## Gun Tilt Balance - Lens Cont (2) - VR1 = Tilt X Balance - VR2 = Tilt Y Balance ## Using memory write commands to turn the coils on and off - The address for the scan coil enable disable chip is - `7F855` - The data is: - `CO` - Both coils off - `80` - Upper coil off - `40` - Lower coil off - `00` - all coils on - To use the command, hit INS on the keyboard, followed by `WR 7F855 *data*` - Example `WR 7F855 80` would turn the upper coil off and `WR 7F855 00` would turn it back on - ![[New Drawing 3.png|lg]] ## Orthogonality and deflection The lower and upper deflectors are physically mounted to separate sections of the column. You have to electronically align the lower deflectors, then physically and electronically align the upper deflectors to the lower deflectors. The physical alignment is carried out by adjusting bolts on the column with Allen keys, and rotating sections of the column relative to other sections. - Lower - Paramaters - 25kv - WD15 (OL Course 125, OL Fine 512) - Stage: WD15, fine z 2mm - CL = 9 - Slow3 Scanning - Get image of test sample, use lens clear repeatedly. - Set magnification to 200x - Turn on only the lower deflectors - Move the stage in X, look for the image to move only in the horizontal direction. - Use VR5 (HL - Horizontal Lower) on Mag Cont PB (U9) to adjust so the object moves horizontally - If you are aligning against the built in CRT, use the B-Up mode to display the cross hairs on screen and align against this. This assumes your cross hairs are aligned. - If using an external scan generator see if it has options for cross hairs - Should be able to move all the way from left side of screen to right side of screen without moving - Make sure the sample is in focus and horizontal, but only use stage controls (keep OL coarse and fine as set earlier) - With a grid in, use VR6 (VL - Vertical Lower) on Mag Cont PB (U9) to adjust vertical orthogonality relative to the vertical bars of the cross hair. - Upper - You need to align the lower first - Don't have a [[LAB6]] installed while doing this, it could have some gas bursts while moving the sections around, its just sliding on the o-rings - Loosen the upper deflector coil screws just enough to let sections rotate. Maybe 90°. - to do: add figure illustrating what screws - Turn on only the upper deflector - Turn the upper deflector to align the horizontal direction of movement with the horizontal cross hairs - Use VR7 (VU - Vertical Upper) on Mag Cont PB to align the vertical movement/gridbar with the vertical axis of the cross hair. ## Magnification Alignment - Conditions - 25kV - WD15 (OL Course 125 Fine 521) - CL (Probe Current): 9 - 200X - Total - Load 100µm grid - Both deflectors on - The horizontal distance of 3 100µm grid squars and bars should be 120mm on the CRT (+-1mm) - Horizontal: Use VR1 on Mag Cont PB - Vertical: VR3 Mag Cont PB - Upper Coils Magnification - Load 25µm grid - Upper deflector on, lower off - 200x magnification - Horizontal: VR2 (HG) on Mag Power Amp - Vertical: VR5 (VG) on Mag Power Amp - 1 grid interval = 120 mm on screen (-1mm) ## Mag-range offsets - - Checking for reasonably orthogonal - ![[Pasted image 20230206183536.png]]