Abstract

To reduce the level of stray light in a new-generation externally occulted space coronagraph, we consider new concepts for its external occulter and its associated diaphragm and report extended measurements of their light-rejection properties. The experimental setup, which includes an artificial Sun, uses both photometric and CCD imaging techniques and permits the study of the sensitivity to misalignement of the instrument’s performance. Conic occulters that have either a multithreaded or a polished surface are found to give performances superior to those of the classical three-disk system and further are highly tolerant to misalignement. Serrated diaphragms outperform circular ones, as the bulk of the diffracted light is diverted from the coronagraphic objective.

© 2000 Optical Society of America

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References

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  1. G. Newkirk, D. Bohlin, “Reduction of scattered light in the coronagraph,” Appl. Opt. 2, 131–140 (1963).
    [CrossRef]
  2. J. W. Evans, “A photometer for measurement of sky brightness near the Sun,” J. Opt. Soc. Am. 38, 1083–1085 (1948).
    [CrossRef] [PubMed]
  3. J. D. Purcell, M. J. Koomen, “Coronagraph with improved scattered-light properties,” J. Opt. Soc. Am. 52, 596–597 (1962).
  4. B. Fort, C. Forel, G. Spaak, “The reduction of scattered light in an external occulting disk coronagraph,” Astron. Astrophys. 63, 243–246 (1978).
  5. M. J. Koomen, C. R. Detwiler, G. E. Brueckner, H. W. Cooper, T. Tousey, “White light coronagraph in OSO-7,” Appl. Opt. 14, 743–751 (1975).
    [CrossRef] [PubMed]
  6. R. M. MacQueen, J. T. Gosling, E. Hildner, R. H. Munro, A. I. Poland, C. L. Ross, “The High Altitude Observatory white light coronagraph,” in Instrumentation in Astronomy II, D. H. Menzel, L. Larmore, D. Crawford, eds., Proc. SPIE44, 207–212 (1974).
    [CrossRef]
  7. N. R. Sheeley, D. J. Michels, R. A. Howard, M. J. Koomen, “Initial observations with the Solwind coronagraph,” Astrophys. J. 237, L99–L101 (1980).
    [CrossRef]
  8. R. M. MacQueen, A. Csoeke-Poeckh, E. Hildner, L. House, R. Reynolds, A. Stanger, H. Tepoel, W. Wagner, “The High Altitude Observatory Coronagraph/Polarimeter on the Solar Maximum Mission,” Solar Phys. 65, 91–107 (1980).
    [CrossRef]
  9. G. E. Brueckner, R. A. Howard, M. J. Koomen, C. M. Korendyke, D. J. Michels, D. G. Socker, K. P. Dere, P. L. Lamy, A. Llebaria, M.-V. Bout, R. Schwenn, G. M. Simnett, D. K. Bedford, D. J. Eyles, “The Large Angle Spectroscopic Coronagraph (LASCO),” Solar Phys. 162, 1–2, 357–402 (1995).
  10. S. Koutchmy, M. Belmahdi, “Improved measurements of scattered light levels behind occulting systems,” J. Opt. 18, 5–6, 265–269 (1987).
  11. D. Bohlin, NASA Headquarters, 300 E Street, SW, Washington, D.C. (personal communication, 15October1989).
  12. A. V. Lenskii, “Theoretical assessment of efficiency of coronagraph external occulting systems,” Astron. Zh. 58, 648–659 (1981) [Sov. Astron. 25(3), 366–372 (1981)].

1995 (1)

G. E. Brueckner, R. A. Howard, M. J. Koomen, C. M. Korendyke, D. J. Michels, D. G. Socker, K. P. Dere, P. L. Lamy, A. Llebaria, M.-V. Bout, R. Schwenn, G. M. Simnett, D. K. Bedford, D. J. Eyles, “The Large Angle Spectroscopic Coronagraph (LASCO),” Solar Phys. 162, 1–2, 357–402 (1995).

1987 (1)

S. Koutchmy, M. Belmahdi, “Improved measurements of scattered light levels behind occulting systems,” J. Opt. 18, 5–6, 265–269 (1987).

1981 (1)

A. V. Lenskii, “Theoretical assessment of efficiency of coronagraph external occulting systems,” Astron. Zh. 58, 648–659 (1981) [Sov. Astron. 25(3), 366–372 (1981)].

