From jac17 at stanford.edu  Thu Jul 11 15:27:02 2002
From: jac17 at stanford.edu (john chiaverini)
Date: Thu, 11 Jul 2002 15:27:02 -0700 (PDT)
Subject: question about lighting
Message-ID: <Pine.LNX.4.44.0207111520490.14858-100000@cardinal2.Stanford.EDU>

wafersaw users,

i'm hoping someone can help me with a problem i'm having.  i'm trying to
cut up a wafer that has a layer of gold all over the top surface.  the
wafer has etched pits that i would align the cutting to, and they have
gold in them as well.  the video camera does this weird auto-adjusting
thing when it thinks too much light is coming back (like off the very
reflective gold).  it adjusts the image so i can't see contrast between
the surface and the pits.  i know it is doing some adjusting, as when i
look at the wafer edge, and the gold from the wafer takes up only half the
image, the image looks fine.  and i can momentarily put something in the
way of the camera, and then remove it, and for a second (before the camera
adjusts) i can see an image with more contrast.

does anyone have any experience with this?  there doesn't seem to be an
obvious way to adjust the camera, and len says the light has a fixed
voltage.  i don't really want to put another layer on top of this wafer.

thanks...


john chiaverini  /  jchiaverini at stanford.edu

the highest purpose is to have no purpose at all. this puts one in accord
with nature in her manner of operation.              -john cage, composer