NIRCam (Near-InfraRed Camera) is an instrument aboard the

James Webb Space Telescope The James Webb Space Telescope (JWST) is a space telescope which conducts infrared astronomy. As the largest optical telescope in space, its high resolution and sensitivity allow it to view objects too old, distant, or faint for the Hubble Spa ...

. It has two major tasks, as an imager from 0.6 to 5 micron wavelength, and as a wavefront sensor to keep the 18-section mirrors functioning as one. In other words, it is a camera and is also used to provide information to align the 18 segments of the primary mirror. It is an infrared camera with ten mercury-cadmium-telluride (HgCdTe) detector arrays, and each array has an array of 2048×2048 pixels. The camera has a field of view of 2.2×2.2 arc minutes with an angular resolution of 0.07 arcsec at 2 microns. NIRCam is also equipped with coronagraphs, which helps to collect data on exoplanets near stars. It helps with imaging anything next to a much brighter object, because the coronagraph blocks that light. NIRCam is housed in the

Integrated Science Instrument Module Integrated Science Instrument Module (ISIM) is a component of the James Webb Space Telescope, a large international infrared space telescope launched on . ISIM is the heart of the JWST, and holds the main science payload which includes four scienc ...

(ISIM), to which it is attached by struts. It is designed to operate at , so it can detect

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

radiation at this wavelength.NIRCam Instrument Overview
/ref> It is connected to the ISIM by struts and thermal straps connect to heat radiators, which helps maintain its temperature. The Focal Plane Electronics operated at 290 K. NIRCam should be able to observe objects as faint as magnitude +29 with a 10,000-second exposure (about 2.8 hours). It makes these observations in light from 0.6 (600 nm) to 5 microns (5000 nm) wavelength. It can observe in two fields of view, and either side can do imaging, or from the capabilities of the wave-front sensing equipment, spectroscopy. The wavefront sensing is much finer than the thickness of an average human hair. It must perform at an accuracy of at least 93 nanometers and in testing it has even achieved between 32 and 52 nm. A human hair is thousands of nanometers across.

Main

Components

Wavefront sensor In physics, the wavefront of a time-varying ''wave field'' is the set (locus) of all points having the same '' phase''. The term is generally meaningful only for fields that, at each point, vary sinusoidally in time with a single temporal frequ ...

components include: *Dispersed Hartmann sensors *

Grism A grism (also called a grating prism) is a combination of a prism and grating arranged so that light at a chosen central wavelength passes straight through. The advantage of this arrangement is that one and the same camera can be used both for imag ...

s *Weak lenses Parts of NIRCam: *Pick-off mirror * Nircam modules

Coronograph A coronagraph is a telescopic attachment designed to block out the direct light from a star so that nearby objects – which otherwise would be hidden in the star's bright glare – can be resolved. Most coronagraphs are intended to view ...

*First-fold mirror *

Collimator A collimator is a device which narrows a beam of particles or waves. To narrow can mean either to cause the directions of motion to become more aligned in a specific direction (i.e., make collimated light or parallel rays), or to cause the spati ...

lenses *Dichroic

beam splitter A beam splitter or ''beamsplitter'' is an optical device that splits a beam of light into a transmitted and a reflected beam. It is a crucial part of many optical experimental and measurement systems, such as interferometers, also finding wide ...

*Longwave filter wheel *Longwave camera lens group *Longwave focal plane *Shortwave filter wheel assembly *Shortwave camera lens group *Shortwave fold mirror *Pupil imaging lens *Shortwave focal plane

Overview

NIRCam has two complete optical systems for redundancy. The two sides can operate at the same time, and view two separate patches of sky; the two sides are called side A and side B. The lenses used in the internal optics are triplet

refractor A refracting telescope (also called a refractor) is a type of optical telescope that uses a lens (optics), lens as its objective (optics), objective to form an image (also referred to a dioptrics, dioptric telescope). The refracting telescope d ...

s. The lens materials are

lithium fluoride Lithium fluoride is an inorganic compound with the chemical formula LiF. It is a colorless solid, that transitions to white with decreasing crystal size. Although odorless, lithium fluoride has a bitter-saline taste. Its structure is analogous to ...

(LiF), a

barium fluoride Barium fluoride (BaF2) is an inorganic compound with the formula BaF2. It is a colorless solid that occurs in nature as the rare mineral frankdicksonite. Under standard conditions it adopts the fluorite structure and at high pressure the PbCl2 s ...

(BaF₂) and

zinc selenide Zinc selenide (ZnSe) is a light-yellow, solid compound comprising zinc (Zn) and selenium (Se). It is an intrinsic semiconductor with a band gap of about 2.70 eV at . ZnSe rarely occurs in nature, and is found in the mineral that was named af ...

