A little wonder, every day

Micrometres that blurred Hubble’s vision

Документальне фото огляду головного дзеркала «Хаббла», NASA / Documentary photograph of Hubble’s primary mirror inspection, NASA.

Зображення M100 показують зміну якості до й після коригування оптики 1993 року / M100 images show the change before and after the 1993 optical correction; scientific image comparison.

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Документальне фото огляду головного дзеркала «Хаббла», NASA / Documentary photograph of Hubble’s primary mirror inspection, NASA.

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Hubble’s primary mirror was extremely smooth but had the wrong shape: the deviation near its edge was about 2.2 micrometres. Spherical aberration prevented light from reaching the intended focus, blurring the early images. During the 1993 servicing mission astronauts installed corrective optics and a new camera with its own compensation. The primary mirror itself was not reground in orbit. It illustrates how a small geometric error can have a large optical consequence.