G. Sirri – INFN BO1 Test of Lamp with centering filament and mirror  An UPGRADE for the illumination with back mirror-lens and fine centering and focusing filament knobs has been realized by Nikon Italia and tested in Bologna  The CURRENT illumination by Nikon Italia is not a perfect Koehler system: 1.the filament image is pre-centered and can be neither fine centered nor focused; 2.the filament image doesn’t cover completely the aperture diaphragm. 3.a back mirror-lens is not present Consequences:  possible horizontal motion of grains images (shadows) during vertical displacement  possible limitation in the optical axial and lateral resolutions  loss of the light emitted by the filament G. Sirri for the Bologna group Neuchatel - 27 Sep 2006

G. Sirri – INFN BO2 Looking the exit pupil of the objective Remove an eyepiece and look at the exit pupil of the objective where is the image of the aperture diaphragm and of the filament (better with an auxiliary telescope) with frosted glass and green filter CURRENT: pre-centered* UPGRADE: Centering filament and back mirror Objective exit pupil. NA=0.9 Apert. Diaphragm NA=0.8 *Filament plugs forced in the center position but not focused Filament focused (magnified) image Mirrored image Neuchatel - 27 Sep 2006

G. Sirri – INFN BO3 Light distributions in the aperture diaphragms plane Light intensity (grey level) position CURRENT: The aperture diaphragm is not homogeneously illuminated. The borders are quite dark and eccentric lighter zones can behave as intense out-of-axis sources (and contribute to the “shadow”). UPGRADE The light distribution in the aperture plane is: Higher  more light Flatter  light gathered at high angles (better optical resolution)  isotropic flux in the field of view Light Intensity in the field of view: Voltage (a.u.) mean intensity (g.l.) CURRENT : 32767(max) 150 +/-10 CURRENT* : /-12 UPGRADE : /-10 Note: 0.5 ms exposure, green filter, frosted glass * Filament manually centered and focused by forcing the filament plugs… CURRENT CURRENT* UPGRADE Neuchatel - 27 Sep 2006

G. Sirri – INFN BO4 Grains Analysis with the UPGRADED Lamp Level-to-level distance ~ 0.5 µm Vertical clusters chains obtained using the libEGA of FEDRA UPGRADE Cluster area (pixels) cluster-to-grain_center vertical distance (µm) CURRENT* Cluster area (pixels) cluster-to-grain_center vertical distance (µm) z0 eZ z g grains cluster We have little changes in the grains shape: even if better illuminated the length of the grain image (the vertical resolution of the system) is strongly affected by the spherical aberration… 50X oil objective in the altered conjugates set-up green filter * Filament manually centered and focused by forcing the plugs Neuchatel - 27 Sep 2006

G. Sirri – INFN BO5 Check of the repeatability, efficiencies, … N2 N3 mean sigma repr. 1: (e)375 (e)345 (m) (s) % 2: (e)433 (e)389 (m) (s) % 3: (e)405 (e)380 (m) (s) % 4: (e)433 (e)396 (m) (s) % 5: (e)384 (e)344 (m) (s) % 6: (e)509 (e)460 (m) (s) % 7: (e)443 (e)412 (m) (s) % 8: (e)457 (e)400 (m) (s) % UPGRADE CURRENT* N2 N3 mean sigma repr. 1: (e)347 (e)321 (m) (s) % 2: (e)409 (e)379 (m) (s) % 3: (e)394 (e)356 (m) (s) % 4: (e)439 (e)389 (m) (s) % 5: (e)373 (e)334 (m) (s) % 6: (e)505 (e)463 (m) (s) % 7: (e)439 (e)413 (m) (s) % 8: (e)436 (e)390 (m) (s) % One example: 2x2 cm² on the pl36 of the reference brick 5 (TB June 2004) Selected 8 peaks, 3-times measured, repeatability 3 over 2 (+/- 2%) eChi2P<2.5 … therefore not much changes are obtained in the base-track measurements for what concerns repeatability, efficiency, purity, resolutions… * Filament manually centered and focused by forcing the plugs OVERALL ALIGNMENTS obtained with the UPGRADED illuminator some tracks have been measured and compared with the same tracks after a 180 degree rotation. The half mean value of the distribution of the tracks slopes differences before and after the rotation is (0.3 +/- 0.1) mrad Efficiencies, Purity, Resolutions are the same obtained in Bologna and already presented in the past meetings Neuchatel - 27 Sep 2006

G. Sirri – INFN BO6 Conclusions  The upgraded version of the lamp has been tested it is possible to align the filament without roughly forcing the filament plugs and fix the problem of the horizontal motion of the grains images during the vertical displacement (moving “shadows” effect). [Note that a similar effect is also due to the misalignments of the motorized axis] the light intensity is higher so that the green filter and the frosted glass can be used. the distribution of light rays gathered by the objective is more isotropic and the final numerical aperture of the system increases (however these improvements are limited by the spherical aberration in the current set-up). Neuchatel - 27 Sep 2006