1980 (2)

N. R. Sheeley, D. J. Michels, R. A. Howard, M. J. Koomen, “Initial observations with the Solwind coronagraph,” Astrophys. J. 237, L99–L101 (1980).
[CrossRef]

R. M. MacQueen, A. Csoeke-Poeckh, E. Hildner, L. House, R. Reynolds, A. Stanger, H. Tepoel, W. Wagner, “The High Altitude Observatory Coronagraph/Polarimeter on the Solar Maximum Mission,” Solar Phys. 65, 91–107 (1980).
[CrossRef]

1978 (1)

B. Fort, C. Forel, G. Spaak, “The reduction of scattered light in an external occulting disk coronagraph,” Astron. Astrophys. 63, 243–246 (1978).

1975 (1)

1963 (1)

1962 (1)

J. D. Purcell, M. J. Koomen, “Coronagraph with improved scattered-light properties,” J. Opt. Soc. Am. 52, 596–597 (1962).

1948 (1)

Bedford, D. K.

G. E. Brueckner, R. A. Howard, M. J. Koomen, C. M. Korendyke, D. J. Michels, D. G. Socker, K. P. Dere, P. L. Lamy, A. Llebaria, M.-V. Bout, R. Schwenn, G. M. Simnett, D. K. Bedford, D. J. Eyles, “The Large Angle Spectroscopic Coronagraph (LASCO),” Solar Phys. 162, 1–2, 357–402 (1995).

Belmahdi, M.

S. Koutchmy, M. Belmahdi, “Improved measurements of scattered light levels behind occulting systems,” J. Opt. 18, 5–6, 265–269 (1987).

Bohlin, D.

G. Newkirk, D. Bohlin, “Reduction of scattered light in the coronagraph,” Appl. Opt. 2, 131–140 (1963).
[CrossRef]

D. Bohlin, NASA Headquarters, 300 E Street, SW, Washington, D.C. (personal communication, 15October1989).

Bout, M.-V.

G. E. Brueckner, R. A. Howard, M. J. Koomen, C. M. Korendyke, D. J. Michels, D. G. Socker, K. P. Dere, P. L. Lamy, A. Llebaria, M.-V. Bout, R. Schwenn, G. M. Simnett, D. K. Bedford, D. J. Eyles, “The Large Angle Spectroscopic Coronagraph (LASCO),” Solar Phys. 162, 1–2, 357–402 (1995).

Brueckner, G. E.

G. E. Brueckner, R. A. Howard, M. J. Koomen, C. M. Korendyke, D. J. Michels, D. G. Socker, K. P. Dere, P. L. Lamy, A. Llebaria, M.-V. Bout, R. Schwenn, G. M. Simnett, D. K. Bedford, D. J. Eyles, “The Large Angle Spectroscopic Coronagraph (LASCO),” Solar Phys. 162, 1–2, 357–402 (1995).

M. J. Koomen, C. R. Detwiler, G. E. Brueckner, H. W. Cooper, T. Tousey, “White light coronagraph in OSO-7,” Appl. Opt. 14, 743–751 (1975).
[CrossRef] [PubMed]

Cooper, H. W.

Csoeke-Poeckh, A.

R. M. MacQueen, A. Csoeke-Poeckh, E. Hildner, L. House, R. Reynolds, A. Stanger, H. Tepoel, W. Wagner, “The High Altitude Observatory Coronagraph/Polarimeter on the Solar Maximum Mission,” Solar Phys. 65, 91–107 (1980).
[CrossRef]

Dere, K. P.

G. E. Brueckner, R. A. Howard, M. J. Koomen, C. M. Korendyke, D. J. Michels, D. G. Socker, K. P. Dere, P. L. Lamy, A. Llebaria, M.-V. Bout, R. Schwenn, G. M. Simnett, D. K. Bedford, D. J. Eyles, “The Large Angle Spectroscopic Coronagraph (LASCO),” Solar Phys. 162, 1–2, 357–402 (1995).

Detwiler, C. R.

Evans, J. W.

Eyles, D. J.

