Undergrad Collimating an extended source to infinity?

[nikosb]

I need to collimate an extended source (for example a cell phone) to infinity or as far as possible. I show an illustration below

The collimator lens is about 2cm from the eye and the extended source is about 60cm from the eye. My understanding is that a collimator lens with a focal length of 60cm (58cm in this case) would do the job. I have some double convex lenses with focal length of 50cm and 100cm. I experimented with them by placing the extended source at the corresponding focal length and then looking though the lenses with one eye and the other eye closed. In general the virtual image appears a little larger but also a little blurry. However I did not get the sensation that the virtual image was located at infinity or anywhere close to infinity. I felt that the virtual image was only slightly farther out proportional to the amount of magnification. For example, if the image was magnified by 1.3 times (it appeared about 1.3 times larger when looking through the lens compared to when looking without the lens) the location of the virtual image was 1.3 times father out. This seems to be consistent with the mathematic of the lens equations (https://www.physicsclassroom.com/class/refrn/Lesson-5/The-Mathematics-of-Lenses):
M = hi/ho = di/do

Can I collimate an extended source as shown above and if yes will the collimated image be at infinity? If the above setup is correct then why do me eye doesn't get the sensation that the virtual image is located at infinity?

 

[berkeman]

How is a 3cm x 5cm phone LCD display an extended source?

 

[nikosb]

I thought in optics there are two sources, a point source and an extended source. A point source is single point while an extended source is a collection of points. The phone being larger than a single point (a collection of pixels that emit light, each pixel being a point source itself) would be an extended source, correct?

 

[A.T.]

I need to collimate an extended source (for example a cell phone) to infinity or as far as possible. I show an illustration below

View attachment 237616

https://en.wikipedia.org/wiki/Head-up_display#Overview

 

[sophiecentaur]

That makes sense and it's how 'reading' spectacles are designed. The problem is with the distance between the eye's lens and the correcting lens because the two together constitute a compound lens. I am basically myopic and the images I see in my specs is reduced in size (they are concave lenses of course) so it's not surprising that a convex lens will tend to magnify the image. You could try placing your lens as close as possible to the eye of the observer and see how much the magnification is reduced. OR . . . . use a smaller image in the cell phone screen, zoomable to suit the observer, perhaps.

 

[Andy Resnick]

I need to collimate an extended source (for example a cell phone) to infinity or as far as possible. <snip>

Can I collimate an extended source as shown above and if yes will the collimated image be at infinity? If the above setup is correct then why do me eye doesn't get the sensation that the virtual image is located at infinity?

I don't understand what you are trying to do. If your source is extended, placing it the rear focal plane of a lens will not generate a single plane wave, which is usually what 'collimated' means. As for why it 'looks' the way it does, don't forget your eye is also an optical system- not just a retinal sensor.