(ZnSe). The triplet lenses are

collimating A collimated beam of light or other electromagnetic radiation has parallel ray (optics), rays, and therefore will spread minimally as it propagates. A perfectly collimated light beam, with no beam divergence, divergence, would not disperse with di ...

optics. The biggest lens has 90 mm of clear aperture. The observed wavelength range is broken up into a short wavelength and a long wavelength band. The short wavelength band goes from 0.6 to 2.3 microns and the long wavelength band goes from 2.4 to 5 microns; both have the same field of view and access to a coronagraph. Each side of the NIRCam views a 2.2 arcminute by 2.2 arcminute patch of sky in both the short and long wavelengths; however, the short wavelength arm has twice the resolution. The long wavelength arm has one array per side (two overall), and the short wavelength arm has four arrays per side, or 8 overall. Side A and Side B have a unique field of view, but they are adjacent to each other. In other words, the camera looks at two 2.2 arcminute wide fields of view that are next to each other, and each of these views is observed at short and long wavelengths simultaneously with the short wavelength arm having twice the resolution of the longer wavelength arm.

Design and manufacturing

The builders of NIRCam are the University of Arizona, company

Lockheed Martin The Lockheed Martin Corporation is an American aerospace, arms, defense, information security, and technology corporation with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta in March 1995. It ...

, and

Teledyne Technologies Teledyne Technologies Incorporated is an American industrial conglomerate. It was founded in 1960, as Teledyne, Inc., by Henry Singleton and George Kozmetsky. From August 1996 to November 1999, Teledyne existed as part of the conglomerate Al ...

, in cooperation with the U.S. Space agency, NASA. Lockheed Martin tested and assembled the device. Teledyne Technologies designed and manufactured the ten mercury-cadmium-telluride (HgCdTe) detector arrays. NIRCam was completed in July 2013 and it was shipped to Goddard Spaceflight Center, which is the NASA center managing the JWST project. NIRCam's four major science goals include:

Electronics

Webb Instruments Perfected to Microscopic Levels (14486243743)

Data from the image sensors (Focal Plane Arrays) is collected by the Focal Plane Electronics and sent to the ISIM computer. The data between the FPE and the ISIM computer is transferred by

SpaceWire SpaceWire is a spacecraft communication network based in part on the IEEE 1355 standard of communications. It is coordinated by the European Space Agency (ESA) in collaboration with international space agencies including NASA, JAXA, and RKA. ...

connection. There are also Instrument Control Electronics (ICE). The Focal Plane Arrays contain 40 million pixels. The FPE provides or monitors the following for the FPA: *Regulated power *Output

data synchronization Data synchronization is the process of establishing consistency between source and target data stores, and the continuous harmonization of the data over time. It is fundamental to a wide variety of applications, including file synchronization and m ...

Temperature control Temperature control is a process in which change of temperature of a space (and objects collectively there within), or of a substance, is measured or otherwise detected, and the passage of heat energy into or out of the space or substance is ad ...

*Operational mode controls *Image

data conditioning Data conditioning is the use of data management and optimization techniques which result in the intelligent routing, optimization and protection of data for storage or data movement in a computer system. Data conditioning features enable enterpr ...

*Image data amplification *Image data

digitization DigitizationTech Target. (2011, April). Definition: digitization. ''WhatIs.com''. Retrieved December 15, 2021, from https://whatis.techtarget.com/definition/digitization is the process of converting information into a Digital data, digital (i ...

Filters

NIRcam includes filter wheels that allow the light coming in from the optics to be sent through a

filter Filter, filtering or filters may refer to: Science and technology Computing * Filter (higher-order function), in functional programming * Filter (software), a computer program to process a data stream * Filter (video), a software component tha ...

before it is recorded by the sensors. The filters have a certain range in which they allow light to pass, blocking the other frequencies; this allows operators of NIRCam some control over what frequencies are observed when making an observation with the telescope. By using multiple filters the redshift of distant galaxies can be estimated by photometry. NIRcam filters: ;Short wavelength channel (0.6–2.3 µm): *F070W - General purpose *F090W - General purpose *F115W - General purpose *F140M - Cool stars, , *F150W - General purpose *F150W2 - Blocking filter for F162M, F164N, and DHS *F162M - Cool Stars, off-band for *F164N -

eII EII may refer to: People * Edward II of England (1284–1327) * Elizabeth II (1926–2022), Queen of the United Kingdom and the other Commonwealth realms Other uses * Earth Island Institute, an American environmental group * Edward II (band), ...

*F182M - Cool stars, , *F187N - Pa-alpha *F200W - General purpose *F210M - , *F212N - ;Long wavelength channel (2.4–5.0 µm): *F250M - , continuum *F277W - General purpose *F300M - Water ice *F322W2 - Background min. Primarily used w/ grisms. Blocking filter for F323N. *F323N - *F335M - PAH, *F356W - General purpose *F360M - Brown dwarfs, planets, continuum *F405N - Br-alpha *F410M - Brown dwarfs, planets, , *F430M - , *F444W - General purpose. Blocking filter for F405N, F466N, F470N. *F460M - CO *F466N - CO *F470N - *F480M - Brown dwarfs, planets, continuum

Labeled diagram

References

External links

JWST NASA website - NIRCamNIRCamNIRCam gallery on FlickrNIRCam pocket guide
(2 page .pdf)
Slitless spectroscopy with the James Webb Space Telescope Near-Infrared Camera (JWST NIRCam)
{{Jwstnav James Webb Space Telescope instruments Space imagers