Focus Check, Medium Resolution+Pinhole in CD27

Here is the analysis performed by Curtis and me of medium-resolution spectra taken with the pinhole slit setting in order to find find the best focus and best detector position. The data are taken during CD27 and involve the files between gascell.lab.00272.fits and room.lab.00281.fits. The gas cell was filled with C2H2 and data taken at the 4th order Q-branch (WN = 731 cm^-1). 


We began with 2 turns CCW from a position defined to be zero turns on the echelle mirror screwdrivers and stepped in increments of 1 turn CW all the way to +2 turns CW from our zero position. Data were taken passing back through zero net turns. 

An OTPAT of N3 S7 N2 D0 T0 was used for the gas cell, and N2 D0 T0 for the room. The gas cell images were examined by subtracting the 2nd -- 7th planes (im1[*,*,1]-im1[*,*,6]), while the room had the 2nd -- 3rd planes (im2[*,*,1]-im2[*,*,2]). A scaled room frame was then subtracted from the gas cell and examined with display and clickfit with the /twod option called.

A screenshot of the gas cell - scaled (0.9 x) room with the four lines I selected in clickfit indicated by being at the center of the boxes.

A plot of the major (green) and minor (red) FWHM (in pixel space) from clickfit through the different turns on the echelle screwdrivers. Negative values are CCW & positive CW.

A plot of the ratio of major/minor FWHM vs number of net turns. Negative values are CCW & positive CW.