CHAMP:Manual

Manual for the CHARA-Michigan Phasetracker*

• CHAMP*

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Hardware Subsystems

Dichroic Pickoffs

We have provided 3 sets of pickoff optics for use with CHAMP (the angle-of-incidence is 3 degrees). Each is designed with a 30' wedge and have been oriented with thick part down (i.e., transmitted beams is bent downward by 13.7', which may be relevant for downstream combiners during alignment procedure). All substrates have a broadband AR coating on the back-surface and the reflected light comes primarily from the front surface.

  * Short-wave Pass (SWP): 

These IR-grade Fused Silica substrates are coated with a dichroic coating to reflect K' band (2-2.3 microns) and to transmit JH bands (1.1-1.8 microns).

• Media:omega_swp.pdf: Performance of Shortwave Pass Dichroic (Omega)

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  * Long-wave Pass (LWP):

These Calcium Fluoride substrates are coated with a dichroic coating to reflect JH bands (1.1-1.8 microns) and to transmit K' band (2-2.3 microns and longer for possible future experiments).

• Media:lwp_performance_001.pdf: Performance of Longwave Pass Dichroic (Omega)

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  * Pickoffs Beam-splitters (BS):

These Calcium Fluoride beamsplitters were rejected from American Torch due to the coating not meeting specifications and the performance curves being proven unreliable. We believe the the coatings are about 50/50 at HK bands but are more like 75/25 (mostly transmitting) at J and beyond K band. This might prove useful in the future, but we do not expect these pickoff optics to be the best choice for most observers. Here is a measured transmission curve from the company, although we have not verified the accuracy yet:

• Media:Torch_BS_performance.pdf: Performance for (rejected) Beamsplitter Coatings (American Torch)

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Piezo Scanners

Piezojena 8micron Hardware card from National Instruments

Beamsplitters

The IR-grade Fused silica beamsplitters are 50% +/- 10% over the full JHK' bandpasses. The coatings were done by Omega Optical and you can find the coating performance here. The angle of incidence is ~11.5 degrees.

• Media:omega_bs.pdf: Beamsplitter Performance (Omega)

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Real-time system

Click here for detail on the upgrade to the realtime system RT_System

Appendices

Diagrams

targets filter box diagram filterwheel key

Spares

Optics

• Two (2) fused silica beam splitters for CHAMP combiner

• One (1) fused silica short-wave pass (SWP) dichroic pickoff

• One (1) calcium fluoride long-wave page (LWP) dichroic pickoff

• One (1) elliptical mirror mounted to invar piezo mount

• Four (4) f=450mm spherical mirrors for Tower of Power

• One (1) image slicer T1

• One (1) image slicer T2

• One (1) image slicer B1 [note: we are using the spare. the original B1 has some coating problems near apex and is put back as a backup/spare

• One (1) image slicer B2 [note: the backup spare B2 has slight problem where the bottom-right quad, B2d, is too large in one dimension. This means the pyramid will not fit in the holder. If one needs to use this backup, one will need to mill-out extra clearance in the holder]

Other things: TBDocumented, some card for camera electronics. zabar motors.

• One (1) motherboard for servers (compatible with mirkwood, champ -- one kept at CHARA, one at UM)

-- Main.monnier - 08 Feb 2009