Abstract

The results of a project to develop a spatial heterodyne spectrometer (SHS) for a sounding rocket mission to study the Cygnus Loop, a prototypical middle-aged supernova remnant, are discussed. The goal was to obtain a radial velocity-resolved spectrum of the C IV λλ1550 emission line from bright features of the Cygnus Loop, as a test for mapping the diffuse hot interstellar medium (ISM). A full Fourier-transform analysis of Cygnus Loop emission data is presented, showing lack of velocity-resolved C IV emission detection. Optics contamination is shown to be the most likely problem, and ways to eliminate this contamination for future SHS sounding rocket and satellite missions are discussed.

© 2010 Optical Society of America

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References

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  1. J. Harlander, R. J. Reynolds, and F. L. Roesler, “Spatial heterodyne spectroscopy for the exploration of diffuse interstellar emission lines at far-ultraviolet wavelengths,” Astrophys. J. 396, 730–740 (1992).
    [CrossRef]
  2. J. Harlander, F. L. Roesler, R. J. Reynolds, K. Jaehnig, and W. Sanders, “A differential field-widened spatial heterodyne spectrometer for investigations at high spectral resolution of the diffuse far-ultraviolet 1548Å emission line from the interstellar medium,” Proc. SPIE 2006, 139–148(1993).
    [CrossRef]
  3. S. Watchorn, F. L. Roesler, J. Harlander, K. P. Jaehnig, R. J. Reynolds, and W. T. Sanders, “Development of the spatial heterodyne spectrometer for VUV remote sensing of the interstellar medium,” Proc. SPIE 4498, 284–295 (2001).
    [CrossRef]
  4. S. Watchorn, “The development of the spatial heterodyne spectrometer for observations of C IV emissions near 1550Å from the Cygnus Loop and the diffuse hot interstellar medium,” Ph.D. dissertation (University of Wisconsin, 2001).
  5. J. Harlander, H. T. Tran, F. L. Roesler, K. P. Jaehnig, S. M. Seo, W. T. Sanders, and R. J. Reynolds, “Field-widened spatial heterodyne spectroscopy: correcting for optical defects and new ultraviolet vacuum performance tests,” Proc. SPIE 2280, 310–319 (1994).
    [CrossRef]
  6. C. Martin and S. Bowyer, “Discovery of high-ionization far-ultraviolet line emission from the interstellar medium,” Astrophys. J. 350, 242–261 (1990).
    [CrossRef]
  7. K-I. Seon, W. Han, U.-W. Nam, J.-H. Park, J. Edelstein, E. J. Korpela, R. Sankrit, K.-W. Min, K. Ryu, and I.-J. Kim, “Far-ultraviolet spectral images of the Cygnus Loop,” Astrophys. J. 644, L175–L179 (2006).
    [CrossRef]
  8. O. R. Dawson and W. M. Harris, “Tunable, all-reflective spatial heterodyne spectrometer for broadband spectral line studies in the visible and near-ultraviolet,” Appl. Opt. 48, 4227–4238 (2009).
    [CrossRef] [PubMed]

2009 (1)

2006 (1)

K-I. Seon, W. Han, U.-W. Nam, J.-H. Park, J. Edelstein, E. J. Korpela, R. Sankrit, K.-W. Min, K. Ryu, and I.-J. Kim, “Far-ultraviolet spectral images of the Cygnus Loop,” Astrophys. J. 644, L175–L179 (2006).
[CrossRef]

2001 (1)

S. Watchorn, F. L. Roesler, J. Harlander, K. P. Jaehnig, R. J. Reynolds, and W. T. Sanders, “Development of the spatial heterodyne spectrometer for VUV remote sensing of the interstellar medium,” Proc. SPIE 4498, 284–295 (2001).
[CrossRef]

1994 (1)

J. Harlander, H. T. Tran, F. L. Roesler, K. P. Jaehnig, S. M. Seo, W. T. Sanders, and R. J. Reynolds, “Field-widened spatial heterodyne spectroscopy: correcting for optical defects and new ultraviolet vacuum performance tests,” Proc. SPIE 2280, 310–319 (1994).
[CrossRef]

1993 (1)

J. Harlander, F. L. Roesler, R. J. Reynolds, K. Jaehnig, and W. Sanders, “A differential field-widened spatial heterodyne spectrometer for investigations at high spectral resolution of the diffuse far-ultraviolet 1548Å emission line from the interstellar medium,” Proc. SPIE 2006, 139–148(1993).
[CrossRef]

1992 (1)

J. Harlander, R. J. Reynolds, and F. L. Roesler, “Spatial heterodyne spectroscopy for the exploration of diffuse interstellar emission lines at far-ultraviolet wavelengths,” Astrophys. J. 396, 730–740 (1992).
[CrossRef]

1990 (1)

C. Martin and S. Bowyer, “Discovery of high-ionization far-ultraviolet line emission from the interstellar medium,” Astrophys. J. 350, 242–261 (1990).
[CrossRef]

Bowyer, S.

