting to reduce uplight as to reduce glare from overlit retroreflective signs?

My guess is it was originally just decorative but may have, at certain angles, generated objectionable glare for other drivers. Or it was to provide some uplight for overhead signs, but (again) resulted in objectionable glare. Either lamp should have conformed with FMVSS108 (ostensibly), so it's hard to say if it is cosmetic or in response to a problem discovered later. Just guesses, though!

 

[-Virgil-]

I'm with Alaric: most likely just decorative; it's really not in the light path from the projector, and it's way too far above the projector to affect uplight for overhead signs. About the only functional purpose it could have potentiall served would be to diffuse a spot reflection from a portion of the bezel or inner surface of the lens which if undiffused might have violated the self-glare/backscatter light control region (10 to 90 degrees up, 45 left to 45 right). But that really doesn't look like the kind of texture usually used to diffuse spot reflections. I really think it's decorative.

 

[Ls400]

About the only functional purpose it could have potentiall served would be to diffuse a spot reflection from a portion of the bezel or inner surface of the lens which if undiffused

Speaking of diffusing a spot on the bezel, I noticed that my bezel just below the projector and the fluting is bubbled. This lead me to Googling headlight bubbling for my car model and down this rabbithole...maybe the spot is for diffusing light, but in the opposite direction?

https://www.clublexus.com/forums/is-2nd-gen-2006-2013/579232-2011-headlamp-bubbling-defect-33.html

http://jeff.supramania.com/is250/tsb/L-SB-0005-12.pdf

Anyhow, it seemed that the attempt at diffusion failed, because mine is severely bubbled anyway.