Segmented mirror coarse phasing with a dispersed fringe sensor: experiments on NGST's Wavefront Control Testbed

Redding, David C.; Lowman, Andrew E.; Bowers, Charles W.; Burns, Laura A.; Petrone, Peter; Ohara, Catherine M.; Basinger, Scott A.

doi:10.1117/12.461113

Cited by 30 publications

(19 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The orientation of the grating is also critical when phasing segments with the DFS. Maximum fringe contrast occurs when the dispersion direction is perpendicular the baseline between segment pairs [7].…”

Section: Coarse Phasing Pma With Dispersed Fringe Sensor (Dfs)mentioning

confidence: 99%

See 1 more Smart Citation

Fabrication and characterization of the Fizeau interferometer testbed

Petrone

Carpenter

Clark

et al. 2004

New Frontiers in Stellar Interferometry

Self Cite

View full text Add to dashboard Cite

The Fizeau Interferometer Testbed (FIT) is a ground-based system that will be used for the development and testing of technologies relevant to Stellar Imager (SI) and other sparse aperture/Fizeau imaging interferometer mission concepts. The testbed will utilize image-based wavefront sensing and control to co-phase and maintain closed-loop control over a Sparse Aperture Array (SAA) consisting of spherical mirror elements. The SAA is a re-configurable assembly baselined to incorporate between seven (initially) and thirty 12.5mm diameter (R = 4000mm) mirror elements. In this paper we describe the fabrication, alignment, and initial calibration of the phase I (7 primary elements) FIT hardware and discuss various factors impacting the performance and stability of the testbed.

show abstract

Section: Coarse Phasing Pma With Dispersed Fringe Sensor (Dfs)mentioning

confidence: 99%

“…The FIT Primary Mirror Array (PMA) plate employs (7) spherical mirror segments (f = 2000mm) configured in a minimum-redundancy pattern [2,3]. Each mirror segment has five degrees of freedom (tip, tilt, piston and X-Y decenter).…”

Section: Introductionmentioning

confidence: 99%

Fabrication and characterization of the Fizeau interferometer testbed

Petrone

Carpenter

Clark

et al. 2004

New Frontiers in Stellar Interferometry

Self Cite

View full text Add to dashboard Cite

show abstract

“…6 The DFS consists of a grism on a flip-in mechanism. A white light source will be used in this mode.…”

Section: Sensor Modulementioning

confidence: 99%

Phase retrieval camera for testing NGST optics

et al. 2003

Self Cite

View full text Add to dashboard Cite

The NGST Phase Retrieval Camera (PRC) is a portable wavefront sensor useful for optical testing in high-vibration environments. The PRC uses focus-diverse phase retrieval to measure the wavefront propagating from the optical component or system under test. Phase retrieval from focal plane images is less sensitive to jitter than standard pupil plane interferometric measurements; the PRC's performance is further enhanced by using a high-speed shutter to freeze out seeing and jitter along with a reference camera to maintain the correct boresight in defocused images. The PRC hardware was developed using components similar to those in NGST's Wavefront Control Testbed (WCT), while the PRC software was derived from WCT's extensive software infrastructure. Primary applications of the PRC are testing and experimenting with NGST technology demonstrator mirrors, along with exploring other wavefront sensing and control problems not easily studied using WCT. An overview of the hardware and testing results will be presented.

show abstract

“…On the JWST Wavefront Control Testbed (WCT), we demonstrated closed-loop DFS performance with an accuracy of 50 nm and a capture range of 100 µm [4,5] . The DFS algorithm also performs well in computer simulations of the JWST 18-hexagon design, the Developmental Comparative Active Telescope Testbed (DCATT), and the double-pass JWST optical testing system at Plum Brook.…”

Section: Introductionmentioning

confidence: 97%

Experimental verification of dispersed fringe sensing as a segment-phasing technique using the Keck Telescope

Ohara¹,

Chanan²,

Troy³

et al. 2004

SPIE Proceedings

Self Cite

View full text Add to dashboard Cite

Dispersed Fringe Sensing (DFS) is an efficient and robust method for coarse phasing of segmented primary mirrors (from a quarter of a wavelength up to the depth of focus of a single segment, typically several tens of microns). Unlike phasing techniques currently used for ground-based segmented telescopes, DFS does not require the use of edge sensors to sense changes in the relative heights of adjacent segments; this makes it particularly well-suited to the phasing of space-borne segmented telescopes, such as the James Webb Space Telescope (JWST). In this work we validate DFS by using it to measure the pistons of the segments of one of the Keck telescopes; the results agree with those of the ShackHartmann based phasing scheme currently in use at Keck to within 2% over a range of initial piston errors of ±16 µm.

show abstract

Segmented mirror coarse phasing with a dispersed fringe sensor: experiments on NGST's Wavefront Control Testbed

Cited by 30 publications

References 4 publications

Fabrication and characterization of the Fizeau interferometer testbed

Fabrication and characterization of the Fizeau interferometer testbed

Phase retrieval camera for testing NGST optics

Experimental verification of dispersed fringe sensing as a segment-phasing technique using the Keck Telescope

Contact Info

Product

Resources

About