English language

How to pronounce visual display unit in English?

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hello and welcome in today's video today I will be discussing about what is a polarized lens so
polarized lens is something which we have heard about a lot so today we will be looking at what
is a polarized lens what is the principle behind a polarized lens what is the application and
how they are produced and delivered to us so let's start the video and go through what is
a polarized lens so before we start with what is a polarized lens we should know what is polarization
of light so when we see the term polarization that basically means changing its state from one
to another so we all know that a light source which is generally emitted is vibrating in all
directions so basically so you have a horizontal as well as a vertical two components which are
there so what happens when light is vibrating in all direction it is called as an unpolarized light
so what does polarization means unpolarized light is when a light is not having one single direction
rather having multiple directions of vibration so when you use a polarizing filter or rather
any material which can obstruct all the other vibration except leaving one to go undeviated so
that is what is called as a polarized light so a polarized light will have only one direction
of vibration which could be either horizontal vertical or oblique depending on the axis of
your polarizing filter so what is the application of a polarization lens or a Polaroid lens what
happens that whenever we go outdoors the array of light which comes from any flat surface the
emitted light from Sun or anything when it hits a reflecting surface so a flat surface will create
a reflection from it and the unpolarized light will start getting changed into a horizontal as
well as a vertically polarized light which is partially polarized so the horizontal polarized
light will act as a disturbance or a glare for you whereas the vertical light is the one which
is required to see clearly so what happens that when we introduce a particular polarizing filter
and depending on to the it will cut off one particular Ray and allow the other one to
go inside so let's take this example here so what is happening that when we are not using
a Polaroid lens particularly in a car the ray of light which is coming from Sun and getting
reflected from surface or a flat surface which could be either a water or even your road so it
changes it into your horizontally polarized light whereas that that light which is coming directly
is the one which is required for us so now I need to cancel out this horizontal with the help of a
polarized filter so the moment I introduce the polarizing filter which is cancelling of your
horizontally polarized light that will only allow me the light which is coming straight
or rather the direct light which is required to view clearly so what is happening the noise
or the glare which was introduced because of the partially polarized light coming from the
reflecting surface gets cancelled off and you get a better image or a better quality of image
so what is the application of polarized light or how it is done so here is the video which
explains us so because of the surface reflection which is coming either from your flat surface or
from water bodies are generally giving you a visual noise or glare and not allowing the
wearer to see completely clear the moment you introduce a polarizing filter in front of you
what happens it generally cuts off the Rays which are coming as horizontally polarized so if you see
in this demonstration here the lens is blocking the completely horizontally polarized light
which is getting reflected from the reflecting surface or a plain surface that has happened
because of the fact that there are some crystal present inside the lens which can cut off this
particular horizontally polarized light or rather the partially polarized light which is giving you
the glare so they obstruct this particular ray and gives you only the visible light which is required
to see things clearly and because of which what happens the surface reflection which were coming
or the polarized light which was coming off the surface gets cancelled off and you get a better
image or rather a clearer image less glare so how polarized lenses are made this is a very
important point because we need to understand how this Polaroid or rather the polarization happens
because of this lenses so what they generally do is a roll of PVA that is polyvinyl alcohol
is stretched six times so what they do is they heat this material or the sheet and completely
stretch it to become long sheets or elongated sheet and then they go through an iodine bath
so what happens then when it is heated and went through a iodine but this iodine crystals will
start getting accumulated onto the long sheets of your PVA in one particular axis of direction
then once they are having a iodine bath after that they are rolled in between two cellulose
acetate butyrate sheet so what happens there is a formation of a sandwich kind of lens in which
there is a two side there is your lenses which is present and in between them there is a polarizing
sheet with one particular axis now because the sheet has an axis of your horizontal it will
cut off all the horizontal and rather allow the vertical amount of light to go through it so what