C. Martin and S. Bowyer, “Discovery of high-ionization far-ultraviolet line emission from the interstellar medium,” Astrophys. J. 350, 242–261 (1990).
[CrossRef]

Dawson, O. R.

Edelstein, J.

K-I. Seon, W. Han, U.-W. Nam, J.-H. Park, J. Edelstein, E. J. Korpela, R. Sankrit, K.-W. Min, K. Ryu, and I.-J. Kim, “Far-ultraviolet spectral images of the Cygnus Loop,” Astrophys. J. 644, L175–L179 (2006).
[CrossRef]

Han, W.

K-I. Seon, W. Han, U.-W. Nam, J.-H. Park, J. Edelstein, E. J. Korpela, R. Sankrit, K.-W. Min, K. Ryu, and I.-J. Kim, “Far-ultraviolet spectral images of the Cygnus Loop,” Astrophys. J. 644, L175–L179 (2006).
[CrossRef]

Harlander, J.

S. Watchorn, F. L. Roesler, J. Harlander, K. P. Jaehnig, R. J. Reynolds, and W. T. Sanders, “Development of the spatial heterodyne spectrometer for VUV remote sensing of the interstellar medium,” Proc. SPIE 4498, 284–295 (2001).
[CrossRef]

J. Harlander, H. T. Tran, F. L. Roesler, K. P. Jaehnig, S. M. Seo, W. T. Sanders, and R. J. Reynolds, “Field-widened spatial heterodyne spectroscopy: correcting for optical defects and new ultraviolet vacuum performance tests,” Proc. SPIE 2280, 310–319 (1994).
[CrossRef]

J. Harlander, F. L. Roesler, R. J. Reynolds, K. Jaehnig, and W. Sanders, “A differential field-widened spatial heterodyne spectrometer for investigations at high spectral resolution of the diffuse far-ultraviolet 1548Å emission line from the interstellar medium,” Proc. SPIE 2006, 139–148(1993).
[CrossRef]

J. Harlander, R. J. Reynolds, and F. L. Roesler, “Spatial heterodyne spectroscopy for the exploration of diffuse interstellar emission lines at far-ultraviolet wavelengths,” Astrophys. J. 396, 730–740 (1992).
[CrossRef]

Harris, W. M.

Jaehnig, K.

J. Harlander, F. L. Roesler, R. J. Reynolds, K. Jaehnig, and W. Sanders, “A differential field-widened spatial heterodyne spectrometer for investigations at high spectral resolution of the diffuse far-ultraviolet 1548Å emission line from the interstellar medium,” Proc. SPIE 2006, 139–148(1993).
[CrossRef]

Jaehnig, K. P.

S. Watchorn, F. L. Roesler, J. Harlander, K. P. Jaehnig, R. J. Reynolds, and W. T. Sanders, “Development of the spatial heterodyne spectrometer for VUV remote sensing of the interstellar medium,” Proc. SPIE 4498, 284–295 (2001).
[CrossRef]

J. Harlander, H. T. Tran, F. L. Roesler, K. P. Jaehnig, S. M. Seo, W. T. Sanders, and R. J. Reynolds, “Field-widened spatial heterodyne spectroscopy: correcting for optical defects and new ultraviolet vacuum performance tests,” Proc. SPIE 2280, 310–319 (1994).
[CrossRef]

Kim, I.-J.

K-I. Seon, W. Han, U.-W. Nam, J.-H. Park, J. Edelstein, E. J. Korpela, R. Sankrit, K.-W. Min, K. Ryu, and I.-J. Kim, “Far-ultraviolet spectral images of the Cygnus Loop,” Astrophys. J. 644, L175–L179 (2006).
[CrossRef]

Korpela, E. J.

K-I. Seon, W. Han, U.-W. Nam, J.-H. Park, J. Edelstein, E. J. Korpela, R. Sankrit, K.-W. Min, K. Ryu, and I.-J. Kim, “Far-ultraviolet spectral images of the Cygnus Loop,” Astrophys. J. 644, L175–L179 (2006).
[CrossRef]

Martin, C.

