Hubble Space Telescope · 1995–2002
Advanced Camera for Surveys
Invented the aberrated-beam coronagraph flown in ACS; IDT member.
- Role
- Inventor and proposer of the ACS coronagraph; ACS Investigation Definition Team member
- Concept
- Occulting spots in Hubble's uncorrected, spherically aberrated beam, ahead of the corrective optics
- Masks
- 1.8″ and 3.0″ occulting spots; Lyot stop at the reimaged pupil masking the OTA's diffracting edges; 0.8″ × 5″ occulting finger
- Flight
- Installed in Servicing Mission 3B, March 2002; High Resolution Channel
- Primary source
- Burrows, “The Advanced Camera Coronagraph for HST” (abstract, written when ACS was due for 1999 installation)
Chris invented and proposed the coronagraph flown in the High Resolution Channel of ACS. Its key idea was to put the occulting spots in Hubble's aberrated beam, at the circle of least confusion, before the ACS mirrors that correct the primary's spherical aberration. A pupil image is formed after the spot, where a Lyot stop blocks light diffracted by the telescope's mirror edges, secondary spiders and support pads, and the corrective optics then restore a sharp image.
Placing the mask in the aberrated beam let a coronagraph be added after ACS construction had begun, without redesigning the camera's optical train. In his own description at the time, the coronagraph “operates by inserting a field stop into the aberrated beam at the circle of least confusion,” with diffracted light “caught by a pupil plane Lyot stop” and the residual set by mid-scale ripple on the HST mirrors. He argued it would be Hubble's first chance to exploit its full dynamic range, imaging protostellar and debris disks whose structure can reveal planets. It was used for the β Pictoris and AU Microscopii debris disks, HD 141569A, and the host of quasar 3C 273.
From the archive
Papers
- 2006