Subject: HRI-SIM TV1 Flash Report June 28, 2002 Date: Fri, 28 Jun 2002 18:49:11 -0600 From: Don Hampton Hello all, I'm picking up the ball from Dennis to let you know how testing went for the day. I worked CCD testing most of the day so will invite any of the SIM testers to correct any erroneous information. The multi-image issue that was baffling us at the end of the day yesterday was quickly resolved (so to speak) today when Dennis G. popped in a fold mirror and looked at the image directly, and could tell that we were just about 6 inches out of focus. After moving the table closer to the test chamber 6 nches it took little time to find distinct pinholes. They then proceeded to align in the spatial direction of the SIM, and check that the test telescope boresight is correct. With that accomplished the team made the first 5 in a set of knife edge tests that will determine the best position that puts the focus of the SIM test telescope on the slit. This will continue tomorrow. With lower dark current (detector is < 90 K, see below) a better measure of the total signal strength has been done. Casey finds signal all the way across the spectrum. The signal is low at short wavelengths, but should be due to the temperature of the source, not throuhgput of the system. The thermal performance of the SIM and radiator looks superb. The detector has crossed 90K and is still dropping, even while taking images with the FPA. We let the SIM bench drop below the nominal 135-137K operating range to help increase the rate of FPA cooling, but will bring it back up to 135-137K tonight so that it is stable tomorrow. Our rate of LHe usage is about 1/2 to 2/3 of our prediction (with a 2x margin built in) so the many dewars of LHe sitting in the hallways will be more than enough. There was one change in operation of the LHe plate: instead of allowing it to start warming before re-filling, the plate is filled every hour, or when the temperature begins to rise, whichever comes first. Overall the progress seems superb, and things look good fo continued progress. It is great to see UMd, JPL and Ball team members working together as a tight team. Looks like we have a good handle on three of the four degrees of freedom that we can control in the design. Don ----- Report from Casey Lisse ----- Date: Fri, 28 Jun 2002 20:58:23 -0400 (EDT) From: lisse@astro.umd.edu HRI SIM Notes 6/28/02 CML Tests conducted by Gallagher, van Cleeve, Klaasen, Lisse, and McLaughlin (Wellnitz on travel, Hampton babysitting the DI CCDs) HRI FPA at 92 K this morning, 88K in the evening. Optics bench at 125 K in the morning, 123 K in the evening. This is about 20K colder than we expect for nominal flight. The "Eight-Ball" vacuum chamber used for this test is working well. The problem with pressure spiking upon helium flow-in to the radiative cold plate solved itself overnight. The problem appears to have been due to low temperature volatiles freezing out on the helium cold plate early in the pump-out cycle; the cold plate transients up to 100 K at the beginning of a helium fill, as the transfer gas enters the plate. The dark current in the detector is way down. We are easily able to detect not only the W glow source, but room light radiation. CO2 and H2O lines were clearly detectable both on and off the glow source in one extracted row of the detector, in 1.5 sec integration time, in Mode 4. The array shows photoresponse throughout the 1.05 ­ 4.9 um spectral range of operation. We are able to do spectroscopic analysis on the array output. The array darks and biases subtract off well, as does a region of the array offset in the spatial direction from a source image. The background spectrum is well fit by a 300 K greybody at wavelengths above 4 um. Co-adding rows of the array in the spatial direction works well. The CO2 "doublet" at 4.25 m and the H2O broad resonance with an overall "triplet" structure, centered at ~2.7 um, are clearly detected. The dispersion of the array seems temperature dependent. Yesterday at the nominal temperature, the water and CO2 lines were almost bang on the predicted dispersion directions. Today, the CO2 lines fall at 4.4 um on the predicted dispersion plot, while the water lines were at within 0.05 um of the predicted position. A number of visitors have come through to check out the success of the test setup, including Alan Delamere and Sheree Burcar, Carl Hansen, and Blake Natker. The test electronics and software are working well, and are relatively transparent to the user. All 6 modes of the array have been commanded, and darks taken in each mode. DIVE is good for basic analysis, and supplemental IDL analysis on guest laptops plugged into a local hub is working well, with DHCP assigned IP addresses. The problem with finding the boresight yesterday has been solved. The primary image has been found, as has the prime spatial focus. The current effort is to perform a useful and accurate knife-edge test. After some effort, knife-edge tests were obtained in the cross- dispersion (spatial, or "vertical") direction of the array with the source placed at 6, 8, 10, 12, and 15 mm absolute position in the focus direction. A number of quick-look spectral products have been created. I have placed Them at ~lisse/deepimpact We will be working through the weekend, 10 AM ­ 8 PM Mountain Time. The alignment and focus tests are to run through Monday.