C. Martin and S. Bowyer, “Discovery of high-ionization far-ultraviolet line emission from the interstellar medium,” Astrophys. J. 350, 242–261 (1990).
[CrossRef]

Min, K.-W.

K-I. Seon, W. Han, U.-W. Nam, J.-H. Park, J. Edelstein, E. J. Korpela, R. Sankrit, K.-W. Min, K. Ryu, and I.-J. Kim, “Far-ultraviolet spectral images of the Cygnus Loop,” Astrophys. J. 644, L175–L179 (2006).
[CrossRef]

Nam, U.-W.

K-I. Seon, W. Han, U.-W. Nam, J.-H. Park, J. Edelstein, E. J. Korpela, R. Sankrit, K.-W. Min, K. Ryu, and I.-J. Kim, “Far-ultraviolet spectral images of the Cygnus Loop,” Astrophys. J. 644, L175–L179 (2006).
[CrossRef]

Park, J.-H.

K-I. Seon, W. Han, U.-W. Nam, J.-H. Park, J. Edelstein, E. J. Korpela, R. Sankrit, K.-W. Min, K. Ryu, and I.-J. Kim, “Far-ultraviolet spectral images of the Cygnus Loop,” Astrophys. J. 644, L175–L179 (2006).
[CrossRef]

Reynolds, R. J.

S. Watchorn, F. L. Roesler, J. Harlander, K. P. Jaehnig, R. J. Reynolds, and W. T. Sanders, “Development of the spatial heterodyne spectrometer for VUV remote sensing of the interstellar medium,” Proc. SPIE 4498, 284–295 (2001).
[CrossRef]

J. Harlander, H. T. Tran, F. L. Roesler, K. P. Jaehnig, S. M. Seo, W. T. Sanders, and R. J. Reynolds, “Field-widened spatial heterodyne spectroscopy: correcting for optical defects and new ultraviolet vacuum performance tests,” Proc. SPIE 2280, 310–319 (1994).
[CrossRef]

J. Harlander, F. L. Roesler, R. J. Reynolds, K. Jaehnig, and W. Sanders, “A differential field-widened spatial heterodyne spectrometer for investigations at high spectral resolution of the diffuse far-ultraviolet 1548Å emission line from the interstellar medium,” Proc. SPIE 2006, 139–148(1993).
[CrossRef]

J. Harlander, R. J. Reynolds, and F. L. Roesler, “Spatial heterodyne spectroscopy for the exploration of diffuse interstellar emission lines at far-ultraviolet wavelengths,” Astrophys. J. 396, 730–740 (1992).
[CrossRef]

Roesler, F. L.

S. Watchorn, F. L. Roesler, J. Harlander, K. P. Jaehnig, R. J. Reynolds, and W. T. Sanders, “Development of the spatial heterodyne spectrometer for VUV remote sensing of the interstellar medium,” Proc. SPIE 4498, 284–295 (2001).
[CrossRef]

J. Harlander, H. T. Tran, F. L. Roesler, K. P. Jaehnig, S. M. Seo, W. T. Sanders, and R. J. Reynolds, “Field-widened spatial heterodyne spectroscopy: correcting for optical defects and new ultraviolet vacuum performance tests,” Proc. SPIE 2280, 310–319 (1994).
[CrossRef]

J. Harlander, F. L. Roesler, R. J. Reynolds, K. Jaehnig, and W. Sanders, “A differential field-widened spatial heterodyne spectrometer for investigations at high spectral resolution of the diffuse far-ultraviolet 1548Å emission line from the interstellar medium,” Proc. SPIE 2006, 139–148(1993).
[CrossRef]

J. Harlander, R. J. Reynolds, and F. L. Roesler, “Spatial heterodyne spectroscopy for the exploration of diffuse interstellar emission lines at far-ultraviolet wavelengths,” Astrophys. J. 396, 730–740 (1992).
[CrossRef]

Ryu, K.

K-I. Seon, W. Han, U.-W. Nam, J.-H. Park, J. Edelstein, E. J. Korpela, R. Sankrit, K.-W. Min, K. Ryu, and I.-J. Kim, “Far-ultraviolet spectral images of the Cygnus Loop,” Astrophys. J. 644, L175–L179 (2006).
[CrossRef]

Sanders, W.

