Photometrics Prime sCMOS User manual

USER MANUAL

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Prime™ sCMOS User Manual
© Copyright 2016 Photometrics
3440 East Britannia Drive
Tucson, Arizona 85706
Tel: [phone]
Fax: [phone]
All rights reserved. No part of this publication may be reproduced by any means without the written permission of
Photometrics.
Acrobat and Reader are registered trademarks of Adobe Systems Incorporated in the United States and/or other countries.
Photometrics and PVCAM are registered trademarks of Roper Technologies.
Prime is a trademark of Photometrics.
Intel Core is a trademark of Intel Corporation in the U.S. and/or other countries.
Windows is a registered trademark of Microsoft Corporation in the United States and/or other countries.
All other brand and product names are the trademarks of their respective owners and manufacturers.
The information in this publication is believed to be accurate as of the publication release date. However, Photometrics does
not assume any responsibility for any consequences including any damages resulting from the use thereof. The information
contained herein is subject to change without notice. Revision of this publication may be issued to incorporate such change.

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Prime™ sCMOS User Manual
LIMITED WARRANTY
Photometrics (“Photometrics,” us,” “we,” “our”) makes the following limited warranties. These limited warranties
extend to the original purchaser (“You”, “you”) only and no other purchaser or transferee. We have complete
control over all warranties and may alter or terminate any or all warranties at any time we deem necessary.
Basic Limited Two (2) Year Warranty
Photometrics warrants this product against substantial defects in materials and/or workmanship for a period of
up to two (2) years after shipment. During this period, Photometrics will repair the product or, at its sole option,
repair or replace any defective part without charge to you. You must deliver the entire product to the Photometrics
factory or, at our option, to a factory-authorized service center. You are responsible for the shipping costs to return
the product. International customers should contact their local Photometrics-authorized representative/distributor
for repair information and assistance, or visit our technical support page at www.photometrics.com.
Limited One (1) Year Warranty on Refurbished or Discontinued Products
Photometrics warrants, with the exception of the CMOS or CCD image sensor device (which carries NO
WARRANTIES EXPRESS OR IMPLIED), this product against defects in materials or workmanship for a period of
up to one (1) year after shipment. During this period, Photometrics will repair or replace, at its sole option, any
defective parts, without charge to you. You must deliver the entire product to the Photometrics factory or, at our
option, a factory-authorized service center. You are responsible for the shipping costs to return the product to
Photometrics. International customers should contact their local Photometrics representative/distributor for repair
information and assistance or visit our technical support page at www.photometrics.com
Normal Wear Item Disclaimer
Photometrics does not warrant certain items against defect due to normal wear and tear. These items include
internal and external shutters, cables, and connectors. These items carry no warranty, expressed or implied.
Software Limited Warranty
Photometrics warrants all of our manufactured software discs or memory devices to be free from substantial
defects in materials and/or workmanship under normal use for a period of one (1) year from shipment.
Photometrics does not warrant that the function of the software will meet your requirements or that operation will
be uninterrupted or error free. You assume responsibility for selecting the software to achieve your intended results
and for the use and results obtained from the software. In addition, during the one (1) year limited warranty, the
original purchaser is entitled to receive free version upgrades. Version upgrades supplied free of charge will be in
the form of a download from the Internet. Those customers who do not have access to the Internet may obtain the
version upgrades on a CD ROM or USB memory device from our factory for an incidental shipping and handling
charge.

