Teledyne Princeton Instruments PI-MAX 3, Системное руководство

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Chapter 11: WinX/32 and Dual Image
Feature (DIF)
The purpose of PI-MAX3 DIF is to acquire a pair of gated images in rapid succession.
The time between frames can be as short as 2

s (limit imposed by P46 phosphor decay
time) with exposure times as short as 5 ns. The DIF capability is ideally suited to
capturing rapidly evolving events. These experiments fall into two broadly applicable
categories:
• Single Trigger;
Single trigger experiments involve a single impulse event that evolves over time
such as a laser-induced plasma or luminescence decay.
• Dual Trigger.
Dual trigger experiments involve two impulses separated in time such as double
laser pulse velocimetry measurements.
11.1 Requirements
The PI-MAX3 must use an interline CCD. In addition, it is recommended that the
intensifier have a fast decay phosphor (P46). Since DIF operation involves acquiring
images in rapid succession, phosphor persistence can become the limiting factor in the
rate of image acquisition.
WinView/32 or WinSpec/32 software (version 2.5.26 or higher) can control the DIF
functionality of the PI-MAX3 and provide full access to the two DIF timing modes:
• Single Trigger;
• Dual Trigger.
11.2 Interline CCD Operation
An interline CCD consists of alternating columns of light sensitive pixels and storage
pixels. The light sensitive columns are referred to as the active area and acquire the
image. The storage pixels are called the masked area and store the image in the dark
while it is read out. With this architecture, the CCD can acquire a second image while
the first image is being read out, unlike a standard CCD, which must read out the first
image before the second acquisition can begin. The ability of the interline CCD to
quickly transfer an image under the masked columns and hold it there makes DIF
possible. As soon as the first image is acquired, it is shifted under the masked area and
held. The second exposure begins and is held in the active area until the first image has
been read out.