4ITM05 Input Test Mass for 4K interferometer

Back to Index of all LIGO COC
This web site is for posting useful documents related to the LIGO Core Optic Components design. The documents are for LIGO internal use only.
GariLynn Billingsley is the moderator of content.    Last updated November 21, 2001

Scatter (small integrating sphere)
31 ppm
Transmission (%)
AR coating (ppm)
Bulk Absorption (ppm/cm)
 3 prelim
Data at center only
Coating Absorption ppm (Stanford, witness samples)
HR side absorption (CIT - ppm)
AR side absorption (CIT - ppm)
Radius of Curv. (Km)
measured over 150mm diameter
See note 1 below
Surface error, central 80mm (nm rms)
0 .4406

Note1:  The range of radii of curvature measured for 4ITM05 were from 13.77K to 14.02K with the Average being 13.91K. The change in the measured saggita over this range is 3.3nm 
The preliminary measurement for this optic 13.58 was measured with a different insrument calibration (the instrument has since been rebuilt)  The new calibration (4-2005) is ... new, and will be refined with ongoing measurement.  The old measurement may be a better indicator of ROC match with other optics measured under the same instrument calibration.

Note 2:  The same streaks as seen on 4ITM01 (uncoated), 4ITM08, BS06 and one of the (now repolished) SPETMs can be seen on 4ITM05.  The streaks do not change the surface enough to put it beyond the specification that the surface error (with power and astigmatism subtracted) be less than 0.8nm rms

Phase map data  (about phase map format and filenames)
CIT Data covers the center 150mm
4ITM05-180, Dataset has Tilt and Power subtracted (Z1, Z2 & Z3), there are no missing data points within the set
Z36_4ITM03-180  Zernike Coefficients for this data set (about Zernike Coeffs, we use the Wyko definitions)
Radius of curvature:  See last column at Index

Physical configuration:  See drawings at Index
Nominal:  25cm x 10 cm
Wedge:  0º34'  Installed with the thick side up - this orientation corresponds to the - 180º phase map designated -180

Image of dataset 4ITM05-180