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Prime™ sCMOS User Manual
Owner’s Manual and Troubleshooting
You should read the owner’s manual thoroughly before operating this product. In the unlikely event that you should
encounter difficulty operating this product, refer to the owner’s manual. If the problem persists, please contact the
Photometrics technical support staff or an authorized service representative.
Your Responsibility
The above Limited Warranties are subject to the following terms and conditions:
You must retain your bill of sale (invoice) and present it upon request for service and repairs or provide other proof of
purchase satisfactory to Photometrics.
You must notify the Photometrics factory service center within thirty (30) days after you have taken delivery of a
product or part that you believe to be defective. With the exception of customers who claim a “technical issue” with
the operation of the product or part, all invoices must be paid in full in accordance with the terms of sale. Failure to
pay invoices when due may result in the interruption and/or cancellation of your two (2) year limited warranty and/
or any other warranty, expressed or implied.
All warranty service must be made by the Photometrics factory or, at our option, an authorized service center.
Before products or parts can be returned for service you must contact the Photometrics factory and receive a return
authorization number (RMA). Products or parts returned for service without a return authorization evidenced by an
RMA will be sent back freight collect.
These warranties are effective only if purchased from the Photometrics factory or one of our authorized
manufacturer’s representatives or distributors.
Unless specified in the original purchase agreement, Photometrics is not responsible for installation, setup, or
disassembly at the customer’s location.
Warranties extend only to defects in materials or workmanship as limited above and do not extend to any product or
part which has:
•been lost or discarded by you;
•been damaged as a result of misuse, improper installation, faulty or inadequate maintenance, or failure
to follow instructions furnished by us;
•had serial numbers removed, altered, defaced, or rendered illegible;
•been subjected to improper or unauthorized repair; or
•been damaged due to fire, flood, radiation, or other “acts of God” or other contingencies beyond the
control of Photometrics.

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Prime™ sCMOS User Manual
After the warranty period has expired, you may contact the Photometrics factory or a Photometrics-authorized
representative for repair information and/or extended warranty plans.
Physically damaged units or units that have been modified are not acceptable for repair in or out of warranty and will
be returned as received.
All warranties implied by state law or non-U.S. laws, including the implied warranties of merchantability and fitness
for a particular purpose, are expressly limited to the duration of the limited warranties set forth above. With the
exception of any warranties implied by state law or non-U.S. laws, as hereby limited, the forgoing warranty is
exclusive and in lieu of all other warranties, guarantees, agreements, and similar obligations of manufacturer or seller
with respect to the repair or replacement of any parts. In no event shall Photometrics’ liability exceed the cost of the
repair or replacement of the defective product or part.
This limited warranty gives you specific legal rights and you may also have other rights that may vary from state
to state and from country to country. Some states and countries do not allow limitations on how long an implied
warranty lasts, when an action may be brought, or the exclusion or limitation of incidental or consequential damages,
so the above provisions may not apply to you.
When contacting us for technical support or service assistance, please refer to the Photometrics factory of purchase,
contact your authorized Photometrics representative or reseller, or visit our technical support page at www.
photometrics.com. www.photometrics.com.
U. S. Government Restricted Rights
The software and documentation are provided with Restricted Rights. Use, duplication, or disclosure by the
Government is subject to restrictions as set forth in subparagraph (c)(1)(ii) of the Rights in Technical Data and
Computer Software clause at DFARS 252.227-7013 or subparagraphs (c)(1) and (2) of the Commercial Computer
Software-Restricted Rights at 48 CFR 52.227-19, as applicable. Contractor/manufacturer is Photometrics, 3440 East
Britannia Drive, Tucson, AZ 85706.
This license is effective until terminated. It will terminate upon the conditions set forth above or if you fail to comply
with any term hereof. Upon termination, you agree that the software and accompanying materials, and all copies
thereof, will be destroyed. This agreement is governed by the laws of the State of Arizona. You acknowledge that you
have read this agreement, you understand it, you agree to be bound by its terms, and that this is the complete and
exclusive statement of the agreement between you and Photometrics regarding the software.