J. Harlander, F. L. Roesler, R. J. Reynolds, K. Jaehnig, and W. Sanders, “A differential field-widened spatial heterodyne spectrometer for investigations at high spectral resolution of the diffuse far-ultraviolet 1548Å emission line from the interstellar medium,” Proc. SPIE 2006, 139–148(1993).
[CrossRef]

Sanders, W. T.

S. Watchorn, F. L. Roesler, J. Harlander, K. P. Jaehnig, R. J. Reynolds, and W. T. Sanders, “Development of the spatial heterodyne spectrometer for VUV remote sensing of the interstellar medium,” Proc. SPIE 4498, 284–295 (2001).
[CrossRef]

J. Harlander, H. T. Tran, F. L. Roesler, K. P. Jaehnig, S. M. Seo, W. T. Sanders, and R. J. Reynolds, “Field-widened spatial heterodyne spectroscopy: correcting for optical defects and new ultraviolet vacuum performance tests,” Proc. SPIE 2280, 310–319 (1994).
[CrossRef]

Sankrit, R.

K-I. Seon, W. Han, U.-W. Nam, J.-H. Park, J. Edelstein, E. J. Korpela, R. Sankrit, K.-W. Min, K. Ryu, and I.-J. Kim, “Far-ultraviolet spectral images of the Cygnus Loop,” Astrophys. J. 644, L175–L179 (2006).
[CrossRef]

Seo, S. M.

J. Harlander, H. T. Tran, F. L. Roesler, K. P. Jaehnig, S. M. Seo, W. T. Sanders, and R. J. Reynolds, “Field-widened spatial heterodyne spectroscopy: correcting for optical defects and new ultraviolet vacuum performance tests,” Proc. SPIE 2280, 310–319 (1994).
[CrossRef]

Seon, K-I.

K-I. Seon, W. Han, U.-W. Nam, J.-H. Park, J. Edelstein, E. J. Korpela, R. Sankrit, K.-W. Min, K. Ryu, and I.-J. Kim, “Far-ultraviolet spectral images of the Cygnus Loop,” Astrophys. J. 644, L175–L179 (2006).
[CrossRef]

Tran, H. T.

J. Harlander, H. T. Tran, F. L. Roesler, K. P. Jaehnig, S. M. Seo, W. T. Sanders, and R. J. Reynolds, “Field-widened spatial heterodyne spectroscopy: correcting for optical defects and new ultraviolet vacuum performance tests,” Proc. SPIE 2280, 310–319 (1994).
[CrossRef]

Watchorn, S.

S. Watchorn, F. L. Roesler, J. Harlander, K. P. Jaehnig, R. J. Reynolds, and W. T. Sanders, “Development of the spatial heterodyne spectrometer for VUV remote sensing of the interstellar medium,” Proc. SPIE 4498, 284–295 (2001).
[CrossRef]

S. Watchorn, “The development of the spatial heterodyne spectrometer for observations of C IV emissions near 1550Å from the Cygnus Loop and the diffuse hot interstellar medium,” Ph.D. dissertation (University of Wisconsin, 2001).

Appl. Opt. (1)

Astrophys. J. (3)

C. Martin and S. Bowyer, “Discovery of high-ionization far-ultraviolet line emission from the interstellar medium,” Astrophys. J. 350, 242–261 (1990).
[CrossRef]

K-I. Seon, W. Han, U.-W. Nam, J.-H. Park, J. Edelstein, E. J. Korpela, R. Sankrit, K.-W. Min, K. Ryu, and I.-J. Kim, “Far-ultraviolet spectral images of the Cygnus Loop,” Astrophys. J. 644, L175–L179 (2006).
[CrossRef]

J. Harlander, R. J. Reynolds, and F. L. Roesler, “Spatial heterodyne spectroscopy for the exploration of diffuse interstellar emission lines at far-ultraviolet wavelengths,” Astrophys. J. 396, 730–740 (1992).
[CrossRef]

Proc. SPIE (3)

J. Harlander, F. L. Roesler, R. J. Reynolds, K. Jaehnig, and W. Sanders, “A differential field-widened spatial heterodyne spectrometer for investigations at high spectral resolution of the diffuse far-ultraviolet 1548Å emission line from the interstellar medium,” Proc. SPIE 2006, 139–148(1993).
[CrossRef]

S. Watchorn, F. L. Roesler, J. Harlander, K. P. Jaehnig, R. J. Reynolds, and W. T. Sanders, “Development of the spatial heterodyne spectrometer for VUV remote sensing of the interstellar medium,” Proc. SPIE 4498, 284–295 (2001).
[CrossRef]

J. Harlander, H. T. Tran, F. L. Roesler, K. P. Jaehnig, S. M. Seo, W. T. Sanders, and R. J. Reynolds, “Field-widened spatial heterodyne spectroscopy: correcting for optical defects and new ultraviolet vacuum performance tests,” Proc. SPIE 2280, 310–319 (1994).
[CrossRef]

Other (1)

S. Watchorn, “The development of the spatial heterodyne spectrometer for observations of C IV emissions near 1550Å from the Cygnus Loop and the diffuse hot interstellar medium,” Ph.D. dissertation (University of Wisconsin, 2001).

