1. SED Machine Col 1/2

    SED Machine Collimator 1/2 Doublet

    I sound like a repeating record. Marin Anderson [CIT] and I bonded SED machine doublet camera elements 3/4 today. The collimator is a 95-mm f/4 lens with a telectrinc input.

    Collimator 1/2

    Collimator 1/2

    Above is a stop motion video of the col 1/2 bonding performed by Marin Anderson and Nick Konidaris [Caltech]. The positive element is a CaF2 (ISP Optical), while the negative element is a fused silica (Heraeus suprasil). You'll note that there are several key elements in order of appearance: a checklist, blue tape, pink lens cleaner, kapton-tape shims applied with a tongue depressor, Sylgard-184 applied with pipettes, and q-tips for cleaning the lens.

    New Parts in Hand

    In addition to bonding, some parts have completed fabrication. So far we now have the lens barrels that hold the rainbow camera, collimator, and camera!

    The Rainbow Camera delrin barrel

    The rainbow camera barrel that contains a doublet, triplet, and singlet is shown. The barrel is made using delrin of a well-measured coefficient of thermal expansion, in order to control aberrations that appear at different temperatures.

    The collimator aluminum barrel

    The 95-mm f/4 collimator barrel is shown. The barrel sits in a V-block and is held down with springs (inspired by the OSMOS spectrograph). The barrel contains six elements, with most of the positive power produced by CaF2, and negative power and residual-aberration correction provided by Ohara Corporation i-line glasses. The mix of fragile materials and large expansion differences makes for some interesting mechanical engineering challenges.

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  2. SED Machine Cam 3/4 & Gemini Observatory Future

    SED Machine Camera 3/4 Doublet

    Marin Anderson [CIT] and I bonded SED machine doublet camera elements 3/4 today. The camera is a 125-mm f/5 Petzval-style lens made of Ohara PBL26Y (n 1.57 and Abbe 42.8) and Heraeus fused silica (n 1.46 and Abbe 68). Lens centration is expected to be better than 30 micron or so.

    Camera 3/4

    Camera 3/4 doublet - a success. Cam 3/4 was bonded on 14-Dec 2012.

    Gemini Capabilities

    Talk by Gemini director at Caltech.

    The Partnership 2013-2015

    Annual budget 2013: ~ 27 M ops + 4 M instrumentation

    Country Share Cost
    US 65.50  
    CA 18.65  
    BR 6.53  
    AU 6.21 ~ 1.7 M / yr
    AR 3.11  

    Gemini 2016-2018

    Australia is not sure about plans post 2015. The board will work to find potential new parties.

    The Observatory

    About 180 employees distributed over two sites. Not staffed to build own instruments. [Note: Keck has ~115 at one site].

    Random note: no naysmith platforms for Gemini which makes Highres spec hard. Five casegrin ports but two are used for AO + Calibration. Any given time there are three instruments.

    New instruments: GRACES [March/April first test], GHOS, Flamingos-2, and GPI. Dying: Michelle, T-ReCS

    GPI commissioning July 2013.

    How to Remain Competitive in the Next Decade?

    Future is ALMA, JWST, and how to profit most with these synergies?

    New opportunites in instrumentation. The observatory will build a complement of facility class instruments to cover broad parameter space. New instrument every 2-3 years and thus cycle through all instruments takes about 20 years.

    R&D is $100 K / year Upgrades $500 K / year

    Next strategic instrument (GIROS; xshooter). Requirements:

    • Workhorse
    • Science driven and include science cases. Synergies with LSST, JWST, ALMA, etc..
    • Wide bandwidth moderate-resolution spectrograph is the current best leading instrument by the committee's opinion.

    [QUESTION: Who are the forerunners?]

    React to a science case and deploy on a short schedule provide visitor instruments by the community. Gemini now wants to encourage visitor instruments.

    • Instrument is certified
    • Apply for time via TAC
    • Install and observe
    • Typical visit is 2 weeks. Instrument can be offered to community during two weeks.
    • Large programs to request campaigns.

