Clean Canopy Glass

[Faelwolf]

On 2/16/2022 at 2:17 PM, jaylw314 said:

FWIW, I'm not sure if helmet visors are polarized to remove sun glare anymore, since they also render LCD screens visible only at certain angles.  Polarizing filters are great for removing surface reflections, but tinted unpolarized visors and glasses don't do that, they just reduce eyestrain.  Anyone know?

That is correct, non-polarized lenses will reduce, but not remove glare, more for reduced eyestrain and improved overall vision. I have a pair of polarized sunglasses in my prescription for driving, but I can pretty much forget using my phone while wearing them.

[jaylw314]

4 hours ago, Faelwolf said:

That is correct, non-polarized lenses will reduce, but not remove glare, more for reduced eyestrain and improved overall vision. I have a pair of polarized sunglasses in my prescription for driving, but I can pretty much forget using my phone while wearing them.

IIRC, the FAA published an AC a few years ago suggesting pilots forgo polarized lenses with the increasing number of digital displays in cockpits

[silverdevil]

16 hours ago, jaylw314 said:

IIRC, the FAA published an AC a few years ago suggesting pilots forgo polarized lenses with the increasing number of digital displays in cockpits

hah. my gas station got new displays and my sunglasses prevent me from seeing them very well. so this makes very good sense.

[Caldera]

Ahah  Ahah

Thanks Guys!

Caldera

[PhoenixRising]

I was also told when I started flight training that polarized glasses reduce the glint of sun off of other aircraft so it is harder to see other aircraft. That was in addition to the issue with modern screens blacking out at certain angles. I have no idea how much truth there is in this statement.

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[silverdevil]

37 minutes ago, PhoenixRising said:

I was also told when I started flight training that polarized glasses reduce the glint of sun off of other aircraft so it is harder to see other aircraft. That was in addition to the issue with modern screens blacking out at certain angles. I have no idea how much truth there is in this statement.

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LOL always that one guy that misses the memo.

[jaylw314]

53 minutes ago, PhoenixRising said:

I was also told when I started flight training that polarized glasses reduce the glint of sun off of other aircraft so it is harder to see other aircraft. That was in addition to the issue with modern screens blacking out at certain angles. I have no idea how much truth there is in this statement.

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In theory, yes.  In reality, glasses are polarized in one direction (horizontally?) to kill reflection off the ground or water in front of you, which would be polarized the other way (vertically?).  Planes can be in all sorts of directions and surfaces, so while one particular direction may have less glint, most other directions would be less affected

[Frederf]

Polarized glasses are polarized such as to permit vertically polarized light. I don't know if they're named for what they block or what they transmit. A lot of diagrams will show this as vertical stripes like it's a wiggling rope which has a "slot" to wiggle through. If you put the glass under a microscope you'll actually see the opposite. Polarization is done by printing very thin lines of conductor on glass parallel to the polarization that should be blocked. When the electric field of the light meets the glass it want to motivate the electrons to move parallel to the polarization. These moving electrons act as an antenna which gives off the canceling phase of electric field. By allowing the electrons to move left-right but not up-down the light which is polarized left-right is cancelled but the up-down polarization isn't.

LCDs work by polarization. It has a static polarizing filter and the active element is another polarization filter at right angles. The combination allows the light to be blocked when both are applied. But the light that isn't totally blocked is already polarized by the first built-in always-on filter. So you never get unpolarized (i.e. randomly or uniformly polarized) light out of it. And this will interact with glasses adversely. Airliner/private jet windows can also have non-uniform polarization effects which look clear with the naked eye but splotchy when viewed through polarized glasses.

I don't know about jet fighter canopies. Presumably they are coated because radar reflections off the cabin are bad news but that's a different wavelength. But they don't have any special displays that are non-polarized that I know of.

[jaylw314]

54 minutes ago, Frederf said:

Polarized glasses are polarized such as to permit vertically polarized light. I don't know if they're named for what they block or what they transmit. A lot of diagrams will show this as vertical stripes like it's a wiggling rope which has a "slot" to wiggle through. If you put the glass under a microscope you'll actually see the opposite. Polarization is done by printing very thin lines of conductor on glass parallel to the polarization that should be blocked. When the electric field of the light meets the glass it want to motivate the electrons to move parallel to the polarization. These moving electrons act as an antenna which gives off the canceling phase of electric field. By allowing the electrons to move left-right but not up-down the light which is polarized left-right is cancelled but the up-down polarization isn't.

LCDs work by polarization. It has a static polarizing filter and the active element is another polarization filter at right angles. The combination allows the light to be blocked when both are applied. But the light that isn't totally blocked is already polarized by the first built-in always-on filter. So you never get unpolarized (i.e. randomly or uniformly polarized) light out of it. And this will interact with glasses adversely. Airliner/private jet windows can also have non-uniform polarization effects which look clear with the naked eye but splotchy when viewed through polarized glasses.

I don't know about jet fighter canopies. Presumably they are coated because radar reflections off the cabin are bad news but that's a different wavelength. But they don't have any special displays that are non-polarized that I know of.

I think "polarized" specifies the direction of light they allow through.

I also think the splotchiness you see with some windows has to do with tempered glass--the varying stress in tempered glass shows when viewed through polarized glass.  In engineering, the effect is named after some dude I can't remember.  I think the effect is less in acrylic, but still can be noticeable.

[Caldera]

Hey All,

Do any of you guys fly the AV-8B? 

For me, that module is the the worst of the bunch I have tried.  It is like looking through dirty eye glasses all the time for me.  I quit playing with the module for that very reason.  I guess I have buyers regret to some extent.  Hence I have "Whine, on" in my pre-start check list.

