buzzeroo

Ok, well that makes me feel better. It does only occur on very bright sunny days and just when the sun is positioned just so. I was alarmed as the first time i noticed it was when pulling out of the tint place.

Thanks for the feedback.

Iceman

When you have it again, move your head - the glare will dissappear or at least will be different. I am pretty sure it's a reflection of sunlight falling in to the HUD.

Rudy

I agree with Iceman. I knew why he was asking the "blue" question and was waiting to hear the answer before I chimed in.

I've seen a blue glare only if the sun is at a specific (rare) angle. In my case, it happened when I had the sunroof open. The sun was behind me just enough to come in through the roof and hit the HUD just right. It was at a red light and once I was underway, the car moved enough to stop the glare. Rest assured that 99.9% of the time, I don't see the glare.

Also, rest assured that unless you tinted the windshield, polarized tint shouldn't make a difference.

JDN

Hey, Rudy/Ice, you guys have been holding out on me. I wanna see blue, too -- never have. I know. I'll put on my blue glasses.

sg530

Looks like I have pull out the deadly scientific stuff.
The modern displays with LCD's work with polarized filters to allow the LC's to make a light or dark spot with an electric pulse. The HUD is an LCD image projected onto a reflective windscreen. If you wear sunglasses that are polarized, it kills the HUD image to nearly zero. If you tilt your head, the image returns because the polarization of the glasses no longer cancel the polarization of the display. So far, most of you know much of this physics. Sunglasses are made for reducing glare from objects and water outdoors. The best results occur when the orientation of the polarizer is horizontal or close to that. Why?
Now the science....because the light from the sky on a sunny day is itself polarized. If you look at the blue sky with the polarizer filter, you will see that parts of the sky will be darker than others, until you rotate the polarizer and the darker part moves. Thus, as you drive around on a sunny day, the angle of polarization of the sky 'light' relative to your window changes as you go north south east or west.
This is why a polarizer filter is standard for photographers outside to improve the picture. I see it on tv videos all the time too.

Rudy

Fine but I still don't see how putting polarized tint on the other windows will affect the HUD display...

sg530

Polarized tinting would filter the sunlight comming through and that is what changes with sun position. At some angle, the light falling on the optics of the HUD will be polarized 'the wrong way' and make a glare off the HUD viewglass windows very pronounced. The 'blue' glare color (on mine it is a little more purpleish) is the light reflected into and back out of the outermost mirrors and window of the HUD in the dash which, along the way becomes mostly bluish. There are coatings on the optics to keep heat from the sun out of the system. The hot color of the solar spectrum is red-infrared. This leaves blue-indigo to go through the optics easier and thus become the stronger color of light coming back out. The light path for the glare is completely different from the image generated by the LCD display.
If polarizing tinting were put on the windsheild inside, it would have affected the HUD a lot unless its orientation was 90 degrees from that of sunglasses. This is unlikely the case, but easy to check with polarizing sunglasses from inside the car. This is why I don't think the tinting is polarizing by design but by accident in its manufacture.
More science: the lamination of plastic with glass that makes the windsheild structure also polarizes the the sunlight a little. That is why when looking at windows of other cars with polarizing sunglasses, they have that 'pattern'; you know what I am saying.
Without seeing the effect in person, the explanation remains speculation.

alohalc

sorry for the late welcome, buzzeroo . anyway, sg530 or mr. einstein , very impressive .

kigerka

Never noticed blue either. I guess I need the glasses

buzzeroo

sg,

Thanks for all the great information. Let me see if I understand correctly. It sounds as if the tint I have placed on all windows (except windshield) may be causing the blue glare seen from time to time. Would this happen if the tint was not a polarizing tint? (i think my tint is llumar but i have no idea if it is a polarizing tint or not... i'll find out and post when i know).

Iceman made an earlier comment that he occasionally sees the blue glare and he does not have window tint. What would explain that?


Thanks again.