Current high resolution consumer cameras can capture images with pixel counts in the tens of millions. There is an increasing interest in producing images with billions of pixels as a gigapixel image contains a tremendous amount of information such that one can explore minute details of the scene. Gigapixel images capture details that are orders of magnitude greater than that seen by the human eye, revealing information that was completely imperceptible to the photographer at the time of capturing the image.
At present, highly specialized gigapixel imaging systems are being developed for aerial surveillance and for special-purpose large format imaging systems, but there are no commercially available cameras capable of producing gigapixel images. While complementary metal-oxide-semiconductor and charge-coupled device technologies can provide imaging sensors with pixels in the one micron range and while it is within the reach of such manufacturing technologies to produce imaging sensors with one billion pixels, it remains a difficult challenge to design and manufacture lenses that have the resolving power to match the resolution of such a sensor. This is due to the number of resolvable points for a lens, which is sometimes referred to as the space-bandwidth product (SBP), being fundamentally limited by geometrical aberrations. Ideally, lenses are diffraction limited so that increasing the scale of lens while keeping field of view (FOV) fixed increases the space-bandwidth product. However, due to geometrical aberrations, the space-bandwidth product reaches a limit.
One approach for increasing the space-bandwidth product with regard to the fundamental limit is to accept the loss in resolution and increase the size of the sensor. For example, consider the commercially available F/8 500 mm focal length Apo-Symmar lens manufactured by Schneider Optics. If this lens was diffraction limited, it may be capable of resolving a gigapixel image on a 5″×5″ sensor. However, because of geometrical aberrations, a sensor size of about 12″×12″ is necessary to resolve an image having at least one billion pixels.
Another approach for increasing the space-bandwidth product is to increase complexity as a lens is scaled up. The introduction of more optical surfaces increases the degrees of freedom in lens optimization, which can be used to reduce geometric aberrations and achieve diffraction limited performance. Consider the F/4 75 mm focal length lens shown in FIG. 1. The lens is diffraction limited over a 60° field of view so that a gigapixel image can be resolved on a 75 mm×75 mm surface, which is much smaller than for the Apo-Symmar lens described above. This increase in performance, however, comes at a great cost. The design consists of eleven different optical elements, ranging from 60-100 mm in diameter, resulting in a lens that is both expensive to produce and difficult to align.
Accordingly, it is desirable to provide camera systems and methods that overcome these and other deficiencies of the prior art.