G. E. Brueckner, R. A. Howard, M. J. Koomen, C. M. Korendyke, D. J. Michels, D. G. Socker, K. P. Dere, P. L. Lamy, A. Llebaria, M.-V. Bout, R. Schwenn, G. M. Simnett, D. K. Bedford, D. J. Eyles, “The Large Angle Spectroscopic Coronagraph (LASCO),” Solar Phys. 162, 1–2, 357–402 (1995).

Forel, C.

B. Fort, C. Forel, G. Spaak, “The reduction of scattered light in an external occulting disk coronagraph,” Astron. Astrophys. 63, 243–246 (1978).

Fort, B.

B. Fort, C. Forel, G. Spaak, “The reduction of scattered light in an external occulting disk coronagraph,” Astron. Astrophys. 63, 243–246 (1978).

Gosling, J. T.

R. M. MacQueen, J. T. Gosling, E. Hildner, R. H. Munro, A. I. Poland, C. L. Ross, “The High Altitude Observatory white light coronagraph,” in Instrumentation in Astronomy II, D. H. Menzel, L. Larmore, D. Crawford, eds., Proc. SPIE44, 207–212 (1974).
[CrossRef]

Hildner, E.

R. M. MacQueen, A. Csoeke-Poeckh, E. Hildner, L. House, R. Reynolds, A. Stanger, H. Tepoel, W. Wagner, “The High Altitude Observatory Coronagraph/Polarimeter on the Solar Maximum Mission,” Solar Phys. 65, 91–107 (1980).
[CrossRef]

R. M. MacQueen, J. T. Gosling, E. Hildner, R. H. Munro, A. I. Poland, C. L. Ross, “The High Altitude Observatory white light coronagraph,” in Instrumentation in Astronomy II, D. H. Menzel, L. Larmore, D. Crawford, eds., Proc. SPIE44, 207–212 (1974).
[CrossRef]

House, L.

R. M. MacQueen, A. Csoeke-Poeckh, E. Hildner, L. House, R. Reynolds, A. Stanger, H. Tepoel, W. Wagner, “The High Altitude Observatory Coronagraph/Polarimeter on the Solar Maximum Mission,” Solar Phys. 65, 91–107 (1980).
[CrossRef]

Howard, R. A.

G. E. Brueckner, R. A. Howard, M. J. Koomen, C. M. Korendyke, D. J. Michels, D. G. Socker, K. P. Dere, P. L. Lamy, A. Llebaria, M.-V. Bout, R. Schwenn, G. M. Simnett, D. K. Bedford, D. J. Eyles, “The Large Angle Spectroscopic Coronagraph (LASCO),” Solar Phys. 162, 1–2, 357–402 (1995).

N. R. Sheeley, D. J. Michels, R. A. Howard, M. J. Koomen, “Initial observations with the Solwind coronagraph,” Astrophys. J. 237, L99–L101 (1980).
[CrossRef]

Koomen, M. J.

G. E. Brueckner, R. A. Howard, M. J. Koomen, C. M. Korendyke, D. J. Michels, D. G. Socker, K. P. Dere, P. L. Lamy, A. Llebaria, M.-V. Bout, R. Schwenn, G. M. Simnett, D. K. Bedford, D. J. Eyles, “The Large Angle Spectroscopic Coronagraph (LASCO),” Solar Phys. 162, 1–2, 357–402 (1995).

N. R. Sheeley, D. J. Michels, R. A. Howard, M. J. Koomen, “Initial observations with the Solwind coronagraph,” Astrophys. J. 237, L99–L101 (1980).
[CrossRef]

M. J. Koomen, C. R. Detwiler, G. E. Brueckner, H. W. Cooper, T. Tousey, “White light coronagraph in OSO-7,” Appl. Opt. 14, 743–751 (1975).
[CrossRef] [PubMed]

J. D. Purcell, M. J. Koomen, “Coronagraph with improved scattered-light properties,” J. Opt. Soc. Am. 52, 596–597 (1962).

Korendyke, C. M.

G. E. Brueckner, R. A. Howard, M. J. Koomen, C. M. Korendyke, D. J. Michels, D. G. Socker, K. P. Dere, P. L. Lamy, A. Llebaria, M.-V. Bout, R. Schwenn, G. M. Simnett, D. K. Bedford, D. J. Eyles, “The Large Angle Spectroscopic Coronagraph (LASCO),” Solar Phys. 162, 1–2, 357–402 (1995).

