Is it possible to make glasses that make everything brighter, but do not magnify or focus?

First, let me try to clarify the question, because not everyone seems to get it ("where would the photons come from?"). If I'm buying binoculars, I might choose from 8x24, 8x36, or 8x50 binoculars. The first number is the magnification; 8x for all the examples. The second number is the size of the objective in millimeters, 24 to 50 millimeters in the example. All else being equal, the larger objectives will gather more light, and produce a brighter image. The 8x24 and 8x50 binoculars will deliver the same 8x magnification, but the 8x50 pair will be brighter.

So it's reasonable to ask if you could make 1x binoculars that have a big objective that brightens the scene in front of you. There's no conservation of energy issue here; the larger front objective would gather more light. The problem is that there's a relationship between the magnification and the sizes of the entrance and exit pupils:

magnification = entrance_pupil_size / exit_pupil_size

If you create a binocular with an entrance pupil (objective, basically) that's larger than your eye's pupil, so that it can gather more light than your eye's pupil, then at 1x magnification, the exit pupil is going to be just as big as the objective lens. And since that's bigger than your eye's pupil, the "extra" light is going to run into your iris instead of going through the pupil, and you will gain no advantage from it.


Expanding a bit on what ptomato said, I think there's a problem with the second law of thermodynamics regardless of any problems with the first law.

Suppose the universe consisted of two things: a black body the shape of eyeballs and the microwave background. Then the black body would come into thermal equilibrium with the microwave background.

Now we introduce these glasses that make things brighter, placing them in front of the black body. Suddenly the black body has more light coming on to it. It absorbs all this light, so it has to heat up. We made heat flow from a colder place (the microwave background) to a hotter place (the black body) by a passive optical phenomenon. That violates the second law.

EDIT: It turns out this principle is called "conservation of brightness" or "conservation of surface brightness" and is well-known in optics. See, for example, http://www.cv.nrao.edu/course/astr534/Brightness.html


You want an optical amplifier. It uses stimulated emission to amplify the light, like in laser, but without the feedback loop. Generally used for amplifying fiber optics signal to greater than 200 km. Making wearable glasses with this wouldn't be easy. Inverting electron population of a piece of glass with enough gain to be useful. As ptomato noted it is an active device, therefore in needs a power source to feed it. But I don't think your are concerned about this.