Adaptive Sunglasses

Synopsis

All current sunglasses and lenses are aimed to reduce luminous intensity of field of view as a whole, to enable an eye or a sensor to process the image better. In other words, we can see better when the image is not too bright. But what happens to the objects that are not that bright when we use sunglasses? When we are in the desert environment, and there are some objects that are using camouflage? Or when we are driving at night and there are bright objects shining right at our faces? For example when there is an oncoming vehicle, there are not many options that are available. Either we don’t look at it and look at the side of the road, not to get blinded, or we look straight and get blinded. The situation is even worse when the oncoming car has its high beams on. We can’t have sunglasses at night, since we wouldn’t see the road in front of us.

This idea provides the solution in form of Adaptive Sunglasses, which filter out only the bright object in the field of view, and not unnecessarily dimming the rest. They can be constructed using current technology, and can range from low quality builds from your own garage, all the way to the NASA grade, filtering even tiniest sources of light, leveling out the brightness of the field of view.

Following image is a rendering of the resulting effect. By looking through adaptive sunglasses, small circles could be seen covering the brightest areas. Those circles comprise the adaptive part – small pieces of polarized filter that are able to roll in place, changing the level of double polarization and dimming only the brightest objects. Notice how without the adaptive sunglasses, much of the field of view is invisible or poorly visible to the eye.

Adaptive Sunglasses

Since the adaptive sunglasses will always level out the whole field of view, the eyes will always see the most details that are visible. Light is not created, so the dark objects will remain dark. What adaptive sunglasses do is dim only the bright parts of the view.
 

Functional parts

The glasses will be based on two layers, the front and the back. The two layers are required to dynamically adjust double polarization factor based on trajectory of the light source to the retina, in order to be able to dim only the light source, not the surrounding imagery. Back layer will be close to the eye retina, in the same manner the normal sunglasses are today. The front layer will be only a millimeters away. Very good designs can have front layer only micrometers away, if it is deemed necessary.

The back layer will contain a static linear polarization filter. Exactly at the point where the eye retina will be the closest to the back layer, there will be a sensor array. This sensor array will consist of a group of triangular sensors, aligned into a hemisphere shape in a geosphere fashion (To get the picture, you can imagine half of the golf ball, where each little surface is the sensor). For accuracy purposes, each sensor will be surrounded by a thin wall. This thin wall will effectively filter out any indirect light, so the sensor will react only to a direct light (Imagine looking through a tube with an eye – you will always see only the small part of your field of view). But there are many sensors, and in fact, there are just enough to cover the whole field of view (This is analogous to having enormous amounts of tubes for your eye, and your eye can view through all of them at the same time. So if the light coming from the tube is too bright, it will be dimmed). The whole sensor array will be, of course, very small. Therefore to the wearer, sensor array will be visible no better than a little dot on the standard sunglasses (meaning almost invisible). Each sensor of the sensor array will control one Adaptive Filtering Segment at the front layer, which will then dim or brighten the view for the eye, depending on the brightness perceived by the sensor.

The front layer will be composed of small linearly polarized objects – the Adaptive Filtering Segments (AFS). These can be in any shape achievable, but best designs will have a circular shape, since only this shape can achieve a 100% coverage (Note: To achieve complete coverage, two very closely located layers of AFS will be required, to account for gaps between the circular shapes. Then the adaptive sunglasses will have three layers in total, but the resulting effect will be of the highest quality). When AFS will be in line with the back layer, the light will be polarized only once, therefore no significant dimming will be incurred. But each AFS will be able to roll independently, changing the final double polarization factor from zero to 100%.
Double Polarization Effect
Double polarization factor of 0% results in 50% dimming, depending on the light source properties. On the other side, double polarization factor of 100% results in 100% dimming, meaning complete darkness. Therefore the adaptive sunglasses do not have the limit on the light source intensity, and will allow looking directly at the Sun, even in the desert environments. Sure, they are not going to protect the wearer from lasers or bullets, but being able to wear the same sunglasses at the darkest of nights and at the brightest of days enable total freedom of viewing pleasure.

Wiring will convey information from each sensor to the aligned AFS, which will then roll up to 90 degrees, therefore independently controlling double polarization factor for each area in the field of view. In effect, the eye will always perceive every part (the “part” being as big as the size of a single AFS, meaning the smaller they are the finer the view) to be of the same luminosity. This is, of course, unless the brightness of the object is lower than the certain degree – adaptive sunglasses do not create light, so if some object is dark it will remain dark, but actually the eye might see it much better, since human eyesight is also adaptive. For comparison purposes, imagine seeing the dark room after looking at the bright object (e.g. imagine turning off the lights in the room during dark evening and looking around immediately after that), and seeing that same room after the eyes had the time to adapt to the darkness. You will see more objects, and in fact you may see almost all objects in the room clearly (depending on the ambient light, of course). Therefore adaptive sunglasses will create perception that some object have become brighter. And this is what this idea is after – to make everything clearly visible.

Alternative designs of AFS, sensor array, and reaction principles are possible, with one of the designs presented as the basis for initial prototype construction.
 

