Visible Broadband Imager (VBI)

Mission

The mission of the Visible Broadband Imager (VBI) is to record images with the highest possible spatial and temporal resolution available for the Daniel K. Inouye Solar Telescope, at a number of specified wavelengths in the range from 390 nm to 860 nm.

Description

The VBI is optically located behind the DKIST Adaptive Optics (AO) system and consists of two camera channels that are operated individually, but can be synchronized. Its optical design optimally preserves the Strehl ratio of the image provided by the telescope, under the constraint of scientific requirements. Each channel has high optical throughput at all science wavelengths that span a range of diagnostics within the solar photosphere and chromosphere. The VBI allows for image reconstruction to improve image quality beyond what is provided by the telescope adaptive optics system. To maximize the field of view (FOV) at the required spatial sampling, the VBI has large format arrays in its image plane; however, current sensor technology has not progressed enough so that the VBI still needs to move its cameras to field sample DKIST’s complete FOV.

Technical Details at a Glance

Spatial Sampling and Field of View

• As a post-AO instrument, VBI is fully and routinely supported by the DKIST AO system

Spatial Sampling

• VBI blue channel: 0.011 arcsec/pix
  [theoretical spatial resolution of DKIST @ λ = 430.5 nm: 0.022 arcsec]

• VBI red channel: 0.017 arcsec/pix
  [theoretical spatial resolution of DKIST @ λ = 656.3 nm: 0.034 arcsec]

• NOTE: The effective spatial resolution in VBI images can be limited by atmospheric turbulence that affects performance of adaptive optics system and post-facto image reconstruction algorithms.

Field of View

• Full optical field: 2×2 arcmin² (i.e. the full post-AO DKIST field of view).

• Field in single image is limited by the 4k×4k detector.

  • VBI blue channel: 45×45 arcsec²

  • VBI red channel: 69×69 arcsec²

• The full optical field of views in each VBI channel are accessible by field sampling.

Spectral Range and Resolution

• NOTE: The actual wavelengths accessible by VBI channels depends on the configuration of the Facility Instrument Distribution Optics (FIDO) employed, which can limit the usable filters in the VBI channels.

Temporal Cadence

• The VBI acquires, in its default mode of operation, sets of images and uses these sets to compute a single reconstructed image, discarding the original images.

• Within each channel, images at multiple wavelengths and field positions (when field sampling is used) are acquired in series.

Reconstructed images

• 3.4 seconds for images with same physical FOV (single or multiple λ)

  • 2.667 seconds are for data acquisition: 80 frames acquired at a rate of 30 Hz

  • 0.733 seconds are for mechanism move times (camera and/or filter wheel motion)

• Full optical FOV

  • VBI blue channel: 3×3 tiling of the full optical FOV within 9 × (2.667 + 0.733) seconds = 30.6 seconds

  • VBI red channel: 2×2 tiling for full optical FOV within (4+1 center field) × (2.667 + 0.733) seconds = 17 seconds

Raw images

• NOTE: Raw VBI image data is currently not available.

Polarimetric Capabilities

• None

Photometric Capabilities

• Relative photometry: 2×10^-2 I_mean

Instrument Modes

• Single physical FOV data acquisition, or partial or full optical FOV data acquisition via field sampling.

• Reconstructed images at any wavelength.

• Frame Selection, for data volume reduction.

• Simultaneous, synchronized (accuracy: 10 ms) and unsynchronized data acquisition options between VBI red and VBI blue channel:

  1. Fixed synchronization: synchronization between Blue and Red channel at the beginning of acquisition at each wavelength in a sequence.

  2. Loose synchronization: synchronization between Blue and Red channel at the beginning of an acquisition sequence consisting of multiple selected wavelengths.

  3. No synchronization between Blue and Red channel.

Example Modes of Operation

Field Sampling Modes

• Field Sampling mode: all (spiral)

  • Channel: VBI blue

  • no frame selection

  • Wavelength: H-β

  • Data Center DataSet Link

Individual fields	Stitched field

Individual fields	Stitched field
Open Individual reconstructed VBI blue images, acquired in (spiral) field sampling mode.	Open Stitched full VBI blue field of view, projected into the correct solar coordinate frame on the sun using the DKIST Data Center Tools.