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Figures (8)

Fig. 1
Fig. 1

Schematic layout of the basic spatial heterodyne spectrometer. Light is collimated into the spectrometer, and cross-diffracted by the optically crossed gratings. The important path difference for interference is between the crossed wavefronts. The output optics images the fringes from the plane of localization at the gratings to the pixelated detector for analysis. This action is shown by the dotted lines originating at the grating and running to the detector (as opposed to the dashed lines which go through the entire system).

Fig. 2
Fig. 2

Full-grating fringe image created by the phosphorus I line ( 1536 Å ) from the calibration lamp in the SHS payload, recorded on the flight detector. The semicircular shadows intruding into the grating image are caused by the “feet” that clamp the gratings to their holders.

Fig. 3
Fig. 3

Schematic layout for field-widened SHS. Wedge prisms are inserted in each arm, altering the relationship between the input and output angles of light so that the spatial frequency of the fringe pattern changes more slowly with an off-axis angle. A wider angle may thus be accommodated before the self-apodization limit is reached. As with other components, the wedge prisms do not have to be moved or scanned once installed and aligned.

Fig. 4
Fig. 4

Schematic of the differential, field-widened imaging spatial heterodyne spectrometer (ISHS) (cf. Fig. 3). Curved wavefronts are shown on the output side (off axis and exaggerated, for clarity). An image of the target is brought to the gratings and imaged (with the fringes) to the detector by the output optics, shown in a schematic configuration. Two-dimensional imaging requires the target to be scanned spatially in one dimension across the gratings, with time tagging, to construct the full fringe pattern (shown by the light/dark regions at the output lens image plane) and to get full spectral resolving power for each point. The labeled arrows indicate the direction of one scan in time.

Fig. 5
Fig. 5

Layout for the VUV SHS payload. The primary telescope matches the acceptance angle of the interferometer to 2.25 ° × 2.25 ° of the angular extent of the Cygnus Loop target. The wedge refractor rotates the image of the sky onto the tilted gratings with minimum distortion. The three filter mirrors on the output side increase out-of-band rejection. The toric lens and the lens combination directly in front of the CsI detector are the output optics schematized in Fig. 1.

Fig. 6
Fig. 6

Conceptual figure for the effect of pointing drift on imaging the VUV SHS fringes. The fringes “ride” with the instrument and are illuminated as bright features of the Cygnus Loop fill the instrument from angles corresponding to those fringes. As the scanning drifts off target from (a) to (b), only the angle corresponding to the fringes on “top” of the instrument are filled; eventually, in the last scan (c), none of them are filled, once the payload has drifted off target. Without reduced efficiency, however, the fringes should still be visible, since the majority of scans had at least some bright filaments in them to illuminate fringes on the upper part of the grating.

Fig. 7
Fig. 7

Detector image from the Cygnus Loop. Hot spots at the level of 5 counts or more have been median-corrected. No fringes are visible (cf. Fig. 3), and no spectral features are apparent in the Fourier transform of the grating region (which can be determined by comparison with the image in Fig. 3).

Fig. 8
Fig. 8

Fourier transform of the pointing-drift-corrected Cygnus Loop image for the (a) 1548 Å and (b) 1550 Å line of the C IV doublet. The intensity (vertical) axis and wavelength (horizontal) axis are both labeled with arbitrary units. The dashed lines mark the region in which the spectral lines in each case should appear, based on instrument parameters at the time of observation. No spectral peaks are evident above the noise, another indication of the lack of spectroscopic detection of the Cygnus Loop C IV emissions.

Tables (2)

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Table 1 Cygnus Loop VUV SHS Spectroscopic Parameters

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Table 2 Expected and Measured Efficiencies for Payload and Significant Components

Equations (2)

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I ( x ) = 0 B ( σ ) [ 1 + cos ( 8 π x ( tan θ 1 tan θ 2 ) ( σ σ 0 ) ) ] d σ ,
s n = S 2 ε A Ω t f ( S + B Δ λ ) ,

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