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Prime™ sCMOS User Manual

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Prime™ sCMOS User Manual
Table of Contents
Overview ........................................................................................................................ 1
About This Manual .......................................................................................................................... 1
Precautions...................................................................................................................................... 1
Environmental Requirements ........................................................................................................... 2
Storage Requirements ..................................................................................................................... 2
Microscopes, Lenses, and Tripods ................................................................................................... 2
Repairs ........................................................................................................................................... 2
Cleaning ......................................................................................................................................... 2
System Installation........................................................................................................... 3
Introduction .................................................................................................................................... 3
Getting to Know Prime .................................................................................................................... 4
Software Compatibility Requirements ............................................................................................. 5
Host Computer Requirements ......................................................................................................... 5
Software Installation ....................................................................................................................... 5
Installing the PCI Express Interface Card ......................................................................................... 6
Connecting Prime to the PCIe Bus ................................................................................................... 8
Connecting Prime with USB3.0........................................................................................................ 9
Theory of Operation .................................................................................................... 10
Introduction .................................................................................................................................. 10
CMOS Image Sensor Structure ..................................................................................................... 10
Gain Combining ........................................................................................................................... 11
Rolling and Global Shutter Readout .............................................................................................. 12
Digital Binning ............................................................................................................................... 13
Sensor Clearing.............................................................................................................................. 13
Bias Offset..................................................................................................................................... 14
Pixel Noise Filters........................................................................................................................... 14
Operating Features ....................................................................................................... 18
Introduction .................................................................................................................................. 18
Bias Offset Setting ......................................................................................................................... 18
Clearing Mode Selection ............................................................................................................... 18
Single and Multiple Regions Of Interest......................................................................................... 19
Device Synchronization (Triggering)............................................................................................... 21
Trigger Modes ............................................................................................................................... 21
Expose Out Behaviors.................................................................................................................... 22
Multiple Output Triggers ............................................................................................................... 25

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SMART Streaming ......................................................................................................................... 25
Fan Speed Control and Liquid Cooling........................................................................................... 26
Advanced Features ........................................................................................................................ 27
Time Stamps.................................................................................................................................. 28
Troubleshooting ............................................................................................................ 29
System Does Not Boot Normally ................................................................................................... 29
New Hardware Found Dialog Box Does Not Appear ..................................................................... 29
Images Not Displayed ................................................................................................................... 30
Camera Running Too Warm ......................................................................................................... 30
PVCAM Error Message Appears ................................................................................................... 30
Lengthy Pauses During Imaging ................................................................................................... 30
Basic Specifications ....................................................................................................... 31
Prime sCMOS: Front, Side And Rear Views ................................................................................... 31
Camera Weight ............................................................................................................................. 31
Power Supply Specifications .......................................................................................................... 32
Liquid Cooling Setup Instructions ................................................................................. 33
INDEX ............................................................................................................................ 34

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Prime™ sCMOS User Manual
Chapter 1.
Overview
This Prime sCMOS User Manual is divided into five chapters. Photometrics recommends
you read this entire manual before operating the camera to ensure proper use. The
chapter contents are briefly described below.
Note: The information in these chapters applies only to the Prime sCMOS camera and
is currently not applicable to any other Photometrics camera.
•System Installation — Instructions for connecting the Prime sCMOS
camera to a computer via the PCI Express interface card or the USB3.0 bus.
•Theory of Operation — A basic overview of sCMOS camera technology as
used in the Prime sCMOS camera.
•Operating Features — Prime features and how to optimize them for speed
and sensitivity, and how to use the different trigger modes.
•Troubleshooting — Answers to common camera system questions.
•Basic Specifications — Specifications for Prime system components.
Precautions
The CCD and other system electronics are extremely sensitive to electrostatic discharge
(ESD). To avoid permanently damaging the system, please observe the following
precautions:
•If using high-voltage equipment (such as an arc lamp) with the camera
system, turn the camera power on last and when powering down, power
the camera off first.
•Never connect or disconnect any cable while the system is powered on.
•The camera’s power should be switched off before disconnecting any
camera system cables. However it is not necessary to power off the
computer to detach the cables.
•Use caution when triggering high-current switching devices (such as an arc
lamp) near the system. The image sensor can be permanently damaged
by transient voltage spikes. If electrically noisy devices are present, an
isolated, conditioned power line or dedicated isolation transformer is highly
recommended.
•Always leave one inch of space around the camera’s external cooling fins
for airflow.
About This
Manual