are the available colors which can be seen into a Polaroid lenses commonly we see three types of
tints in it that is grey brown and green as of now there are the three tens which are commonly
seen in your Polaroid but also many other colors like in mercury or rather what we call as a mirror
coat they are also available even some colors like blue and other are also available in forms
of Polaroid coming on to the advantages what are the good points or what are the advantages of your
Polaroid or what is the use of it first of all it reduces the visual noise or glare which is very
much while driving because as we know from front of road or rather a flat surface lot of amount
of light is being reflected onto the driver's face or rather the person who is driving so this amount
of glare can be reduced with the help of your Polaroid lenses which gives you a better visual
performance and increases the efficiency as a driver the next point is for fishermen special
the one who are more nearer to the water bodies so what happens as we know water bodies are also
having quite a good amount of reflection of the Sun as it is also acting a flat surface where
amount of light reflected from the surface gives more of visual noise so the moment we introduce
a polarized filter what happens this visual noise gets canceled off or the glare is reduced and the
fishermen all the people working near the water bodies can see the image or rather the object
below the water surface more clearly the third is it is having good amount of UV protection so
it is good for the eyes as it protects the eyes from UV as we know the UV light is quite harmful
in terms or rather giving more abnormalities it increases your maturation of the lenses so because
of which it could lead to early cataract or rather some other damages so it is good that you have a
UV protection finally in sports like skiing and others what happens because ice is again acting
as a quite flat reflect reflective surface the skiers might have a good amount of reflection and
that can give you a blinding effect so Polaroid helped to avoid that and give them a better and
enhanced vision coming on to the disadvantages the biggest disadvantage of them is that because of
the fact that Polaroid lenses start showing you the colour fringes or the stress pattern in any
plastic or anything whichever has a stress pattern so generally what happens in carbon shield which
are made up of toughened lenses so in toughened lenses there are stress pattern which are present
and this press stress pattern are seen as colour fringes whenever you wear a Polaroid so if you
wear a Polaroid and see any particular safety glass or other event shield which is toughened
that will show you stress pattern in form of colour fringes then next is your visual display
units so it is quite a problematic for people who work in front of your visual display unit
at the same time using a Polaroid so generally these are pilots and drivers so if they have
any visual display unit at which they want to see they will see colour fringes because of the
clear transparent screen which is present over the display unit which again has a toughened
nature and giving you a stress baton the next is having glares and watching through your aeroplane
windshields or other the windows of your aeroplane which are again you having your polycarbonate or
rather the toughened lenses they also give you a colour fringes finally in skiers what happens
as we know the polaroid lenses are into one particular axis so as you change the head position
or you change the direction or axis of the Polaroid the effect of Polaroid starts changing
and that could give you again more disturbance so the common campaign which skiers give is that
whenever they are taking turn or they are tilting on one side the effect is reduced or the effect is
kept on changing which could give them confusion that exactly what is the Porsche perception of
that particular field know how to demonstrate a polarized lens so how do I understand if my
lenses are polarized or non polarized the simplest test which can be done is that when two lenses are
kept at same angle that that is your parallel to each other they will transmit the complete
amount of light but the moment they are rotated and kept perpendicular to one another such that
one is at 90 and the other one is at 180 that will give you complete blockage of light as
both the polarizing filter are stopping both your horizontal as well as the vertical rays
of light and no light is further allowed giving you a complete darken or a blacked-out state the
other way you can check that if it is a Polaroid or not that when you tilt at one particular angle
it will give you the complete transmission but at the opposite angle it will completely black out
and give no transmission to the lens the third way is simple that you wear a Polaroid lenses
and you can see your phone screen or any visual display unit and if it is showing a chromatic
fringes that mean is that the lenses which you are wearing is a photochromic lens thank you
for watching our video on polaroid lenses I hope it made you help understand what is a polarized
lens and what is the advantages disadvantages working in principle please like this video
and subscribe our channel we will be back with more videos on optometry thank you and goodbye