Koutchmy, S.

S. Koutchmy, M. Belmahdi, “Improved measurements of scattered light levels behind occulting systems,” J. Opt. 18, 5–6, 265–269 (1987).

Lamy, P. L.

G. E. Brueckner, R. A. Howard, M. J. Koomen, C. M. Korendyke, D. J. Michels, D. G. Socker, K. P. Dere, P. L. Lamy, A. Llebaria, M.-V. Bout, R. Schwenn, G. M. Simnett, D. K. Bedford, D. J. Eyles, “The Large Angle Spectroscopic Coronagraph (LASCO),” Solar Phys. 162, 1–2, 357–402 (1995).

Lenskii, A. V.

A. V. Lenskii, “Theoretical assessment of efficiency of coronagraph external occulting systems,” Astron. Zh. 58, 648–659 (1981) [Sov. Astron. 25(3), 366–372 (1981)].

Llebaria, A.

G. E. Brueckner, R. A. Howard, M. J. Koomen, C. M. Korendyke, D. J. Michels, D. G. Socker, K. P. Dere, P. L. Lamy, A. Llebaria, M.-V. Bout, R. Schwenn, G. M. Simnett, D. K. Bedford, D. J. Eyles, “The Large Angle Spectroscopic Coronagraph (LASCO),” Solar Phys. 162, 1–2, 357–402 (1995).

MacQueen, R. M.

R. M. MacQueen, A. Csoeke-Poeckh, E. Hildner, L. House, R. Reynolds, A. Stanger, H. Tepoel, W. Wagner, “The High Altitude Observatory Coronagraph/Polarimeter on the Solar Maximum Mission,” Solar Phys. 65, 91–107 (1980).
[CrossRef]

R. M. MacQueen, J. T. Gosling, E. Hildner, R. H. Munro, A. I. Poland, C. L. Ross, “The High Altitude Observatory white light coronagraph,” in Instrumentation in Astronomy II, D. H. Menzel, L. Larmore, D. Crawford, eds., Proc. SPIE44, 207–212 (1974).
[CrossRef]

Michels, D. J.

G. E. Brueckner, R. A. Howard, M. J. Koomen, C. M. Korendyke, D. J. Michels, D. G. Socker, K. P. Dere, P. L. Lamy, A. Llebaria, M.-V. Bout, R. Schwenn, G. M. Simnett, D. K. Bedford, D. J. Eyles, “The Large Angle Spectroscopic Coronagraph (LASCO),” Solar Phys. 162, 1–2, 357–402 (1995).

N. R. Sheeley, D. J. Michels, R. A. Howard, M. J. Koomen, “Initial observations with the Solwind coronagraph,” Astrophys. J. 237, L99–L101 (1980).
[CrossRef]

Munro, R. H.

R. M. MacQueen, J. T. Gosling, E. Hildner, R. H. Munro, A. I. Poland, C. L. Ross, “The High Altitude Observatory white light coronagraph,” in Instrumentation in Astronomy II, D. H. Menzel, L. Larmore, D. Crawford, eds., Proc. SPIE44, 207–212 (1974).
[CrossRef]

Newkirk, G.

Poland, A. I.

R. M. MacQueen, J. T. Gosling, E. Hildner, R. H. Munro, A. I. Poland, C. L. Ross, “The High Altitude Observatory white light coronagraph,” in Instrumentation in Astronomy II, D. H. Menzel, L. Larmore, D. Crawford, eds., Proc. SPIE44, 207–212 (1974).
[CrossRef]

Purcell, J. D.

J. D. Purcell, M. J. Koomen, “Coronagraph with improved scattered-light properties,” J. Opt. Soc. Am. 52, 596–597 (1962).

Reynolds, R.

R. M. MacQueen, A. Csoeke-Poeckh, E. Hildner, L. House, R. Reynolds, A. Stanger, H. Tepoel, W. Wagner, “The High Altitude Observatory Coronagraph/Polarimeter on the Solar Maximum Mission,” Solar Phys. 65, 91–107 (1980).
[CrossRef]

Ross, C. L.

