PHARO (2?)

James Lloyd(Cornell)

PHARO is the Palomar Workhorse AO

Instrument•Commissioned in early 1998

•Built at Cornell: Tom Hayward/Bernhard Brandl

•JHK Imaging + spectroscopy + coronagraphy

•Very good optics

•All reflective: 2 plate scales

•25 mas (Nyquist @ 1.2 m)

•40 mas (Nyquist @ 1.9 m)

•35 nm RMS WFE (Hayward et al 2001)

Problems with PHARO

•Detector

•Early generation HAWAII-1 (1k)

•Very peculiar reset anomaly

•Limited dynamic range

•Reliability of acquisition system based on SPARC-2/SunOS platform

•Mechanism Reliability due to cryogenic Phytron Motors

Aperture Masking

Closure Phase/SelfCal

Contrast vs

L Band Masking @ Keck

L Band Masking @ Palomar

Upgrade PHARO?•Teledyne (Rockwell) has been

advertising the “H4-RG-10” as the next generation:

•4k x 4k detector with 10 micron pixels

•a 10 micron pixel would give PHARO Nyquist sampling at =660 nm.

•Current generation of HgCdTe detectors from Teledyne are available substrate removed with QE>70% to =400 nm

Upgrade PHARO?•This would be neat:

•push out to cover the visible for P3K and the L/M bands for a masking planet survey

•Solve the detector problems with PHARO

•Solve at the same time PHARO mechanical problems and implement additional desirable capabilities.

• (nb there is a wrinkle that additional cooling requires a new dewar)

•Cornell is considering an NSF/MRI proposal to fund this upgrade

Options1.10 micron pixel detector

• Teledyne has fabricated Si-pin H4RG-10, but there are problems with the unit cell

• A H4RG-10/H2RG-10 is probably $0.8M-$1.0M development today.

2.H2RG-18 with 0.7-5.3 m substrate removed detector: about $400k + a whole new instrument (at least another $1M)

3.H1RG-18 with 0.7-5.3 m substrate removal. May be able to add the optics for a finer plate scale, but likely will be stuck with 25mas pixels.

Questions/Comments?

•Will there be a role for PHARO without an upgrade?

•Are there other important considerations or suggestions for a PHARO upgrade?