OCAM2S: an integral shutter ultrafast and low noise wavefront sensor camera for laser guide stars adaptive optics systems

Gach, Jean-Luc; Feautrier, Philippe; Balard, Philippe; Guillaume, Christian; Stadler, Eric

doi:10.1117/12.2054264

Cited by 5 publications

(2 citation statements)

References 8 publications

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“…Although the SAPHIRA detector can be used in 0.8–2.5

\upmu

m wavelength range, this camera is designed to include four long‐wavelengths blocking filters that limit the sensitivity up to 1.75

\upmu

m. This step is taken to filter out the unwanted background flux outside the J and H‐band wavelength window, which would otherwise be amplified at low gain operation (Gach et al 2016).…”

Section: The C‐red One Cameramentioning

confidence: 99%

Characterization of a C‐RED One camera for astrophotonical applications

Vješnica,

Hernandez,

Madhav

et al. 2023

Astron Nachr

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To better understand the impact of the avalanche gain applied in the detector technology and apply this technology in our in‐house astrophotonic projects, we have characterized a C‐RED One camera and produced a stable and reliable method for calculating the system gain at any desired avalanche gain setting. We observed that depending on how the system gain is obtained, multiplying the system gain times the avalanche gain may not accurately produce a conversion factor from electrons to ADUs. As the acquisition of a photon transfer curve (PTC) was possible at different avalanche gain levels, several PTCs at low avalanche gain levels were acquired. Consequently, a linear fit was produced from the acquired system gain as a function of the avalanche gain setting. Through the linear fit, the effective system gain was calculated at any desired avalanche level. The effective system gain makes possible to accurately calculate the initial system gain without the ambiguity introduced by the nonlinearity of the system. Besides, the impact of the avalanche gain on the dynamic range was also analyzed and showed a stable behavior through the measured avalanche range.

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“…Although the SAPHIRA detector can be used in 0.8–2.5

\upmu

m wavelength range, this camera is designed to include four long‐wavelengths blocking filters that limit the sensitivity up to 1.75

\upmu

m. This step is taken to filter out the unwanted background flux outside the J and H‐band wavelength window, which would otherwise be amplified at low gain operation (Gach et al 2016).…”

Section: The C‐red One Cameramentioning

confidence: 99%

Characterization of a C‐RED One camera for astrophotonical applications

Vješnica,

Hernandez,

Madhav

et al. 2023

Astron Nachr

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“…The WFSs all have 7 × 7 sub-apertures, of which 36 are valid (not significantly vignetted). The LGS WFS has 30 × 30 pixels per sub-aperture, and is based on an electron multiplying CCD (EMCCD) detector with sub-electron readout noise (Gach et al 2016). It is equipped with a dedicated fast steering mirror to stabilize the LGS spots in the sub-apertures.…”

Section: Introductionmentioning

confidence: 99%

On-sky demonstration of matched filters for wavefront measurements using ELT-scale elongated laser guide stars

Basden

Bardou

Calia

et al. 2017

Mon. Not. R. Astron. Soc.

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The performance of adaptive optics systems is partially dependant on the algorithms used within the real-time control system to compute wavefront slope measurements. We demonstrate use of a matched filter algorithm for the processing of elongated laser guide star (LGS) Shack-Hartmann images, using the CANARY adaptive optics instrument on the 4.2 m William Herschel Telescope and the European Southern Observatory Wendelstein LGS Unit placed 40m away. This algorithm has been selected for use with the forthcoming Thirty Meter Telescope, but until now had not been demonstrated on-sky. From the results of a first observing run, we show that the use of matched filtering improves our adaptive optics system performance, with increases in on-sky H-band Strehl measured up to about a factor of 1.1 with respect to a conventional centre of gravity approach. We describe the algorithm used, and the methods that we implemented to enable on-sky demonstration.

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