R. M. MacQueen, J. T. Gosling, E. Hildner, R. H. Munro, A. I. Poland, C. L. Ross, “The High Altitude Observatory white light coronagraph,” in Instrumentation in Astronomy II, D. H. Menzel, L. Larmore, D. Crawford, eds., Proc. SPIE44, 207–212 (1974).
[CrossRef]

Schwenn, R.

G. E. Brueckner, R. A. Howard, M. J. Koomen, C. M. Korendyke, D. J. Michels, D. G. Socker, K. P. Dere, P. L. Lamy, A. Llebaria, M.-V. Bout, R. Schwenn, G. M. Simnett, D. K. Bedford, D. J. Eyles, “The Large Angle Spectroscopic Coronagraph (LASCO),” Solar Phys. 162, 1–2, 357–402 (1995).

Sheeley, N. R.

N. R. Sheeley, D. J. Michels, R. A. Howard, M. J. Koomen, “Initial observations with the Solwind coronagraph,” Astrophys. J. 237, L99–L101 (1980).
[CrossRef]

Simnett, G. M.

G. E. Brueckner, R. A. Howard, M. J. Koomen, C. M. Korendyke, D. J. Michels, D. G. Socker, K. P. Dere, P. L. Lamy, A. Llebaria, M.-V. Bout, R. Schwenn, G. M. Simnett, D. K. Bedford, D. J. Eyles, “The Large Angle Spectroscopic Coronagraph (LASCO),” Solar Phys. 162, 1–2, 357–402 (1995).

Socker, D. G.

G. E. Brueckner, R. A. Howard, M. J. Koomen, C. M. Korendyke, D. J. Michels, D. G. Socker, K. P. Dere, P. L. Lamy, A. Llebaria, M.-V. Bout, R. Schwenn, G. M. Simnett, D. K. Bedford, D. J. Eyles, “The Large Angle Spectroscopic Coronagraph (LASCO),” Solar Phys. 162, 1–2, 357–402 (1995).

Spaak, G.

B. Fort, C. Forel, G. Spaak, “The reduction of scattered light in an external occulting disk coronagraph,” Astron. Astrophys. 63, 243–246 (1978).

Stanger, A.

R. M. MacQueen, A. Csoeke-Poeckh, E. Hildner, L. House, R. Reynolds, A. Stanger, H. Tepoel, W. Wagner, “The High Altitude Observatory Coronagraph/Polarimeter on the Solar Maximum Mission,” Solar Phys. 65, 91–107 (1980).
[CrossRef]

Tepoel, H.

R. M. MacQueen, A. Csoeke-Poeckh, E. Hildner, L. House, R. Reynolds, A. Stanger, H. Tepoel, W. Wagner, “The High Altitude Observatory Coronagraph/Polarimeter on the Solar Maximum Mission,” Solar Phys. 65, 91–107 (1980).
[CrossRef]

Tousey, T.

Wagner, W.

R. M. MacQueen, A. Csoeke-Poeckh, E. Hildner, L. House, R. Reynolds, A. Stanger, H. Tepoel, W. Wagner, “The High Altitude Observatory Coronagraph/Polarimeter on the Solar Maximum Mission,” Solar Phys. 65, 91–107 (1980).
[CrossRef]

Appl. Opt. (2)

Astron. Astrophys. (1)

B. Fort, C. Forel, G. Spaak, “The reduction of scattered light in an external occulting disk coronagraph,” Astron. Astrophys. 63, 243–246 (1978).

Astron. Zh. (1)

A. V. Lenskii, “Theoretical assessment of efficiency of coronagraph external occulting systems,” Astron. Zh. 58, 648–659 (1981) [Sov. Astron. 25(3), 366–372 (1981)].

Astrophys. J. (1)

N. R. Sheeley, D. J. Michels, R. A. Howard, M. J. Koomen, “Initial observations with the Solwind coronagraph,” Astrophys. J. 237, L99–L101 (1980).
[CrossRef]

J. Opt. (1)

S. Koutchmy, M. Belmahdi, “Improved measurements of scattered light levels behind occulting systems,” J. Opt. 18, 5–6, 265–269 (1987).

J. Opt. Soc. Am. (2)

J. D. Purcell, M. J. Koomen, “Coronagraph with improved scattered-light properties,” J. Opt. Soc. Am. 52, 596–597 (1962).