Energy supply and consumption

Although the system may seem active, because the adaptive filtering segments have to constantly adapt to the environment, it is passive in nature. That is, only intensive luminance will provoke a reaction of sensor in the array, and that reaction will in effect turn the aligned AFS. This fact makes the need for battery power source redundant and allows using just the solar power cell. Solar power cells go hand in hand with adaptive sunglasses, because the AFS and sensor array need to be more active when the scenery is very bright, and when the scenery is very bright the solar power cells will provide more power. So the more active the adaptive sunglasses must be the more power will be provided to cover the electrical needs by the solar power cell.

To simplify initial design, solar power cells will actually be used as sensors in an array. This is also the most practical design, since no batteries and no complicated sensors are required. Alternative designs can include solar power cell in a form of a strip placed on part of the frame, providing power to the sensor array, or charging the rechargeable battery that will power the sensor array and the AFS rolls.
 

Principle and Architecture

Field of view (FOV) usually contains objects reflecting or emitting light at various levels of intensity. Due to limitations of the human sight, it is often necessary to reduce the radiant intensity. For example, if the sun is located in the FOV, human eye will be able to interpret much less information about surroundings due to high intensity of the sun. Reducing illuminance of the FOV as a whole can have considerable drawbacks. Using sun as an example, if the FOV illuminance is reduced so that human eye can clearly see the sun, almost all other objects in the FOV will not be visible due to considerably lower light emission/reflection.

Adaptive sunglasses even out FOV illuminance by dynamically adjusting the factor of double linear polarization. As mentioned before, glasses will not be able to amplify or illuminate any light sources (at first stage of the development) but will be able to reduce brightness of only certain objects based on the intensity of the emitted  light, and will not affect light sources of average brightness. Therefore FOV will be perfectly comprehensible to the eye not only in common environment but even in the harshest ones like deserts and space. Because maximum factor of double polarization will block 100% of the photons, there is no limit to the original illuminance intensity. And because of analog nature of the design, the granularity is only limited by the quality of design implementation.

Sensor array (SA) will be designed to correctly identify the exact angle to point of origin of the light source. Since the field of view is relevant to the observer, primary function of the sensor array is to identify the correct location of point of light source origin relative to the eye retina. Therefore SA must be located as close to the retina as possible, simultaneously covering usual retina location relative to the eye socket up to 95th percentile of population. Amount of individual sensors that compose SA is actually irrelevant as long as the correct angle to the point of light source origin to the retina is conveyed. Initially SA will be comprised of 24 hexagonal cells, each serving as a sensor. Each cell will control AFS in the field of view. Alternative designs can include only one sensor controlling all AFS, or thousands of sensors controlling thousands of AFS. Since the eye resolution is limited to about 6 megapixels, it is not necessary to create sensor array containing more than 6 million sensors. Because primary objective of SA is to correctly identify the exact angle to point of origin of the light source, physical design will play major role in information granularity. To correctly identify correct angle to the source, initial design will implement tunnel effect to separate field of view into areas. This tunnel effect will be created by placing a miniature wall around each sensor in the array.

Sensor can be no more than a solar power cell, producing more electricity depending on light source intensity. As the light source intensifies, power cell will produce more energy. The higher the energy, the higher the resulting AFS turn rate will be, therefore the larger double polarization factor will be achieved, and therefore the dimmer the source will appear relevant to its original luminous intensity. Movement of the AFS will be limited by 90 degrees, not to exceed 100% double polarization factor.

As the light sources dim in certain areas of FOV, AFS will gradually return to initial position, therefore controlling double polarization factor needed to transmit light at desired luminance. Without any energy, AFS will always tend to return to initial position, not unlike voltmeter. Conversely with higher intensities, double polarization factor will gradually increase. Preset limit of luminance will constitute when AFS will turn to the maximum double polarization position.

As a possible modification, all sensors in the sensor array could be covered by linear polarization layer just like the back layer. This will result in the sensor to perceive the same luminance as the human eye will see in the final result. All the limits will then have to be set and controlled based on the desired level of luminance, not at the actual luminance, because as the double polarization factor increases, less light will hit the power cell. Since the sensors will perceive as much luminance as human eye, and sensors control what human eye perceives, a logical loop is created. This loop will result in continuous adjustments of the system. For higher viewing comfort, sensor reaction times could be adjusted.

AFS design decisions could be made in the future based on user preferences. AFS with extremely fast response and fast adjust rate will be able to even out FOV illuminance very fast. Good implementations will result in such a high rate, that it will not be perceived by the eye. Cheaper designs will not be able to achieve this and will produce a flickering effect, similar to that of a fluorescent light sources, that could be unpleasant to the user. AFS with fast response and slow adjust rate will have smooth movements, but could create usability problems since system will have to be pointed at the FOV some time before evening out the illuminance. Advanced designs could incorporate logarithmic algorithms of AFS control to immediately react to more significant changes and react slower when the system is in the adjusting state.

As long as there will be light sources in the field of view, the system will be continuously adjusting itself in the described fashion.
 

Summary

Adaptive sunglasses will enable humans to get the most information out of the field of view. By dimming only the brightest objects, human eye can adapt to the lower brightness and perceive more information out of the dimmer objects. Glares, flares and other effect will be completely eliminated, and the field of view will be unnaturally even in brightness.

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