How do you focus X-Ray vision?

I expect it would be a lot like how we focus our normal vision. When I’m driving, I can choose whether to look at the windshield or through the windshield. Similarly, I imagine that Superman can decide to look at a particular level or through it.

If I were Superman here’s how I’d do it. I would accept that X-rays are not steered by magnetic or electrical fields I would also figure they will pass through my eye lens without being refracted. I would make my detection device, my eyes’ rods, cones, and spheres have phases array capability. I would slow down the response of certain areas of the retina so the desired signal was in phase and additive while the undesired signals were out of phases and cancelled out.

In the real world this is how one makes a flat low earth satellite tracking device with no need for special mounts or physical tracking. You just plop the rubberized panel on the ground and forget about it. Let’s assume the flat antenna is a 30 cm square (1 foot square) and it has 10000 small detectors spaced evenly across its surface. Also assume the antenna is being illuminated by many satellites on a similar frequency. The result is a jumble of noise (out of focus). As the desired satellite clears the horizon the signals reach the front edge of the detector 1 ns before they reach the back edge. Since you know the exact position and velocity of the satellite of interest you tune your detectors so the ones closed to the satellite are delayed so the wave front matches the time or arrival at the rear edge. This is easily done digitally or by using a form of programmable capacitance. As the satellite moves across the sky you recompute and modify so only the signal of interest arrives in phase. Look up phased arrays.
I would give Superman the ability to delay the signal out of his retinal spheres. A few picoseconds of modification and he would have a resolution of better than 1 mm.

Y’know, I asked my buddy Superman that same question once. He said it wasn’t any of my GD business!

He, no doubt, said that while looking at your business. ;-)

Excellent simple answer, @SavoirFaire.

Great technical (over my head) answer, @LuckyGuy.

Sorry, I meant the real Superman, @kritiper, not the airport-security perv in his Underoos.

The take away message is that it is possible to focus something even though a lens or magnetic field or electrical field can’t do it. Rather than trying to fight physics and move an unmovable object you modify the detector which is completely under your control.

Another advantage of this technique is that you can instantly move from one satellite to another without mechanically moving the device.
Superman can instantly look at the wall, the woman behind it and any other part he want to visualize in detail by adjusting his retinal array.

When he retires he can sign up at one of the cancer medical centers that charge $20,000 for a localized radiation treatment. He can charge half that and place the beam right where it needs to be – as long as he doesn’t get distracted by the patient’s other attributes. “Wow! Look at the size of his – oops! Nevermind.”

This is the subject of the 1963 horror film, X: The Man With the X-Ray Eyes.

Spoiler: note the rumoured alternative ending.

The answers above are great, but there is an additional problem. Where is the x-ray source? If Superman’s eyes are the detectors, he must have an x-ray source on the other side of whatever he wants to look at. Because in the movies, the images he sees are more like transmission images than backscatter images, which he would see if he was the source also.

@FireMadeFlesh Good point about the backscatter. Based up the sample images and the fact that Lois Lane continued to maintain her youthful appearance and vigor for decades I must conclude Superman was not the source.
He must be using the naturally occurring background radiation from distant cosmic events to visualize his area of interest. When I look out my double glazed kitchen window I see grass and trees laden with apples all bathed in radiation that originated in the sun, 93 million miles away. If a mere mortal like me has a pair of detectors with that sensitivity and resolution, just imagine the capability of the devices equipped by the Man of Steel.

@LuckyGuy You’re right, background radiation has to be the answer. If that is the case, I estimate that the receptors in his eyes must be around 3 million times more sensitive than our best x-ray detectors. That’s pretty impressive sensitivity from a guy who can stop bullets with his skin!

He’s packing quite a dynamic range. We know he’s at least 3 million times stronger than all of humanity. Remember, he once reversed the spin of the Earth to save Lois. Meanwhile several million unnamed Bangladeshis had to suffer the pain of drowning twice in a flood resulting from a regional typhoon.
But he did save Lois so it wasn’t all a waste.

@FireMadeFlesh It’s not literally X-ray vision. That’s just the name given to his power because it was the closest related concept at the time. So what Superman has is the power to see through (most) objects, and it was named “X-ray vision” because those who named it had no idea what else to call it. No actual X-rays are involved, however.

@SavoirFaire Makes sense. I’m glad he isn’t flying around irradiating everyone he meets, at least.

Or…he could squint like the near sighted kids who can’t see the board.