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Prime™ sCMOS User Manual
Environmental
Requirements
•Do not operate the camera without cooling (air or liquid).
•Never open the camera. There are no user-serviceable parts inside the
Prime sCMOS camera. Opening the camera voids the warranty.
•Use only the PCI Express interface card, cables and power supply
designated for this camera system. Using non-Prime cables, PCI Express
interface cards or power supplies may result in permanent damage to the
system.
•Do not use a C-mount lens with optics that extend behind the lens flange.
Storage
Requirements
Store the Prime sCMOS camera system in its original containers. To protect the system
from excessive heat, cold and moisture, store at an ambient temperature between
-20°C and 60°C with a relative humidity of 0% to 90%, noncondensing.
The Prime sCMOS camera system should be operated in a clean, dry environment.
The camera system’s ambient operating temperature is 0°C to 30°C with 80% relative
humidity, non-condensing.
Microscopes,
Lenses, and
Tripods
Repairs
Please save the original packing materials so you can safely ship the camera to another
location or return it for repairs if necessary. The Prime sCMOS camera system contains
no user-serviceable parts. Repairs must be done by Photometrics. Should the camera
system require repairs, please contact Photometrics Customer Service.
Note: Do not open the camera. Opening the Prime sCMOS camera voids the warranty.
The camera has a standard threaded video mount and can be mounted to any
microscope that accepts a standard C-mount adapter. The camera also allows you to
install any lens that is compatible with a standard threaded video mount as long as its
optics do not extend behind the flange of the lens. Prime can be mounted to optical
tables, tripods and copy stands using the eight ¼-20 threaded attachment points
located near the camera front and rear on all sides (see figure 1)
Cleaning
Clean exterior surfaces of the camera with a dry, lint-free cloth. To remove stains,
contact Photometrics Customer Service. To clean the camera’s imaging window, use
only a filtered compressed-air source. Hand-held cans are not recommended as they
may spray propellant onto the window. Do not touch the window.

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Prime™ sCMOS User Manual
Chapter 2.
System Installation
Introduction
The Prime sCMOS camera system includes the following hardware components:
•Prime sCMOS Camera
•PCI Express (PCIe) interface card
•PCI Express data cable
•USB 3.0 SuperSpeed A to B data cable
•A 12V/12A power supply with international power cord set
•I/O to 8 BNC trigger break out cable, part number CBL-IO-8-BNC
•USB memory device containing PVCAM library and drivers
•Quick Installation Guide
Prime system components are linked by the PCI Express or USB3.0 data cable and
controlled by the host computer system. All of these hardware components should be
included with the shipment. Keep all the original packing materials so you can safely
ship the camera to another location or return it for service.
If you have any difficulty with any step of the instructions, contact Photometrics
Customer Service.
Carefully review the Precautions section in the previous chapter before performing
any of the procedures outlined in this chapter. Again, use only a Prime sCMOS PCI
Express data cable and Prime PCI Express interface card with the camera. Using a
different cable or interface card may result in permanent damage to the system.

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Prime™ sCMOS User Manual
Getting to Know
Prime
Highlights of the Prime sCMOS camera are shown below: The Prime package includes
the PVCAM drivers designed to allow you to use this camera with a variety of third
party imaging software - To see a list of supported software, visit the Photometrics
website.
•USB3.0: Lower Speed Data Connection.
•DATA : High Speed PCI-Express Connection.
•Out/In: Liquid Cooling Connections.
•Initializing: LED blinking indicates the camera is booting up.
•Power Switch: Turns the camera on and off.
•Trigger: Hirose HR10A-10R-10S for use with Photometrics’ trigger to BNC
break out cable CBL-IO-8-BNC.
•DC IN: Connection to external 12V 10A DC power supply.
The Prime camera package includes the PVCAM camera control software library and
drivers needed to use the camera with a variety of third party imaging software. To
obtain the latest version of the library and drivers visit the Photometrics website. The
Photometrics website also contains listings of third party software applications that
support the Prime.
Multiple Cooling Options
Forced Air Cooling
•-10ºC Cooling
•Selectable Fan Speed
Liquid Cooling
• -25ºC Cooling
• Leak-proof, quick-disconnect ports
Dual Interface
High Speed PCI-Express
•100fps
USB 3.0
•31fps
Advanced Triggering Capabilities
Effective Global Shutter
Up to four selectable expose-out lines

