Part of the definition of a virtual image is that it cannot be formed on a screen. I understand this is the case when the screen is right next to the image, since there are no physical rays that can hit the screen. But what I don't understand is why an image can't form on the screen if the screen is located sufficiently far away from the image and/or lens so that rays do physically hit the screen? The 'explanation' usually given is that real rays converge while virtual rays don't, but how is the screen supposed to know if the rays it's seeing actually converged at some point or not? The only apparent difference compared to real rays I can see is that rays for virtual images would have greater angular divergence, which would create an image on the screen, just blurry.
[Physics] Why can’t virtual images form on a screen
optics
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A real image can be viewed on a screen, a virtual image can not. Rays from both types can enter your eye, be refracted by your eye's lens and form a real image on your retina as @CarlWitthoft points out.
So it is not the case that a real image must be viewed on a screen. It can be viewed on a screen.
which as far as I know is formed when the light diverges?
The lens tries its best and makes the light less divergent but is not powerful enough to make it convergent.
What you are asking for is a virtual intermediate image to the left of the first lens light from which is focussed a second lens.
Here is a possible arrangement of lenses where the first lens produces a virtual image and the final image is at infinity.
This is the ray diagram for a Galilean telescope which is much shorter than a conventional refracting telescope where the intermediate image is never formed and is said to be a virtual object for the second lens..
Best Answer
There seems to be some fundamental confusion here. An image is formed on a screen when light rays emanating from an object converge there. If there is no convergence of rays, then there is no image on a screen.
Think about a portrait located positioned on the left side of the lens. The light emanating from a point on the tip of the nose focuses to the (single) corresponding point on the image. The same is true of all the neighboring points, so there is a one-to-one correspondence between points on the image and points on the object, and the image is clear.
On the other hand, if you position a screen at a different location, then the light emanating from the tip of the portrait's nose will be spread over a whole region of the screen. The light from the neighboring points on the object will overlap, and the result will be a blurred image.
The conclusion is that the calculated image distance is where you will get a clear image; if you put your screen anywhere else, then an image will not form. Now consider what you'd get with a diverging lens.
The blue dotted lines are obtained by tracing the rays on the right hand side backward and pretending the lens wasn't there. The virtual image is the location from which the rays appear to be emanating from the perspective of somebody on the right-hand side of the lens. However, there are no actual light rays which converge there. If you place a screen at the location of the virtual image, can you see why you don't get a nice picture?