    Two examples of visitor instruments

    DSSI: Speckle imaging. Got 20 mas resolution at 700 nm, offering instrument to community. PI (Howell, NASA AMES).

    TEXES returns to gemini. On IRTF since 2000. Operates between 4.5 and 25 µ with 0.5% spectral coverage at high (R~80 K) resolution with a 2" - 5" long slit. Team helps with proposals and data reudciton.

    The team must support: John Lacy [PI], Richter (UCDavis), Greathouse (Solar System), Jaffe (UT A).

    New Ways of Operating

    Large/long programs at Gemini. The board has agreed to place 20% of the time in a pool for large/long programs. Implementation is being worked out but starts in 2014A.

    Want high-impact science.

    Also are considering putting some ten of percent of time in monthly proposal deadlines. Many possible issues and potential problems being considered and explored: partner percentage, rejected proposals, how long to remain in queue? The advantage is you can win 12 months over the competition.


    • Some unique facility class instruments: GeMS, and GPI.
    • It's possible to bring your instrument to the telescope.
    • Chance to propose large, ground-breaking programs.
    • Unique flexibility in time domain for edge over competition.


    • Some interest in continuing to use MICHELLE in visiting mode.
    • Fast track queue idea is intriguing. If review urgency is an important criteria, then you must observe it quickly.
    • Noticed nothing in far IR (+mm). Cannot look beyond 20 µ from ground.
    • Visitor instruments comment. Keck SSC considered visitor instruments as valuable about ten years ago. Complaint of visitor instruments is that they are too costly to commission. Gemini has had good experiences (compared to Keck) and believes visitor instruments are a good future step.
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  3. SED Machine Bonding Woes

    As reported on 6 Dec the lens bond of camera 1/2 was a success. A little Sylgard-184 ended up on the lens girdle, but the lens is clear and beautiful. I stored the lens away in our humidity-controlled environment. I'm still trying to deal with the fact that some of my CaF2 elements are now coated on both sides (I wanted only a coating on one side).

    It turns out that an AR Coating tuned to operate on an air/glass interface performs about as well when going from a sylgard-184/glass interface over most of the wavelength range, but performs poorly at the red and blue ends. The realities of this project mean that we may just have to plow through and accept some throughput loss.

    I was also excited to see the work of Trinh et al. (2012) posted on the arxiv. Their work is exciting and has the potential to dramatically increase the signal-to-noise of background limited observations on large telescopes. It seems as if the technology is not quite there yet and their abstract is refreshingly honest:

    While these tests demonstrated high throughput and excellent suppression of the skylines by the OH suppression fibres, surprisingly GNOSIS produced no significant reduction in the interline background and the sensitivity of GNOSIS and IRIS2 is about the same as IRIS2.
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  4. SED Machine Lens Design

    This is a multipart post on the SED Machine lens design. In this post I will describe the front end of the SED Machine.

    Palomar 60-inch Telescope

    The Palomar 60 inch was built in the 1960s (Bowen & Rule 1962) to study objects that did not warrant time on the Big Eye of the 200 inch. Built when photographic emulsion was our most sensitive detector, the telescope has a short back-focal distance of about five inches.

    Automated in 2006 by a team of GRB hunters the robotic 60-inch telescope serves as the basic platform for the SED Machine.

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  5. SED Machine Bonding Woes

    The bond of achromatic doublet cam1/cam2 went down without a hitch. Cam 1 is a CaF2 element and Cam2 is an i-line glass from Ohara. The bond with Sylgard-184 looks clean.

    Camera 1/2

    Camera 1/2 doublet - a success. Cam 1/2 was bonded three days ago, and it will cure for about three more days before it will be installed in the lens barrel.

    Today Marin Anderson and I planned to bond collimator 1 and 2. Unfortunately, collimator 1 is AR coated on both sides. I've put a call into the vendor and need more information to proceed.

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