Would it be feasible to create a large photo sensor panel for a light gathering telescope?

Question

I've been thinking about how costly it is to manufacture the large mirrors used in optical telescopes and whether or not it would be feasible to have instead a large panel of photo sensors similar but != the sensor in a digital camera. I know it sounds silly, but there must be a better way than just building bigger and bigger mirrors to get a better picture of the universe. What could be some alternatives?

Answer 1

A larger photo sensor would, indeed, be cool...
Remember, though, that a telescope's light- gathering power doesn't come from it's sensors, it comes from it's aperture!
The photo sensors don't have to be large, they just need to be fine enough (i.e. more mega- or giga- pixels) to deliver the spectacular images we have all come to expect.

Answer 2

I cannot imagine why kind of photo sensor you are thinking about. All I can imagine is a CCD or CMOS sensor like a digital camera or chemical film. But in any case, sensors only detect light, not make images. You need a lens or mirror to make an image. You can use a lens to project an image on plain white paper, and if it is something bright enough, like the Sun, you can just look at it on the paper like you would a slide show. And if you want a brighter image with more detail, you need a bigger lens. A bigger one gathers more light but it also makes a more detailed image. Due to the wave nature of light, there is a limit to the detail that can be distinguished, or resolved as they say. To resolve detail half as large you need a mirror twice the diameter. It is a law of physics called diffraction.

Answer 3

What you really need is multiple smaller mirrors combined to form an array that is equivalent of a large single mirror. This has been done! Each of the Keck telescopes consists of six smaller mirrors and the sum has the power of a ten meter telescope. This is the only way to go bigger than 6-7 meter telescopes

Answer 4

The whole point is to gather light and concentrate it. Your photosensor panel wouldn't do this, and would cost far more to manufacture than a telescope mirror.

Our current mirror fabrication technology can't go much bigger than 10 meters in diameter. So they're making multiple telescopes work together. Radio astronomers have been doing this for years; now the optical astronomers are starting to play with interferometry.

Answer 5

A photo sensor cannot focus the light to form an image. It can only record the image once it has been formed by another means.

Adolph