I have not had a decent pair of "anti-reflection" glasses in quite a while.  But I fish allot, and when I used them, I do know that a major part of the glare goes away and I can see fish (in up to 30 feet) that I would not otherwise be able to even notice (if the water is clear).  The horizon line just jumps out piercing right through the haze.  I do not remember seeing that much gunk on my truck windows ever (referring to the AV-8B).  And..  I am not Mister Clean.

A quick search regarding LCD screens:  "Thankfully, there’s an easy fix: Turn the screen 90 degrees in either direction. This will align the polarizing filter on your screen with the one on your sunglasses, and the light from your screen will be able to pass through to your eyes." 

 

Saying all that that, I have zero experience with bubble canopies and I am not a private pilot.

Simulating a lousy ground crew?  I am not trying to rack on the Marines, but the simulated Air Force ground crews for the A-10C-2 deserve a meritorious award by comparison.

Caldera

Edited March 4, 2022 by Caldera

[jaylw314]

3 hours ago, Caldera said:

Hey All,

Do any of you guys fly the AV-8B? 

For me, that module is the the worst of the bunch I have tried.  It is like looking through dirty eye glasses all the time for me.  I quit playing with the module for that very reason.  I guess I have buyers regret to some extent.  Hence I have "Whine, on" in my pre-start check list.

I have not had a decent pair of "anti-reflection" glasses in quite a while.  But I fish allot, and when I used them, I do know that a major part of the glare goes away and I can see fish (in up to 30 feet) that I would not otherwise be able to even notice (if the water is clear).  The horizon line just jumps out piercing right through the haze.  I do not remember seeing that much gunk on my truck windows ever (referring to the AV-8B).  And..  I am not Mister Clean.

A quick search regarding LCD screens:  "Thankfully, there’s an easy fix: Turn the screen 90 degrees in either direction. This will align the polarizing filter on your screen with the one on your sunglasses, and the light from your screen will be able to pass through to your eyes." 

 

Saying all that that, I have zero experience with bubble canopies and I am not a private pilot.

Simulating a lousy ground crew?  I am not trying to rack on the Marines, but the simulated Air Force ground crews for the A-10C-2 deserve a meritorious award by comparison.

Caldera

 

A lot of civilian avionics screens are vertically polarized (I think) for that very reason, but the problem is that even a civilian GA cockpit is a pretty dynamic environment.  Every time you reach for a control or switch, or try to pick up traffic out to the sides, you're moving your head around.  I found out I couldn't use my polarized Ray-Ban's because every time I reached for the radio, my head would tilt a bit and the GPS screen would suddenly go dark.  Thankfully, I only had one GPS screen, but I can imagine it'd be pretty distracting to have all the various screens in the cockpit throbbing on and off every time you moved your head, and I have to imagine a fighter cockpit would be even much more dynamic.

[Caldera]

Thanks Jay!

Realizing the whole original topic is a mute point...

I do remember walking into my control room, with on the order of 20 or so LCD computer screens scattered around the room.  I was wearing a pair of $8 Wal-Mart specials.  These were really cheap fishing sunglasses and the cheapest that I could find, but they worked pretty good.  Some of the screens were indeed blacked out and some were just fine.  By turning my head 90 degrees I could get the opposite effect across the room glancing at the screens.  With my small capacity cranial cavity, for some reason I found that doing this over and over was some what entertaining.

I believe that those sunglasses were strictly polarized in a single direction, because the effect was so dramatic.  Much like having a single rotatable polarizing lens on an older SLR camera that you could find the direction for the best filtration effect by rotating the lens.  Or like wise, rotating it to remove the filtration effect.

I have heard that Ray-Bans (or some such better quality lenses) have polarizing filters in multiple directions.  That is why they work quite a bit better in most conditions (over just the cheapos) and typically are really amazing.  They also seem to need to be not as dark.  As I think that it is the polarizing filter(s) effect that blocks the light, not just strictly the darkness of the lens.  Other than that I have no clue.

FWIW, I hardly got bothered if I accidentally dropped the cheapos over the side vs a pair of high dollar Ray-Bans.  But a story for another day...

Caldera

Edited March 5, 2022 by Caldera

[jaylw314]

11 hours ago, Caldera said:

Thanks Jay!

Realizing the whole original topic is a mute point...

I do remember walking into my control room, with on the order of 20 or so LCD computer screens scattered around the room.  I was wearing a pair of $8 Wal-Mart specials.  These were really cheap fishing sunglasses and the cheapest that I could find, but they worked pretty good.  Some of the screens were indeed blacked out and some were just fine.  By turning my head 90 degrees I could get the opposite effect across the room glancing at the screens.  With my small capacity cranial cavity, for some reason I found that doing this over and over was some what entertaining.

I believe that those sunglasses were strictly polarized in a single direction, because the effect was so dramatic.  Much like having a single rotatable polarizing lens on an older SLR camera that you could find the direction for the best filtration effect by rotating the lens.  Or like wise, rotating it to remove the filtration effect.

I have heard that Ray-Bans (or some such better quality lenses) have polarizing filters in multiple directions.  That is why they work quite a bit better in most conditions (over just the cheapos) and typically are really amazing.  They also seem to need to be not as dark.  As I think that it is the polarizing filter(s) effect that blocks the light, not just strictly the darkness of the lens.  Other than that I have no clue.

FWIW, I hardly got bothered if I accidentally dropped the cheapos over the side vs a pair of high dollar Ray-Bans.  But a story for another day...

Caldera

 

LOL 

Polarized sunglasses aren't terribly expensive, although nowadays most cheapo sunglasses are plastic.  I don't know that multiple polarizing filters make things better, because the LCD still gets completely blocked at multiple angles.