NIRCam Optics

The JWST NIRCam optical elements include dichroics, filters, weak lenses, grisms, as well as coronagraph occulting masks and Lyot stops.

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NIRCam's 2 modules (A and B) receive light relatively close to on-axis from the JWST Optical Telescope Element (OTE), as shown in the field of view in Figure 1.

Figure 1. NIRCam modules footprint in the JWST field of view

NIRCam modules in the JWST field of view

NIRCam's 10 detectors are labeled. Each module has 5 detectors: 4 for the short wavelength channel and one for the long wavelength channel. Coronagraph images are projected onto the detectors by an optical wedge (when needed).


Optical path

From the NIRCam pickoff mirror, within each module, light passes through these components in the following order:

Figure 2. NIRCam optical train

NIRCam optical train

Upper half of figure: NIRCam optical train
Lower half of figure: The detector view, at the focal plane assembly (FPA), of incoming light with and without a coronagraph wedge in the optical path. The coronagraph wedges are included on Lyot stop elements on each pupil wheel. © Somerstein & Truong 2005.
Figure 3. NIRCam optical train in one module

NIRCam optical train in one module

© Greenhouse et al. 2011.


References

Greenhouse, M. et al. 2011, SPIE 814606G
Status of the James Webb Space Telescope integrated science instrument module system

Somerstein, S. F., Truong, G.D. 2005, SPIE 590407
NIRCam optical calibration sources




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