Figure 32. Overlapped Mode Exposure And Readout - Princeton Instruments Activity Tracker User Manual

Table of Contents

Chapter 6

Non-Overlapped Operation Exposure and Readout

Figure 33 illustrates exposure and readout when operating in the non-overlapped mode.

Non-overlapped operation occurs automatically any time the exposure time is shorter

than the readout time. Figure 33 contains four parts, each depicting a later stage in the

exposure-readout cycle.

Part 1 of the figure shows the array early in the exposure. The imaging cells contain charge

proportional to the amount of light integrated on each of them. The storage cells are empty

because no charge has been transferred to them. The arrows between adjacent imaging and

storage cells indicate the direction the charge will be shifted when the transfer occurs.

Part 2 of Figure 33 shows the situation early in the readout cycle. The charge in the imaging

cells has been transferred to the adjacent storage cells and up-shifting to the readout register

has started. Note that a second exposure doesn't begin while the readout is in progress.

Part 3 of Figure 33 shows the transfer to the output node. The lowermost cell in each

column is shown empty. Each row of charges is moved in turn into the readout register,

and from there to the output node and off of the array for further processing. The process

continues until all charges have been completely transferred out of the array. The

imaging cells are electronically switched off and do not accumulate any charge as the

readout takes place. Because this scheme is less time efficient than that used in the

overlapped mode, the frame rate may be lower in non-overlapped operation than it is in

overlapped operation with the some exposure time settings.

Exposure and Readout

Empty Readout Register. Exposure

has ended and image is being

transferred to storage cells.

Charge from first cell has been

shifted to the Output Node.