A possible solution is a Kerr cell shutter used in 3D glasses.
View attachment 270615
The glasses would be synchronized with the projected image. The projected image would alternate between the desired image and some other random image that tries to mask out the desired image.

thank you mr chips for your answer, this technology I do not know, how this technology can help me by alternating images, I did not understand well

 

An array of slats in front of a back projection screen could limit the view to a narrow angle. That is similar to how how the flipping image cards work.

yes yes bob I thought it too, in fact this projection is already limited to angle variations, if we then increase the accuracy it becomes very difficult, however I remain with the idea of using the classic directional projectors such as those used in guardini on the ground, which cast a beam of light

 

Now it seems that the goal is for multiple people to be able to view the image, all at the same time, but with the projection being into their eyes directly. That is not possible with current technology, nor without a great deal of additional complexity. Also, probably never happening. So either project the images onto a screen for all to see, or provide all with individual VR headsets similar to what game player use.

no no mr blitz only one person must see the images, and no more people, in the sense that by projecting on that person he must see it without the person wearing any tools (glasses, contact lenses). not because there is secrecy in the content of the projections, but to have a greater reality, I think cue bob has understood what I want to do

 

Actually, where did you get that idea? The goal is to project an image on a screen some distance from multiple people such that only ONE can view it.

As stated in the original posts.

yes in fact a person must see only the projection this is the only problem, it is a projection like all the others only that only one person must see it and not all of them, obviously the person must not have glasses or contact lenses, but only the naked eye, as in all projections

 

In that case it is simple. Project the image using infrared, or maybe ultraviolet, and only one person has the glasses to see it.
But really, with so many descriptions it does get mixed up.

no as there is the damn sars-covid virus I cannot put glasses or contact lenses or other tools on people who need to see the projection, but use a projection with the naked eye like all projections, for example at the cinema or when they are seen I show them at school

 

The TS responded to the contact lens solution…


So I think that putting VR or 3D glasses on everyone won’t cut it.




However @MisterBill2, I like your idea. Projection in the IR or UV band may be the ticket!

no as there is the damn sars-covid virus I cannot put glasses or contact lenses or other tools on people who need to see the projection, but use a projection with the naked eye like all projections, for example at the cinema or when they are seen I show them at school

 

thank you mr chips for your answer, this technology I do not know, how this technology can help me by alternating images, I did not understand well

A Kerr cell is a very fast voltage controlled shutter. Like window blinds or a camera shutter, it can block light from passing through the lens. This is used in 3D theatres to alternate between images to the left eye and the right eye.

For your application, you would allow the normal image to be visible for a percentage of the time. When the shutter is closed a random image will be projected on to the screen in order to confuse the user not wearing the special glasses. That's the theory. How well this will work is up to question.

 

How are the person who sees it and those who do not situated? And where is the screen in relation to them. And why don’t you just tell us how this going to be used? Is it some kind of game? A classroom educational method? A carnival thrill ride?

In a heads up display in a car, the driver sees it but not the passenger. In that situation the difference in angle is pretty large. Is that true here?

At least some of us get it now that the viewer cannot have any special equipment, and that any viewer will see the image when in the correct position,

 

No matter if this idea is destined to cheat of some kind, magic trick in Tasmania Got Talent or God knows what else, the explanation is slowly coming out but reluctantly. My feeling that a statue-like reader is needed is still in my mind. Just a strong push side wards and bye with reader and the trick.

 

How are the person who sees it and those who do not situated? And where is the screen in relation to them. And why don’t you just tell us how this going to be used? Is it some kind of game? A classroom educational method? A carnival thrill ride?

In a heads up display in a car, the driver sees it but not the passenger. In that situation the difference in angle is pretty large. Is that true here?

At least some of us get it now that the viewer cannot have any special equipment, and that any viewer will see the image when in the correct position,

well bob your questions are legitimate because it is normal that you want to know. So as already said it is for a playful and educational purpose, in this way I can get my kids involved more emotionally in small films that are innocent, and also to bring them closer to technology, you will remember that in my old posts I help boys in difficulties, together with other volunteers like me. so I think you have understood the task, unfortunately the guys don't have to wear any tools because of the covid, I really like your idea of the display projected on the windshield of the cars and I think that is the solution, the important thing is that, the projection it is visible only to a certain person facing the front and that the image is seen as if it were real in low distance, but I think that for this I need a good lens, ok so I think I have almost reached the end, tell me now what should i buy and how can i assemble please

 

No matter if this idea is destined to cheat of some kind, magic trick in Tasmania Got Talent or God knows what else, the explanation is slowly coming out but reluctantly. My feeling that a statue-like reader is needed is still in my mind. Just a strong push side wards and bye with reader and the trick.

yes yes obviously my idea looks funny to my kids but no gambling or other dangerous stuff, unfortunately I didn't understand (due to the translation), what you meant in the second half of your answer about a reader and a statue

 

A Kerr cell is a very fast voltage controlled shutter. Like window blinds or a camera shutter, it can block light from passing through the lens. This is used in 3D theatres to alternate between images to the left eye and the right eye.

For your application, you would allow the normal image to be visible for a percentage of the time. When the shutter is closed a random image will be projected on to the screen in order to confuse the user not wearing the special glasses. That's the theory. How well this will work is up to question.

hi mrchips I have read your answer and I believe that Kerr technology can be applied even without the use of glasses, also because, as he has already said many times, spectators do not have to wear any instrument, but I can alternate the image, and even between the two eyes, only unfortunately, I'm not understanding what it can do for me, I think it can help me, but I can't understand how, I think it can help me by creating a 3d holographic effect, right? or am I wrong?

 

I will assume that you want to do this for the purpose of entertainment. For example, you are a performing magician and want to perform some mind reading tricks.

If you are the only viewer standing directly in front of the image, I would like to suggest an LCD computer screen with a Fresnel sheet placed over the screen. The image is only visible to a person standing directly in from of the screen. Persons standing to the side of the screen cannot see the image.
The image on the LCD may need some modifications for this to work, i.e. the image is masked with vertical stripes.

 

yes yes obviously my idea looks funny to my kids but no gambling or other dangerous stuff, unfortunately I didn't understand (due to the translation), what you meant in the second half of your answer about a reader and a statue

What is your native language?

 

What is your native language?

Troll?

 

I will assume that you want to do this for the purpose of entertainment. For example, you are a performing magician and want to perform some mind reading tricks.

If you are the only viewer standing directly in front of the image, I would like to suggest an LCD computer screen with a Fresnel sheet placed over the screen. The image is only visible to a person standing directly in from of the screen. Persons standing to the side of the screen cannot see the image.
The image on the LCD may need some modifications for this to work, i.e. the image is masked with vertical stripes.

perfect I will implement this technology in my projector, but now I want to know how I can narrow the light beam so that when the image reaches the eye it can occupy the whole visual head, today I did an experiment with my binoculars and it worked, I placed a white LED in front of the binoculars and the beam that came out s narrow and also the narrow beam, when I pointed it in the eyes (yes maybe a bit stupid), I only saw the beam of light and not what surrounded me wow, now, how can I implement all this with suitable lenses?

 

What is your native language?

I'm italian

 

Troll?

no I'm not a troll, please don't make fun of me, it's very difficult for me to communicate with you with a translator and answer each of you, it's not a joke, we are almost at the end I just miss the optics part, es an experiment that I did at home and I described in the previous post, gives me hope

 

this is what i want

 

in my little experiment at home, as you can see from the image I turned on the flashlight of my smartphone and brought it close to the mouth of my binoculars and thus a narrow beam of light is projected (that circle in the third floor)