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Prime™ sCMOS User Manual
Software
Compatibility
Requirements
Unless there is a preferred version specified by a third party software provider, the latest
version of PVCAM is recommended for use with Prime.
Host Computer
Requirements The host computer (PC) for Prime must meet the following minimum requirements:
•Windows 7/8/10 64-bit operating system
•2.0 GHz or faster Intel processor: either Xeon or Core i7
•8+ GB RAM
•250+ GB serial ATA (SATA) HDD and/or >512 GB solid state drive (SDD)
for high-speed imaging and storage
•512+ MB slot-based ATI/NVIDIA video graphics card (i.e., not an
“onboard/integrated graphics” adapter)
•USB port for use with the USB memory device or Internet access to obtain
the PVCAM library and interface drivers
•USB3.0 port for use with the Prime USB3.0 interface
•An open PCI-Express 4x (4 lane) interface slot or higher for use with the
Prime PCIe interface card
An appropriate Installation Guide is included as an insert with the camera. This guide
provides step-by-step instructions for installing the camera interface software for
Windows-based computers. Additional instructions are included for installing a PCI
Express interface card in the computer.
The Photometrics USB memory device contains the following files:
•Manuals Directory — contains user manuals in PDF format.
•Customer Case Studies — application examples
•Imaging Software – a copy of Open Imaging’s FOSS Application,
Micromanager
•Technical Notes – detailed background on advanced features
•For a 64-bit Windows OS, install PVCam64_Setup_X_X_X_X.exe
•For a 32-bit Windows OS, install PVCam32_Setup_X_X_X_X.exe
•Follow the Installation Guide insert for the version of Windows being used.
Reboot the computer when the installation is complete.
Software
Installation

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Prime™ sCMOS User Manual
Installing the
PCI Express
Interface Card
Because of the data rate resulting from 100fps 2048x2048 imaging with a 16-
bit output, the data rate of the Prime camera is significantly higher than previous
generations of scientific cameras. At 839 MB/s, Prime requires a more powerful
computer interface than previous generations of cameras. For this reason, Prime is
supplied with a high speed PCI Express bridge card that is capable of sustaining the
bandwidth requirements of the camera.
TIP: PCI Express is a high speed peripheral data bus used by the computer to
communicate with video cards, high speed Solid State Drives, and image frame
grabbers. The PCI Express interface card is simply an adapter between the computer’s
internal PCIe bus and the camera.
While this has benefits in cost, reliability, simplicity, and performance, it is important
that the camera is powered on for 10 seconds before starting the PC. This will ensure
that as the computer goes through the boot process, it discovers the camera on the
PCIe bus.
Install the High Speed PCI Express Interface
Note: The model of PCIe card shipped with the camera may differ from the one shown
in the photo.
Warning: Do not use the PCIe interface supplied with the QImaging optiMOS sCMOS
camera with the Photometrics Prime sCMOS camera. While they have a common
cable and connector, they are not compatible.

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Before attempting to operate the camera, first install this interface card into the PC with the
following steps:
1. Shut down the PC
2. Unplug the PC from power mains and ensure the camera is turned off
3. Open the side of the computer to access the PCI and PCIe slots
4. Locate an available 4 channel or higher PCIe slot (marked x4). Refer to the
PC’s documentation to locate a suitable slot.
Tip: The PC may have motherboard slot information on the side cover
5. Holding the Prime PCIe card and (being careful not to touch the board
components or PCIe bridge pins) insert it with the proper orientation into the
open slot. The card should slide into place with minimal resistance and snap
when fully inserted.