• Central field only

  • Channel: VBI red

  • no frame selection

  • Wavelength: H-α

  • Data Center DataSet Link

Example time sequence

Example time sequence
Open Example of a high cadence center field only time-sequence in the VBI red channel.

Synchronization Modes

Example 1: Fixed Synchronization

The beginning of each data set acquisition (80 frames) for a wavelength and field sample is synchronized between the two channels. When the full field of view is sampled in each channel, the start of the acquisition sequence is synchronized between the channels. When only the center of the field of view is acquired with a single sample in each channel (example below), in speckle mode the acquisitions start and end quasi-simultaneous.

Open

Example 2: Loose Synchronization

In loose synchronization, the beginning of a cycle - that can consist of a variety of combinations of wavelengths and field of view sizes - is started simultaneously. Below an example with a single wavelength acquired over the full field of view in the first channel is synchronized at the start with the acquisition of two wavelengths over the full field of view in the second channel.

Open

Example 3: No Synchronization

Wavelengths and field of view acquisitions are not synchronized between the two channels.

Open

Publications

• Bahauddin, S. M., Fischer, C. E., Rast, M. P., et al., “Observations of Locally Excited Waves in the Low Solar Atmosphere Using the Daniel K. Inouye Solar Telescope“, The Astrophysical Journal Letters, 971, 1, L1 (2024)

• Kuridze, D., Uitenbroek, H. Wöger, F., et al., “Insight into the Solar Plage Chromosphere with DKIST“, The Astrophysical Journal, 965, 1, 15 (2024)

• Rimmele, T., Tritschler, A., Parraguez, A., et al., “The US National Science Foundation Daniel K. Inouye Solar Telescope operations commissioning: results and lessons learned“, Ground-based and Airborne Telescopes X, Proc SPIE 13094: 130940Y (2024)

• Fischer, C., Woeger, F., Rimmele, T., et al., “Chromospheric horizontal propagating shock waves revealed by fast cadence imaging in Ca II K with DKIST's Visible Broadband Imager“, American Astronomical Society, SPD Meeting #54, #407.03 (2023)

• Kuridze, D. Woeger, F., Fischer, C., et al., “DKIST observations of the fine-scale chromospheric structures“, American Astronomical Society, SPD Meeting #54, #407.02 (2023)

• da Silva Santos, J. M., Reardon, K., Cauzzi, G., et al., “Magnetic Fields in Solar Plage Regions: Insights from High-sensitivity Spectropolarimetry“, The Astrophysical Journal Letters, 954, 2 (2023)

• Woeger, F., Rimmele, T. R., Tritschler, A., Fischer, C., “Sunspots at 0.03" Resolution”, AGU Fall Meeting 2022, SH12D-1472 (2022)

• Rimmele, T., Warner, M., Casini, R., et al., “The National Science Foundation's Daniel K. Inouye Solar Telescope: status and first results“, Ground-based and Airborne Telescopes IX, Proc SPIE 12182: 121820Z (2022)

• Rimmele, T., Woeger, F., Tritschler, A., et al., “Ground-based instrumentation and observational techniques“, 44th COSPAR Scientific Assembly, 44, E2.4-0001-22

• Wöger, F., Rimmele, T., Ferayorni, A. et al., “The Daniel K. Inouye Solar Telescope(DKIST)/Visible Broadband Imager (VBI)”, Solar Physics 296, 145 (2021)

• Rimmele, T.R., Warner, M., Keil, S.L., et al., “The Daniel K. Inouye Solar Telescope – Observatory Overview“, Solar Physics 295, 172 (2020)

• Woeger, F., Rimmele, T., et al., “DKIST First-light Instrumentation“, American Astronomical Society meeting #238, #106.02 (2021)

• Rimmele, T., Woeger, F., Tritschler, A., et al., “The National Science Foundation's Daniel K. Inouye Solar Telescope — Status Update“, American Astronomical Society meeting #238, #106.01 (2021)

