So I got my first polarisation filter today. Linear polariser camera lens and have been playing around with it.

I have found that all the smartphones I have which use glass screens are linear. Those which use plastic screens are elliptically polarised. The application of a cheap plastic screen protector on a glass screen produces elliptical polarisation.

Been buying tools for phone surgery, so hopefully in a few days/weeks I might be able to remove the polarisation layer from an OLED phone and see if I find it more tolerable.

    tfouto

    If it dims but does not blacken whilst rotating a linear filter, its elliptical. Its difficult to explain why without giving a trig lesson.

    Linear polarised light is light which only oscillates on one axis.

    Circular polarised light oscillates on two axes 90degrees apart.

    If you plot that on an X-Y graph over time it draws a circle.

    Now if one of the two waves comprising circular polarised light is bigger than the other it won't draw a circle, it will instead draw an ellipse. Producing true circular polarised light is actually quite tricky because the separated waves have to be at the exact same magnitude.

    Bringing this back to using a linear polarising filter to detect elliptical polarisation. At some angle it will block the smaller wave, 90degrees later it will block the larger wave but let the smaller one through. So as you rotate the filter it will dim a bit but never blacken for elliptical polarisation as one the waves is always passing through.

        Seagull It also depends on the filter itself. With some sunglasses it almost dim everything, with other dim less. So it depends on the filter itself, the strenght of filter.

        Where did you bought your polarisation filter?

            tfouto

            I bought camera filter lenses from ebay. Both a linear and circular filter, though I only have the linear at the moment.

            Using my LCD computer monitor as a reference, it doesn't quite block all the light, instead reducing the transmitted to a very dark blue

              2 years later

              Did polarisation work for anyone? If so, how? I notice iPhone 8 and polarised sunglasses are way better than without

              When I wear polarised Raybans, or even non polarised and used iPhone, it's certainly better

                a year later

                Hi! To bring some new info to this thread, there's a post below from russian-speaking hardware forum ixbt.com
                It is google translated so sorry for readability.
                This guy wrote a post about specific monitor model.

                There is a clever way of sharpening, patent WO1996007115A1 - Improved polarizer (improved polarizer). The polarizer consists of many small waveguide cones. Which allows you to improve viewing angles, contrast and sharpness!. The light from the monitor is not solid (scattered, as in real life), but thin rays (10-40% of the size of the subpixel). The brain is not able to distinguish these rays, but the eyes catch, which leads to their tension. Such cone polarizers in various configurations are now commonly used. I changed the polarizer from "improved" to normal - the eyes get tired much less. Without sharpening, the text looks unusual, you need to look a little closer, but the text itself looks like in a book, without unnatural clarity. But with an improved polarizer I can read from a meter, I see everything, although I shouldn't, it's too far and shallow. The eyes have to pay for such clarity. Oddly enough, in some people, their eyes react to increased clarity the other way around. I showed 2 monitors to my friend, the first one with a very sharp polarizer, the second one with a moderate one, so he said that the first one had a normal text washed in the second one. The Ya. Market is full of reviews about fuzzy text, I think that's why. In monitors where there is no sharpness adjustment in the menu, it remains intact. And the differences in clarity are due to different polarizers. Patent citations:
                The present invention is advantageous to use because viewability around the normal to the plane of the liquid crystal device is improved and when viewed at high angle, the quality of the image is improved in that it exhibits better contrast and sharpness
                One advantage of placing the polarizer element and the array of tapered waveguides in close proximity is that the distance between the liquid crystal display device elements (pixels) and the array of tapered waveguides is minimized which results in an image with greater sharpness, contrast, and color purity

                Quad43 yep me too, slightly better.
                Everything that have a capacity to scatter the light slightly helps. Like tpu screen protector, mentioned somewhere on this forum.

                  This is extremely intriguing. I haven’t tried any form of polarized overlays or glasses with panels. I will be keeping an eye on this.

                    Clokwork I tried a real polarizing film from another phone above the screeen (and then a different one, and then two together), and the difference is present but very subtle, less than with polaroids or at the same ĺevel.
                    I have my doubts whether another polarizing film can redirect enough already directed light.
                    I would try overlays that can drastically scatter the light or try few different polirizers instead of original one

                      Not sure if I posted above, but I found gluing tracing paper to a screen protector, and then using it would both remove all polarisation and improve my tolerance of bad screens. Unfortunately though, it only improved my tolerance, never actually made a bad screen good.

                        Seagull
                        Thank you for interesting idea!
                        I immediately tried tracing paper and have to say its effect is weak, sonewhere near or even less than my current set of screen filters, and I even don't see screen clearly but still feel its brightness.
                        But I have huge doubts about whether any tracing paper can depolarize the light completely when the slightest details of screen are visible.
                        Have you ever seen the screen without polarizing film? I suppose every screen is completely white, including oled's. No film means no image.
                        Below is what i found about the topic in some textbook. It is google translated from russian, again.
                        I believe you can get some depolarizing effect but not a total removal. This is why it makes sense to try different screen overlays or better to repolarize the light completely.

                        "Multiple light scattering by wax paper can be demonstrated as follows. Place the paper on the page of the book. With this, you can easily see black letters. If the paper is lifted one or two centimeters above the page, the letters will blur and become practically indistinguishable. To understand this example, assume that black light is falling on your eye from the letter, which is scattered by wax paper. Here is another experiment illustrating the scattering of light by wax paper. Take a flashlight and direct its beam through the wax paper to a surface. Gradually removing the fountain from the paper, observe the size of the light spot formed by the light that has passed through the paper."

                          dev