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Connecting
Prime to the
PCIe Bus
The Prime sCMOS camera data cable is a quick insertion, quick release cable that works
with the interface card and camera. Either end of the cable can be plugged into either
device, and in any order.
The connector can only be inserted with the correct orientation, do not force the
connector. If the connector does not insert, simply turn the connector over and retry.
Hint: With the camera oriented so the labels on the camera are upright, the green
“quick release” pull tab on the cable will be facing down.
With the cable connected on both ends of the camera, it is ready to power on the
computer.
1. Verify that the power switch on the side of the camera is in the off position.
2. Connect the power supply to the Power connector on the rear of the
camera.
3. Plug the power cord into the power supply and then into a suitable wall
outlet.
4. Switch on the camera (power switch on the side of camera).
5. Wait 10 seconds before powering on the PC
Tip: The power supply and connector used by the Prime sCMOS camera is a common
type. However, Photometrics carefully selects power supplies for optimum noise
performance, EMI compliance and stability. Do not swap power supplies with other
lab equipment even though they may meet the connector, voltage and ampere
requirements of the Prime.

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Connecting
Prime with
USB3.0
Prime’s USB3.0 interface is ubiquitous and easy to use. To use the interface, the PC
must have an open USB3.0 port. Prime is not USB2.0 compatible. USB3.0 ports are
usually indicated by the SuperSpeed+ logo and are typically blue in color.
Tip: USB devices sharing the same bus as Prime contend for available bandwidth,
potentially causing the camera to drop frame rate. For this reason, Photometrics
recommends isolating the camera to its own USB3.0 root hub as shown in the
Windows Device Manager.
A method for creating an independent root hub in computers with many USB devices
is to install a PCI Express based USB3.0 interface card for use with the camera. In this
case Photometrics recommends using the PCIe interface described above, as it also
provides improvements in maximum frame rate.
It is not recommended to connect to Prime external USB3.0 hubs.
Note that the ends of the USB3.0 cable are different between the camera and PC, and
require a specific orientation. The camera has a “Type B” connector and the computer
will have a “Type A” connector. Do not force insertion when connecting the cable – if
significant resistance is encountered stop, reexamine the connection, and if correct,
retry.
With the cable connected on both ends, you are now ready to power on the computer:
1. With the camera off, connect the USB3.0 cable between camera and host
computer.
2. Power the camera on.
3. Wait 30 seconds before launching the application. An LED on the rear of
the camera will stop blinking when the camera is initialized and ready to
communicate.

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Prime™ sCMOS User Manual
Introduction
Scientific CMOS, aka sCMOS, is a recent development in image sensor technology.
The primary advantage provided by sCMOS sensors is high frame rates, even with
very large pixel counts, while still operating with very low electronic noise. This largely
eliminates the speed-resolution-noise tradeoff inherent in CCD sensors.
CMOS Image
Sensor Structure
A major difference between traditional CCD sensors and CMOS sensors is the location
where charge-to-voltage conversion of accumulated photoelectrons takes place. CCD
sensors transfer the pixels accumulated signal in charge packets in “bucket brigade”
fashion across the sensor to a common output node where charge is converted to a
voltage. The voltage is then sampled using off-chip Analog-to-Digital Converters (ADC)
and transferred to the PC as digital grey values.
While providing excellent quantitative photometry and very high image quality, the
large number of transfers and sequential digitization of pixels results in low frame rates.
This speed penalty increases with the number of pixels to be digitized.
CMOS sensors leverage many of the same analog signal concepts used in CCDs, but
places the output node circuitry inside each pixel. This eliminates the charge transfer
process. To read the signal from a given row, the accumulated charge is converted to
a voltage inside the pixel, then each pixel in the row is connected to the appropriate
column voltage bus, where the on-chip ADCs covert the voltages to an 11-bit or 12-
bit grey value. (Thus far, the on-chip ADCs available on CMOS sensors have limited
dynamic range.)
The parallel digitization of all pixels in a row provides CMOS devices with a tremendous
speed advantage. Imagine a CCD with 2048x2048 pixels – and each pixel’s voltage is
measured in 1 usec. To read a single row, 2048 voltage measurements are performed in
serial fashion taking slightly longer than 2 ms, and when repeated for 2048 rows, the
entire image takes over four seconds to be digitized.
On a CMOS device – the entire 2048 voltage conversions needed to digitize a row
happen in parallel. The sensor in the Prime sCMOS camera takes parallelism even
Chapter 3.
Theory of Operation

