Subject: New DIS Quartz Slits (sknapp; 11June 96)
From: Steve Knapp
Submitted: Tue, 11 Jun 1996 10:57:21 -0600
Message number: 18
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New DIS Slits. [Best read in fixed width font.]
We have received new aluminized quartz slits for DIS. The slit widths
have been measured using the measuring engine at the Solar Observatory,
with mean values of:
211 (+- 4) and 274 (+- 7) microns (both N = 3, small samples)
or 1.24 and 1.61 arcsec.
The goal was to obtain slits with widths of 2.1 and 3.0 arcsec. The slits
were manufactured from and replace the previous (0.47 and 0.87 arcsec)
quartz slits. They were produced by Don Loomis using wire-shadow fixtures
made earlier by Mike Carr and the aluminizing was done by a sub-contractor.
APO supplied the fine piano wires. It is believed that the undersized slits
were the result of the aluminizing setup at the subcontractor; the ballistic
trajectories of the Al probably were not all near normal to the quartz plates,
quite likely if the subcontractor had several jobs in the vacuum chamber.
I regret that we did not obtain a 2 arcsec slit this time. I suspect,
however, that at least the 1.61 arcsec slit will see service straight away.
We are pursuing other sources (including our own aluminizing at the Solar
Observatory) for additional slits.
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For the record, here are some quantitative and qualitative observations of the
new slits (which I will call the "1.2 arcsec" and "1.6 arcsec" slits):
Provisional Name "1.2 arcsec" "1.6 arcsec"
Mean slit width, s 211 microns = 1.24 arcsec 274 microns = 1.61 arcsec
Standard dev (N = 3) 4 microns 7 microns
Quartz plate w x h 1.860 x 2.995 inches 1.865 x 2.996 inches
4.724 x 7.607 cm 4.737 x 7.610 cm
Thickness of plate 0.0624 to 0.638 inch (Not measured, assumed same)
Curvature of slit, 17 microns approx. 14 microns approx.
(peak displacement
of slit from straight
line in the central
5 cm of slit length)
Edge irregularities Clean, nothing obvious Clean, nothing obvious
Edge sharpness No "penumbra" observed in transmission, both slits
I guesstimate the accuracy of a single measurement with the engine at around
6 microns.
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Steve Knapp 11 June 1996
<sknapp@galileo.apo.nmsu.edu>
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