I have a hypothesis that polarizing film might be connected to my severe smartphone eyestrain, which is described in Light/vergence thread.
I've made some research on the topic. Info about polarizers is unavailable, there's no data in the internet.
So I collected some data myself in the retail store nearby.
I wonder if there is some connection or correlation of eyestrain with characteristics of polarizer.
Polarizing film is a layer above matrix, it is responsible for the image. No polarizer means no or little image. IPS screen is white without polarizer. Amoled screen is grey without polarizer. Polarizer makes image visible, clear, readable under the sun, etc.
There are many characteristics of polarizers, and I could check only one of them.
It is the circular vs linear polarization. This can be checked easilly with another linear polarizer or simple polaroid sunglasses (they are a linear polarizer). If you want to repeat my experiment, look through the glasses and rotate the phone left or right. Make a full circle. If the phone has linear polarizer, you will see almost or entirely black screen at some point.
If it has circular polarizer, you will see screen all the time, or you might see a rainbow on the screen.
Technology is tricky, sometimes you could see something in between.
Test Subjects: Absolutely all phones on a display in a retail store. Where there were several display items of the same model, I checked each one. The polarizer type is recorded if at least 1 phone model with this type is found. In the same phone model, there may be several types of polarizers, or one of unstable quality.
Detector: Polaroid glasses
Test image: white background chrome.
In some cases, marks have been made about the passage of light. I tried to be as accurate as possible, but it's still a subjective value. Somewhere I could detect it incorrectly.
It also seems mysterious to me that the a lot of linear (?) 45° polarizers do not completely block the light with polaroids. Perhaps different colors go in different directions. That might be important to the eyestrain issue.
Different colors go slightly in different directions on iPhones, when tilted to one side they turn bluish, to the other side they turn slightly red.
The direction of the 45 ° tilt (left or right) was not marked here, so one phone could be tilted to the left, another one tilted to the right.
Linear polarization, with an angle of 90:
xiaomi redmi 9a
realme c11 2021
xiaomi redmi 9c
huawei p smart 2021 (light is not completely blocked)
huawei p40 lite
poco pro x3
samsung galaxy a12 a125fz
samsung galaxy a12 a127f
samsung galaxy a03s
Presumably linear polarizer, with an angle of 45:
realme 8 pro
huawei p40 pro
oppo reno5 lite (light is not completely blocked)
xiaomi mi 11 lite
xiaomi mi 11 lite 5g
xiaomi redmi note 10 pro
vivo v21 (generally a lot of light remains)
vivo v21e (same)
xiaomi mi 11i
xiaomi mi 11 pro (light remains)
samsung galaxy s20 fe
samsung note 20 ultra
samsung note 20
samsung galaxy s21 +
samsung galaxy s21 ultra
samsung galaxy s21
samsung galaxy a72
samsung galaxy a32
samsung galaxy m52
samsung galaxy m32
samsung galaxy a32 (does not completely block the light)
samsung galaxy a22 (leaves a lot of light)
oppo reno5 lite (leaves a lot of light)
OPPO Reno4 Pro
oppo a74 (some light remains)
Rainbow (presumably circular polarizer):
huawei p40 lite
xiaomi redmi 10 (very faint rainbow)
vivo y20 (weak)
No light blocking, no rainbow (presumably circular polarizer):
xiaomi mi 11i
iphone 11 (there is color distortion: at 90 ° the screen is slightly yellow)
iphone 12 mini (45 ° slightly blue)
iphone 12 (same)
iphone 12 pro (same)
iphone 13 (the same when tilted to the other direction)
iphone 13 pro (same when tilted to the other direction)
iphone 13 pro max (not only bluish in one direction, but also unpleasantly red in the other)
IPad 10.2 2021 (blue at 90 tilt to either side)
Ipad air 10.9 2020 (blue at 90 tilt to either side)
Weird hybrid of linear polarizer and rainbow:
oppo a54 (and in two different versions - one phone is more like a linear and less rainbow, the second is an opposite)
Another type of hybrid, with milder blackout - vivo y20, oppo a15s
Two mysterious phones:
Samsung galaxy z fold 3, looks like circular or without a polarizer (it has some kind of filter instead of a polarizer)
Samsung galaxy z flip 3, creepy neon bright rainbow
(At some screens, the light from the lamps above reflected into the screen is decomposed in polaroids into a bright long rainbow, regardless of the polarizer, and at other screens into a small one. Have no idea if it somehow matters.)
I tried to be as careful as possible, but on such a number of phones could be 1-2 typos.
P.S. Sorry for all the mistakes in English.