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Prime™ sCMOS User Manual
further by dividing the sensor into two halves, so that two rows of 2048 pixels can be
measured at the same time. If the time to digitize a pixel remains at 1 us – the time to
read the entire frame is now ~ 1 ms.
In practice, the time saving is split between faster frame rates and slowing the rate of
pixel measurement to reduce electronic noise. For example, if the time to measure a
pixel was increased to 10 usec to lower noise, the image sensor can still be read in 10
ms (for a maximum 100fps).
Of course, there are many challenges to obtaining the same analog performance from
each of the Prime’s four million pixels, whereas a CCD has a single, common output
node resulting in a uniform response. The most common problems are pixel-to-pixel
non uniformity in gain and offset, random telegraph noise (RTN), and defective pixels
with abnormal noise or dark current characteristics (hot pixels).
Often solutions to these challenges are found in the digital domain, where Prime’s
advanced real time signal processing corrects each pixel for gain and offset variation
using calibration at the factory. To address RTN and other pixel defects, real-time digital
filters are used. These corrections are described further in this manual.
Gain Combining
As discussed in the previous section, the column ADCs present in sCMOS devices
have limited dynamic range. This is addressed by making two measurements of the
accumulated charge in each pixel – the first with very high sensitivity but limited to
a maximum signal of approximately 1000 electrons, and the second with reduced
sensitivity but capable of measuring signals up to the pixel’s 30,000 electron full well
capacity.
Combining the two measurements into a single 16-bit value is the function of the digital
“gain combiner”. This mathematical operation is performed on the cameras FPGA. The
result is a single 1x gain of approximately 0.45e/ADU.
In practice, Prime’s advanced FPGA based signal processing does an excellent job of
gain combining as evidenced by the quality of gamma transfer functions (linearity) and
photon transfer functions (signal versus noise). With careful observation and uniform
illumination of the sensor, the zone where two measurements overlap can be seen
as a slight static vertical pattern in the image. This is inherent on all current sCMOS
generation sCMOS cameras. While impacting image quality, these cannot be addressed
without negatively impacting image photometry and wait for further improvements to
the on-sensor ADC conversion.

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Rolling and
Global Shutter
Readout
Rolling Shutter and Global Shutter are the two primary operating modes of CMOS
image sensors. In Global Shutter readout, a global charge clearing mechanism
begins the exposure period for all pixels. Each pixel accumulates signal charge until
the exposure period ends. At this point, the accumulated charge is transferred and
converted to a voltage in the pixels output node, ending the exposure.
The strength of the Global Shutter approach is that all pixels are exposed at the
same instant in time – an important attribute when imaging fast moving objects. The
downside of this approach is the sensor has two phases, an active image accumulation
phase and a subsequent readout phase. As the phases are not overlapped in time, the
maximum achievable frame rate is lower.
In Rolling shutter readout, exposure and readout are overlapped. This is accomplished
by reading one row, while exposing all of the other rows (The row being digitized
“rolls” through the sensor).
For Prime, the time to digitize a single row is 9.6 us, and consequently the delay
between the start of exposure between two adjacent rows is approximately 9.6us.
Digitizing 1024 rows of pixels (the sensor used in Prime digitizes a row in the top and
bottom half of the sensor at the same time), the time delay from the top to the middle
of the sensor is approximately 9.8 ms. Since readout and exposure are overlapped, the
sensor achieves the maximum frame rate of 100fps.
The graphic below depicts the time delay between each row of pixels in a rolling shutter
readout mode with a CMOS camera.
Figure 1: Rolling Shutter Exposure Row by Row Exposure Start/End Offset