We had one other problem with our current arrangement and that was the fact that, as the image was reflected, it was mirrored horizontally. We realised the solution to this was to reflect the image first before having it hit the glasses and this also ended up solving the first issue. The only final problem was that of the person’s vision being affected by the use of the lens however that was easily remedied by the addition of a further lens from a set of equally strong (+3.50) reading glasses. The rough sketch of the final set up can be seen bellow.
We are still experimenting with the design and for now have not included the sunglasses in our prototype for the sake of simplicity; however it is something we are looking at implementing in the future. This is both for the fact that less light will reach the eyes making the screen relatively brighter and also that it looks far better and serves to hide all the electronics.
The reading lenses are from cheap sets you can buy in many local stores and the others are from an online prescription service that allows you to order glasses cheaply to a specific strength. This process can seem complicated but below is an image of how it should look when completed and is in fact very easy. The only number that needs to be modified is the SPH or spherical number, and this needs to be -3.50. The others should be 0 and the PD (pupil distance) is irrelevant and can be any number you like.
When buying/ordering the glasses buy the cheapest frames you can as they will not be needed at all for the project and can be thrown away as soon as the lenses are removed. To modify this setup for anyone who does require glasses already is very easy, all that needs to be done is to change the strength of the reading glasses so the difference in strength between the two matches you’re prescription and this can be done separately for each eye. For example I have -1.50 eyesight and so I would get +2.00 reading glasses to compensate (-3.50+2.00=-1.50).
The final consideration with the lenses is to try to find ones that match each other closely in size to avoid as much visual distortion as possible.