J. W. Evans, “A photometer for measurement of sky brightness near the Sun,” J. Opt. Soc. Am. 38, 1083–1085 (1948).
[CrossRef] [PubMed]

Solar Phys. (2)

R. M. MacQueen, A. Csoeke-Poeckh, E. Hildner, L. House, R. Reynolds, A. Stanger, H. Tepoel, W. Wagner, “The High Altitude Observatory Coronagraph/Polarimeter on the Solar Maximum Mission,” Solar Phys. 65, 91–107 (1980).
[CrossRef]

G. E. Brueckner, R. A. Howard, M. J. Koomen, C. M. Korendyke, D. J. Michels, D. G. Socker, K. P. Dere, P. L. Lamy, A. Llebaria, M.-V. Bout, R. Schwenn, G. M. Simnett, D. K. Bedford, D. J. Eyles, “The Large Angle Spectroscopic Coronagraph (LASCO),” Solar Phys. 162, 1–2, 357–402 (1995).

Other (2)

R. M. MacQueen, J. T. Gosling, E. Hildner, R. H. Munro, A. I. Poland, C. L. Ross, “The High Altitude Observatory white light coronagraph,” in Instrumentation in Astronomy II, D. H. Menzel, L. Larmore, D. Crawford, eds., Proc. SPIE44, 207–212 (1974).
[CrossRef]

D. Bohlin, NASA Headquarters, 300 E Street, SW, Washington, D.C. (personal communication, 15October1989).

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Figures (12)

Fig. 1
Fig. 1

Schematic diagrams of the EO’s: (a) single disk, (b) triple disk, (c) polished cone, (d) multithreaded cone. The cones are hollow, as is indicated by the dashed lines.

Fig. 2
Fig. 2

Design of the serrated diaphragm.

Fig. 3
Fig. 3

Optical principles of the solar simulator, the OSO, that was used to test the LASCO-C2 EO and entrance diaphragm AO.

Fig. 4
Fig. 4

Irradiance map produced by the solar simulator in the aperture plane of the instrument over a square region that measured 90 mm × 90 mm. The irradiance is normalized to the maximum value of B O and displayed in accord with the gray scale on the right-hand side.

Fig. 5
Fig. 5

Illustrations of the methods of the measurements: (a) measurement of the scattered light L A1, (b) measurement of the efficiency of T R , (c) imaging of the fringe of the EO.

Fig. 6
Fig. 6

Images of the diffraction fringe: From the image plane to point A the image appears as a bright ring of light with a dark center, F. At point A it is a bright circular spot of light that is measured by the photometer. Beyond point A the image appears as a circular spot with a bright center, B.

Fig. 7
Fig. 7

Variation of the efficiency T R plotted versus the angular offset δα.

Fig. 8
Fig. 8

Variation of the efficiency T R plotted versus the lateral offset δx.

Fig. 9
Fig. 9

Calibrated image of the radiance of the fringe of EO S5. The logarithm of the radiance (expressed in units of B/B O ) ranges from -8 to -5, in accord with the gray scale on the right-hand side.

Fig. 10
Fig. 10

Calibrated mean radial profiles of the image of the fringe of EO S5 as measured in the laboratory without (dotted curve) and with (dashed curve) stray-light correction and as measured in-flight (solid curve). The direction to the center of the EO is indicated.

Fig. 11
Fig. 11

Calibrated image of the radiance of the actual fringe of the EO of the LASCO-C2 coronagraph aboard SOHO at the L2 Lagrangian point. The logarithm of the radiance (expressed in units of B/B O ) ranges from -9 to -5, in accord with the gray scale on the right-hand side.

Fig. 12
Fig. 12

Calibrated mosaic image of the radiance of the diffraction pattern of the serrated diaphragm. The logarithm of the radiance (expressed in units of B/B O ) ranges from -8 to -5, in accord with the gray scale on the right-hand side.

Tables (1)

Tables Icon

Table 1 Characteristics and Performance of the EO Systems

Equations (3)

Equations on this page are rendered with MathJax. Learn more.

LA1=π2R1-RDr2-1λr,
g=2r2πa2α0Rψ0-ψa2,
ψy=cosh-11+r-RD2-y22rRD.

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