A technical challenge

[Hogster 0]

Hi all!

 

I have a technical challenge and I would appreciate your advice.

 

I work for an Aerospace company and I need to use a small video camera to relay the view from a pilot's eyepiece to a VGA / composite monitor.

 

Head-up display information is projected into the eyepiece via a tiny mirror, about 2mm square in the centre of an otherwise-clear eyepiece. Currently I'm using a pinhole bullet camera which looks directly into this mirror and all the information being projected is visible ... however, the quality is not sufficient for the purpose, even though it's a "600 TV Lines" resolution camera.

 

To see the camera, type '180EXPI' into Google and it's the second link, from Henrys.

 

We tried two other larger cameras but neither could capture all the information being projected by the eyepiece - only a circular patch of the information was visible, with the corners being cut off.

 

I'm not certain of the technical term of what I'm after, but what sort of lens should I be looking for if I want to capture information being projected at very close-range from a very small mirror?

 

Thanks for any help you can provide!

 

Kind regards,

 

 

David

[Guest]

Hi all!

 

I have a technical challenge and I would appreciate your advice.

 

I work for an Aerospace company and I need to use a small video camera to relay the view from a pilot's eyepiece to a VGA / composite monitor.

 

Head-up display information is projected into the eyepiece via a tiny mirror, about 2mm square in the centre of an otherwise-clear eyepiece. Currently I'm using a pinhole bullet camera which looks directly into this mirror and all the information being projected is visible ... however, the quality is not sufficient for the purpose, even though it's a "600 TV Lines" resolution camera.

 

To see the camera, type '180EXPI' into Google and it's the second link, from Henrys.

 

We tried two other larger cameras but neither could capture all the information being projected by the eyepiece - only a circular patch of the information was visible, with the corners being cut off.

 

I'm not certain of the technical term of what I'm after, but what sort of lens should I be looking for if I want to capture information being projected at very close-range from a very small mirror?

 

Thanks for any help you can provide!

 

Kind regards,

 

 

David

 

It sounds like you have a lens mis-match with the larger cameras.

 

The lens should be equal to or larger than the sensor size. (ie 1/3" CCD camera should be fitted with a 1/3" or 1/2" lens, but 1/2" CCD camera should not be fitted with a 1/3" lens).

 

I would consider looking at a macro lens which gives you the ability of very short range focusing. If higher resolution is required, consider at looking at cameras from the machine vision market and not the CCTV sector.

 

Hope this helps

 

Regards

 

Ilkie

[Hogster 0]

Thanks for your reply Illkie!

 

I think it's more a case that with the larger cameras we can't get the lens significantly close enough to capture the whole of the projected information. Think of it as looking through a keyhole and trying to see an entire room ... We're going to try this camera next:

 

http://www.rfconcepts.co.uk/21cph-spec.pdf

 

... which has the same FOV as the bullet camera and should be able to get right up close to the mirror in the eyepiece. Also the image quality should be better as the lens is much more substantial than that of the pinhole camera.

 

The larger camera we tried before had a zoom lens which retracted into the body of the camera when you zoomed in, moving the lens itself too far from the mirror to capture all the information.

 

I will let you know how we get on

 

Sorry for the long delay in my reply!

 

All the best

 

David

[zmxtech 0]

yep I think ILK has it try some different lenses

You also get shrouding when something is blocking the lens [holes not big enough?]

 

z