CD16 optics desired

Here's the email I sent out with CD 16 optics choices.

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Hi Folks,

Here's my guess at a filter list for CD16.  I'll post it on the blog, too.  It is also in the dropbox EE/docs/EXEScomponents.xlsx

Filter slot

1) 18a+ZnSe blocker (no change)

2) BBP5500_6000+CaF2 (no change)

3) open (no change)

4) N04679-4 + CaF2 blocker (remove N04582-8+MgF2 blocker)

5) Reading 6.2 + MgF2 blocker (move BP-6000-250 +MgF2 to decker slot 3

6) N07466-9 + CaF2 (remove BP4990_265+CaF2)

7) BP-6600-320+MgF2 (no change)

8) Soifer (no change)

9) N07053+9 + CaF2 blocker (no change)

10) BBP5030_5725+blocker (no change)

11) N07904-9 +CaF2 blocker (remove N10247-9 + CaF2 blocker) 

12) BP14100_850 (no change)

Decker slot:

1) BBP_8000_1100 + BaF2 blocker (no change)

2) BBP_4700_5615 + MgF2 blocker (install MgF2 blocker)

3) BP-6000-250 + MgF2 (moving from filter slot 5)

4) OCLI Q + BaF2 blocker

Lens wheel:

1) mirror

2) open

3) CaF2 window (38 mm) (remove ZnSe 38 mm window)

4) 1.5" diam KRS5 lens (no change, but may want to move toward detector - see below)

5) 1.5" ciam ZnSe lens (no change, but may want to move toward detector - see below)

6) BaF2 window (38 mm) (no change)

Detector position:

We should be back to where we were in CD13.  I believe this is 3. mm back from where we were in CD14.  Based on the images of the pupil in CD14

http://codgermmck.blogspot.com/2013/04/taas-summary.html

I think we want to leave the lenses where they are.  My reasoning is that the ZnSe was further from the detector in CD14 and seemed to provide sharper images.  The ZnSe is currently further from the detector.  When we move the detector back, the KRS5 lens should be about where the ZnSe lens was and the ZnSe lens will be even further away from the detector.  Note that we may want to use the echelle mirror to investigate focus for the cold stop during CD16.

-matt

Remeasured Detector distances for CD13, CD14 and CD15

Detector Measurements

We measured the detector distance for the CD13 D-box and we remeasured the tilted CD14 D-box using a microscope in Emmett’s machine shop.

D= Detector distance = distance from the O-box wall to the central column detector surface.

Prior to these measurements, we thought that D= 14.5 mm for CD13, based on the mechanical drawing and adjusted for the widths of the 8 G10 spacers that were actually used.

The tilted detector box was measured with a bare-mux installed prior to CD14 by Ryan Walker, and had a central column distance of D=12.61 mm (see http://codgermmck.blogspot.com/2013/02/tilted-detector-distances.html).

Here are the new measurements:

CD13 -- new measurements: D=15.53mm (8/27/13)

CD14 -- new measurements: D=12.53mm to central column (8/26/13)

left edge(blue): d=10.58mm, right edge(red): d=14.49

(previous measurements by R.W. were 12.61 mm to central column, 10.63 and 14.59 for left and right edges respectively)

CD15 -- detector box tilted, with 1.89 mm spacer plate installed

new measurements: 12.53mm+1.89mm = D = 14.43mm to central column

left edge(blue): d=12.47mm, right edge(red): d=16.38

So the equation for the column position for CD15 is

d=0.003818*column+12.47 mm

The detector was at the CD13 distance at column x=802 during CD15. This is close to where the best focus was measured for the medium resolution mode.

Bounce Tests, CD015

Performed by Kristen and Curtis.
pp 23-24 of Lab Book VI, 8/16/13

The purpose was to evaluate EXES sensitivity to vibrations when motor hold currents are on/off and when the flip/door mirror stops are "wound" against, or when the flip/door mirrors are "hanging".

This test used 14 1 egos sequences (N6 D). We took one set as a baseline.
Then another set with a mechanical shock, executed at the beginning of frame 4.
The counts in each frame were linearized. 

The "mechanical shock" was as follows.

