From af7a483b5986980a78ca7f2562b6138e185a9397 Mon Sep 17 00:00:00 2001 From: "W. Trevor King" Date: Tue, 27 Jan 2009 09:45:24 -0500 Subject: [PATCH] Start bumps with the cantilever _off_ the surface. Photodiode sensitivity (and thus, bump slope) decreases as the zero-deflection photodiode input moves away from zero Volts. In order to mitigate the effect of this on our calibration, we need to keep track of the zero-deflection signal. By starting our bump off the surface, our bumps should always start and end in the zero-deflection regime. This will make analysis a bit more complicated though. I'll get to that next. --- calibcant/calibrate.py | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/calibcant/calibrate.py b/calibcant/calibrate.py index f78520f..269dafa 100755 --- a/calibcant/calibrate.py +++ b/calibcant/calibrate.py @@ -230,13 +230,14 @@ def vib(**kwargs) : # with proper spacing relative to the surface. @splittableKwargsFunction() -def move_just_onto_surface(stepper, zpiezo, Depth_nm=100, setpoint=2) : +def move_just_onto_surface(stepper, zpiezo, Depth_nm=-50, setpoint=2) : """ - Uses z_piezo_utils.getSurfPos() to pinpoint the position of the surface. - Adjusts the stepper position as required to get within stepper_tol nm - of the surface. - Then set Vzp to place the cantilever Depth_nm onto the surface. - + Uses z_piezo_utils.getSurfPos() to pinpoint the position of the + surface. Adjusts the stepper position as required to get within + stepper_tol nm of the surface. Then set Vzp to place the + cantilever Depth_nm onto the surface. Negative Depth_nm values + will place the cantilever that many nm _off_ the surface. + If getSurfPos() fails to find the surface, backs off (for safety) and steps in (without moving the zpiezo) until Vphoto > setpoint. """ -- 2.26.2