• Beard, A., Wöger, F., Ferayorni, A., “Real-time speckle image processing with the DKIST”, Software and Cyberinfrastructure for Astronomy VI, Proc SPIE 11452: 114521X (2020)

• Warner, M., Rimmele, T. R., Martinez Pillet, V., et al. “Construction update of the Daniel K. Inouye Solar Telescope project“, Ground-based and Airborne Telescopes VII, 10700: 107000V (2018)

• Peck, C. L., Wöger, F., Marino, J., “Influence of speckle image reconstruction on photometric precision for large solar telescopes“, Astronomy & Astrophysics, 607, A83 (2017)

• Tritschler, A., Rimmele, T. R., Berukoff, S., et al., “Daniel K. Inouye Solar Telescope: High-resolution observing of the dynamic Sun", Astronomische Nachrichten, 337, 10 (2016)

• Ferayorni, A., Beard, A., Gregory, B. S., et al., “Bottom-up laboratory testing of the DKIST Visible Broadband Imager (VBI)“, Modeling, Systems Engineering, and Project Management for Astronomy VI, Proc SPIE 9911: 991106 (2016)

• Sekulic, P., Gregory, S. B., Hegwer, S. L., et al., “DKIST visible broadband imager alignment in laboratory: first results“, Instrumentation for Astronomy VI, Proc SPIE 9908: 99085A (2016)

• Beard, A., Cowan, B., and Ferayorni, A., “DKIST visible broadband imager data processing pipeline“, Software and Cyberinfrastructure for Astronomy III, Proc SPIE 9152: 91521J (2014)

• Elmore, D. F., Rimmele, T. R., Casini, R., et al., “The Daniel K. Inouye Solar Telescope first light instruments and critical science plan“, Ground-based and Airborne Instrumentation for Astronomy V, Proc SPIE 9147: 914707 (2014)

• Wöger, F., “DKIST Visible Broadband Imager Interference Filters“, Ground-based and Airborne Instrumentation for Astronomy V, Proc SPIE 9147: 91479I (2014)

• Berger, T., and ATST Science Team, “The ATST Instrumentation suite: capabilities, synergies, and science goals“, American Astronomical Society, SPD meeting #44, #400.02 (2013)

• Ferayorni, A., “Instrument control software for the Visible Broadband Imager using ATST common services framework and base“, Software and Cyberinfrastructure for Astronomy II, Proc SPIE 8451: 845113 (2012)

• McBride, W. R., Wöger, F., Hegwer, S. L., et al., “ATST visible broadband imager“, Ground-based and Airborne Instrumentation for Astronomy IV, Proc SPIE 8446: 84461B (2012)

• Wöger, F., and Ferayorni, A., “Accelerated speckle imaging with the ATST visible broadband imager“, Software and Cyberinfrastructure for Astronomy II, Proc SPIE 8451: 84511C (2012)

• Wöger, F., McBride, W. R., Ferayorni, A., et al., “The Visible Broadband Imager: The Sun at High Spatial and Temporal Resolution“, 2nd ATST-EAST Workshop in Solar Physics: Magnetic Fields from the Photosphere to the Corona, ASP Conf Ser 463: 431 (2012)

• Wöger, F., Tritschler, A., Uitenbroek, H., and Rimmele, T. R., “The Visible Broadband Imager: The Sun at High Spatial and Temporal Resolution“, American Astronomical Society, SPD meeting #42, #20.01 (2011).

• Wöger, F., Uitenbroek, H., Tritschler, A., et al., “The ATST visible broadband imager: a case study for real-time image reconstruction and optimal data handling“, Ground-based and Airborne Instrumentation for Astronomy III, Proc SPIE 7735: 773521 (2010)

• Uitenbroek, H., Tritschler, A., An, H. K., and Berger, T., “The visible-light broad-band imager for ATST: preliminary design“, Ground-based and Airborne Instrumentation for Astronomy, Proc SPIE 6269: 626961 (2006)

Principal Investigator

Dr. Friedrich Wöger
National Solar Observatory

Instrument Performance Calculator

• VBI IPC Tool & Manual Zip File

DKIST Instruments

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