Using the orange plastic coated mallet from Dave Black's toolbox.
Hold handle in one hand, and lift hammer end 6" above forward end ring. At end of frame 3, let drop.

The images show double subtracted frames to show small differences in the high or medium spectra in each interval.

We call the "baseline" the sequence where there was no mechanical shock.
We call the "event" the sequence where the hammer was dropped at the end of "3"

For comparison, we show a "BEFORE" frame, that is baseline(2-1)-event(2-1) or [baseline(*,*,2)-baseline(*,*,1)]-[event(*,*,2)-event(*,*,1)]. This should just be noise in all cases, since in precedes the hammer drop for both sequences.

The After frames are baseline(6-5)-event(6-5) or [baseline(*,*,6)-baseline(*,*,5)]-[event(*,*,6)-event(*,*,5)], and these should show smearing or shifts if there is significant motion induced in the mechanisms by the hammer.

                  

HIGH-RES: These first images give an idea of the counts in a single interval (single subtraction, not double):

                                     

HIGH-RES, Wound against stop (wall). Motors Disabled

                                      

HIGH-RES, Wound against stop (wall). Motors Enabled

                                    

HIGH-RES, Flip mirror floating, Motors Enabled

                            

HIGH-RES, Flip mirror floating, Motors Disabled




---------------------------------------Medium Res Spectra-------------------------

                              

MEDIUM-RES: These first images give an idea of the counts in a single interval (single subtraction, not double):

                        

MEDIUM-RES, Flip mirror floating (aligned). Motors Enabled

                                      

 MEDIUM-RES, Flip mirror floating (aligned). Motors Disabled

                       

 MEDIUM-RES, Flip mirror wound against stop (wall). Motors Disabled

                     

 MEDIUM-RES, Flip mirror wound against stop (wall). Motors Enabled.

Read Noise

From the Noise data from CD15,  (cd15_13jun/41/*618 to 622 (room) and 623 to 627 (mirror)), I've done some analysis.  I think the mirror data are totally dominated by read noise and the room data are dominated by non-linearity.  This post is for the read noise.

The five FITS files were each NSNSNSD x 16 repeats stored as 1024,1024,64 fits files.  ctdelay = 70 which corresponds to a frame time of 2.055 seconds.

I read all files in.  The first two NSNSNSD patterns for both room and mirror had clear offsets, so I discarded those.  Now I had two 1024,1024,56,5 arrays.

For the mirror, I took the difference of N_2 and N_1 and N_4 and N_1.  I now have two 1024,1024,14,5 arrays.  I also noticed the median of each difference was different for the different files by a few DN.  I subtracted off the median of each file's difference and added the median of the first file to try and remove this offset.

The signal should increase by a factor of 3 between these two differences.  The actual value is closer to 2.8, indicating non-linearity hits early.

I did the same processing on the room data for N_2 - N_1 and adjusting the medians of each file.

I reformed the data to 1024,1024,70 arrays so that I could look at the median and standard deviation of each pixel through the time series.  The median and noise images show patterns, but since I'm looking at each pixel through the 70 images separately, I don't think that matters too much.

The read noise is clear in the mirror data.  That figure is below.   There is some difference in the level of read noise that depends on the amplifier chain (columns 1,5,9...; 2,6,10...; ...).  Clearly, the noise is about the same for both differences, even though the signal is almost 3x larger.  This makes me think we're limited by read noise.

The noise vs signal for each pixel in a 1024,1024 by 70 time series.  The blue is the difference of sample 4 and sample 1 in a NSNSNSD pattern.  The black (left hand side) is the difference of sample 2 and sample 1.  

• all pixels: median noise = 8.99
• columns 0,4,8,...: median noise = 8.82
• columns 1,5,9,...: median noise = 11.06
• columns 2,6,10,...: median noise = 8.92
• columns 3,7,11,....: median noise = 8.07

Since the noise is coming from a difference, it is square root 2 higher than for a single read.  Taking the median = 9.0 ADU, the single read = 6.4, and the number of electrons = 222 e-.  In comparison, John Lacy found read noise around 3.5 ADU for 2x2 pixel averaging (=> 7 ADU for difference => 175 e-). We really need to get this level of read noise down.  I thought we were at 70 e- for a single read.  I suppose there could be some other noise source that I'm not correcting for that is dominating.

