CHAMP:Manual

Manual for the CHARA-Michigan Phasetracker*

• CHAMP*

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---+ Overview

---+ Quick Startup Guide

---+ Alignment ---++ Nightly Alignment ---++ Full Alignment

---+ Hardware Subsystems ---++ Overview ---++ 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)

%BR% ---++ Towers of Power ---++ Image Slicers ---++ CHAMP Dewar ---++ Filterset ---++ Triplet ---++ HAWAII-1 Detector

---+ Software ---++ Interface Computer (wolverine) ---+++ CHAMP control ---+++ Actuators ---++ Realtime Computer (champ) ---+++ Camera Readout ---+++ Piezo control ---+++ Delay line communication

---+ 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

Other things: TBDocumented, some card for camera electronics. zabar motors. image-slicing pyramids.

-- Main.monnier - 08 Feb 2009