Designing a Simple Periscope

I posted a link before on periscope designs. Here is another. I doubt that anyone here will do your work for you without compensation. We will help those who show effort. For instance, I believe that you are using the term "Camera Obscura" wrong. A camera obscura projects an image onto a flat surface using the pin hole effect to focus the image. This has nothing to do with moisture in the air or condensing on any surfaces. I'm certain the rainy season will effect optics but your choice of terms seems wrong.

Thanks a lot for correcting me.

1. Use as large a pair of mirrors as you can buy. First-surface mirrors will give a sharper image than common mirrors which are second-surface mirrors.

2. Seal the tube to protect the mirrors. Seal both ends of the tube with clear glass windows that can be cleaned and replaced if needed. It would be a good idea to have a door, or port, to keep some fresh dessicant in the tube, to minimize internal moisture.

3. Extend the tube beyond the windows. This will minimize moisture and dust from coating the glass and impairing the view. The rule of thumb is to extend the tube 1.5X the width of the opening.

4. Fogging is not the same as Camera Obscura. A Camera Obscura is a device, somewhat like an overhead projector, that uses a lens to create an image of an outside scene in a darkened room.

5. Be aware that you will still be looking through a 10-foot long tube. The image you see will be just a small region of your surroundings. If you want a panoramic view you would need a very expensive lens system.

Dear Usbport

I want to ask you that if I send you my design, would you help in modifying the same.

Thanks a lot

Send it to me and I'll look at it. I don't make promises to help unless I'm sure I can.

He told you what to do....are you completely helpless?....Why not find some local support...surely there is someone in your area who is willing to offer advise....

Mr. Solar Eagle

I hope this forum is made both for engineers and those who are not. Well I belong to the next group who want to materialize my idea with the help of cooperative minded engineers.

I found him to be helpful. If helping others is not the mandate of this forum, then I wont look for it.

Thanks

My suggestions were made to help you.....that was the purpose....Someone there could be hands on help, we, generally speaking, cannot....

In the past, I have received immense help from this forum. This has helped me to show the effect of Global Warming through mechanical animation. I strongly believe that if work could be done by the amalgamation of idea and expertise from different areas, a concept could be put up nicely.

Mr. Solar I have high views about this forum.

Well I am planning this exhibit for the kids to enjoy. I wanted the help for two reasons-

I am worried about the stability of 10ft tube made of square pipe and GI sheet. This structure would be mounted on a 4' pole and can be rotated by 360.

Secondly I am planning to install a parabolic dish on the top of it to catch sound which could be heard by the visitor while he is observing the periscope.

With this purpose I have already made a design. I wanted to send the same to you all so that you can correct it.If local support is available, why should I send it?

I hope now you understand why I reacted in that manner to your comments. As an engineer you will understand that any creation, however small, is very special to the creator. And if someone mocks it, it hurts.

Thanks again.

Any interactive display for public use should be subject to local permitting and certification....A local inspector should certify the plans for this and any other devices you plan to make available to the public....the proper materials and construction methods should be qualified by local authorities.....If there is no local authority, you should seek out the nearest available authority and have them ok the design and construction....this can not be done online.....You are asking someone else to be responsible for your actions without them having direct feedback and control over the situation....it's an untenable situation...

I agree completely. A ten foot tall, metal construction with a funnel like sail on top should require local authority approval. Particularly when this is intended for public use by children. There should also be a scheduled (annual?) maintenance plan to respond to the abuse mother nature and creative play incurs on this sculpture.

Now you can't see because some other #@$@&!! periscope is in the way of your periscope.

Oh gawd. Not another arms race, this time with periscopes. Periscopes on Parade in Red Square. Intercontinental Ballistic Periscopes. MIRPs launched from boomers. Periscope Wars/Strategic Periscope Initiative. Orbital periscope excimer lasers. Rail periscopes. The works. Can already hear those primates in Washington thumping their chests.

Wait til Tom Clancy hears of this. Periscope Dawn. The Hunt for Red Periscope.

No, John Cleese.

A suggested modification to the shape of the window tube extension: cut it at an angle so that birds cannot nest in it. Long at the top, short at the bottom.

It depends on several factors. If your tube is fairly well sealed, you can use desiccant to dry the internal gas. Desiccant, however will eventually saturate and need to be baked out or replaced. You can arrange to flow dry air through the internal optics to lower the dew point of the internal gas. Yet another option is to heat the optical components to above he dew point of the internal gas. An advantage of this third option is that it will eliminate condensation on both internal and external optics,

Who pays the heating bill?

I love it when people answer questions with new questions. Heating the optics can be achieved by coating with a thin layer of tin oxide that serves as an efficient resistance heater.

I like that you like question chains.

Adding tin oxide to anything may change the absorption or reflection coefficients but it does not add calories (heat) to a ten foot long pipe.

Adding heat to the 10 foot long pipe is not the issue. All we should be concerned about is maintaining the temperature of the optics above the dew point of the internal gas. This can be done by coating the optics with a transparent layer of tin oxide and connecting to a low power source., All that is required is to maintain the temperature of the optical components above the dew point of the ambient environment,