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NICI Components

The NICI light-path traverses the following optical elements:

Fiber Optic Calibration Source
Adaptive Optics (AO) Relay and Wavefront Sensor (WFS)
Focal Plane Mask Wheel
Spider Mask and Pupil Mask Wheels
Dichroic/Beamsplitter Wheel
Filter Wheels, 1 per channel
InSb Detectors, 1 per channel

Characteristics and Read Modes

These components are arranged as shown in this block diagram. For additional drawings see the NICI Optical Diagrams page.

Fiber Optic Calibration Source

The Calibration Source is a 4-position slide carrying single-mode fibers for AO and science detector characterization and calibration.

AO Relay

The AO relay is an 85-element curvature AO system with an APD (Avalanche PhotoDiode) wavefront sensor.

Pre-Dichroic Optics

After the AO system, the beam reaches the Focal Plane Mask wheel which provides coronagraphic masks. The beam then enters the science camera cryostat and is collimated by an off-axis paraboloid. All powered optics in the NICI science camera are mirrors to minimize ghosting. The collimator forms an image of the pupil on the Spider Mask and Pupil Mask wheels, which stop down the pupil image. The beam is then split by the Dichroic/Beamsplitter wheel into the two science channels: Channel 1 (or "Red") which receives the transmitted light and Channel 2 (or "Blue") which receives the reflected light.

Post-Dichroic Dual Channels

After the beam-splitter, the light in each channel passes through a Filter wheel before proceeding to the camera mirrors and detectors. In addition, Channel 1 has a pupil imaging capability used primarily to align the science camera's pupil with the telescope.

Created 1 July 2005; B. Rodgers
Updated 19 July 2005; T. Hayward