From the time series looking at the room, I got the corresponding noise vs signal plot below.  The noise is starting to come off the 9 ADU level.

My whole point of looking at these data was to try and recalculate eta, g, and beta.  I don't think that is possible with readnoise dominated data.  I'll try to linearize the room data and see if I can come up with a good answer.

CD015 High-res 14um Performance

We found the 25 diagonal, 13T/12T on echelon/echelle to produce the best performance on the right side of the detector.

Here we look in detail at the slit feature resolutions.

Resolution in terms of km/s

Resolution in terms of R=lambda/dlambda

Acceptance angle from TAAS measurements in CD015

During CD015 we took pupil imaging data of the SCHP with the goal of finding the solid angle accepted by EXES, in part so that we can settle question about our throughput calculations. Note that the KRS5 lab entrance window (not the flight CSI window) was installed for CD015

The data was taken on 6/27/13, and is stored in /data/cd15_13jun/27/

The configuration was for pupil imaging:
filter: N04582-8
aperture: slit7 crossed with 14-pix decker dash
lens wheel: ZnSe
flip: bypassing echelon grating
echelle angle: -1.2 degrees

SCHP temperature was 150 C
For files cold.lab.00202.fits-cold.lab.00211.fits, a mask (a hole-punched index card) with a 1/4" hole was placed in front of the ~2.5" SCHP, restricting the size.

The pupil images showed the circular outline of the cold-stop and a faint looking blob corresponding to the restricted, heated SCHP. We moved the X and Z stages of the SCHP by known amounts with the SCHP control software in order to find the scaling of EXES pixels in pupil mode to physical position of the SCHP.

The top image shows the pupil image when the SCHP was located at its "central boresite position" given by Ted Dunham's measurement with HIPO.
SCHP stage positions (X,Z)=(140.5mm, 115.3mm)
EXES pixel position (X,Y)= (364,523)

The bottom image shows a second position of the SCHP stage:
SCHP stage positions (X,Z)=(200mm,115.3mm)
EXES pixel position (X,Y)=(316,568)

The pix/mm scaling, based on 10 different positions of the SCHP stage, is:
1.18 +/- 0.04 pixels/mm

The radius of the cold-stop boundary is 105+/- 5 pixels.

The distance from the rear surface of the entrance window to the SCHP is 116.2" +/- 0.1" or 2950mm +/- 3mm.

Therefore, the acceptance half-angle is:

arctan(105 pix /1.18 pix/mm/2950mm)= 0.030 rad +/- 0.002 rad

Compare to the value 0.0251 rad determined with the soldering iron experiment in CD014 (http://codgermmck.blogspot.com/2012/03/acceptance-angle-of-exes.html)

(However,  note that we used the distance to the back surface of the window for the angle determination, rather than the first focus behind the window lens.)

PART 2:

What is the angular size and position of the SOFIA secondary?

From the Zemax drawing (...KRS5 window.zmx) we have:
D_secondary=352 mm

1764.124 mm Secondary to tertiary  
4785 mm        Tertiary to "Inboard EXES ..."
25.4 mm         "Inboard EXES ... " to "Outboard EXES ..."
85.165 mm     "Outboard EXES ..." to Window surface
3.7mm            Window thickness
------
6663.39 mm

1/2 Angle_secondary= arctan (352/2/6663.39)= 0.0264 rad 

This is smaller than our measured cold-stop diameter ...

In cold.lab.00202.fits
The center of the pupil is (370, 530) pix


The center of the point source SCHP at the boresite position is (364, 523) pix


When the mask was taken out of the SCHP, the center appears to be (359,529) pix
(cold.lab.00212.fits).
In the figure below, the red circle is our cold-stop (radius 105 pix). The yellow is the angular radius of the secondary (r= 92 pix), placed at the point source center. The blue circle is the angular radius of the secondary, placed at the SCHP center, as determined when the mask was removed. I'd trust blue over yellow, since the "point-source" mask was placed over the center of the SCHP by eye.