S e t - U p

Here are a few example CCD images showing what you should see through Taurus/TTF in a few of its different imaging modes.

Matrix Mask (Direct Imaging):

taken 29-Apr-97

Shows main matrix pattern with ghost image offset to the right. Ghost spots may not be obvious at first as they are relatively faint. Exposure time used here: 100 seconds.

Copper-Argon Lamp (Charge-Shuffle Imaging):

taken 29-Apr-97

Charge-shuffling in 80 steps through narrow horizontal slit (special "80-shuffle slit") on Cu Ar lamp. Blocking filter used: 710. Scan range: Z= 0 to 790 in steps of 10. Exposure time: 1 second (per shuffle). See that we image 2 orders of interference across this range of Z, i.e. the pattern of emission-lines repeats itself twice.

What You're Seeing with a Charge-Shuffle Image:


(A) Usually (although not always) a shuffle frame comprises 80 separate images of the slit where each image is taken at different TTF plates spacings, i.e. wavelengths or frequencies (f1, f2....fN).

(B) The raster image illustrated in A produces a long-slit spectrum where the degree of curvature in the lines is directly proportional to the gap spacing (the TTF has little curvature at the smallest spacings; the 200um has huge curvature).

QI Lamp (Charge-Shuffle Imaging):

taken 29-Apr-97

Identical set-up as above (same blocking filter, range of Z) except used on the QI lamp. The bright arcs are probably not emission-lines but peaks caused by the overlap of light from adjacent orders.

Incorrect CCD Rotation (Charge-Shuffle Imaging):

taken 29-Apr-97

When things are not quite right! Shows the appearance of a shuffle image (same set-up as above) when the CCD is rotated 90 degrees the wrong way. Having the CCD perpendicular to the shuffle slit mask produces a bright smeared line containing no spectral information.

Maximum Tilt (Direct Imaging):

taken 29-Apr-97

The ghost image on this frame shows the maximum distance that ghosting can be offset from the field. For this frame, TTF was set at maximum tilt by removing the kinematic mounts. The change compared to the image at top is small. Exposure: 100 seconds.

Maintained by Heath Jones