1.4 Megapixel CCD Scientific Cameras for Microscopy

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This fluorescence image of a rat neuron was acquired using one of our 1.4 MP cameras. For more image samples, please see the Applications tab.

Features

• High Quantum Efficiency Maximizes Signal and SNR (60% Peak Quantum Efficiency in
  Monochrome Versions)
• <6 e^- (TEC Cooled) or <7 e^- (Non-Cooled) Read Noise Improves the Threshold of Detectability Under Low Light Conditions
• Software-Selectable 20 MHz or 40 MHz Readout: Maximize Frame Rate (40 MHz) or
  Minimize Noise (20 MHz)
• Asynchronous Reset, Triggered, and Bulb Exposure Modes (See Triggering Tab for Details)
• 2/3" Format, 1392 x 1040 Monochrome or Color CCD Sensor with 6.45 µm Square Pixels
  (Sony ICX285AL or ICX285AQ)
• ThorCam GUI with 32- and 64-Bit Windows^® 7 or 10 Support
• SDK and Programming Interfaces Provide Support for:
  
  • C, C++, C#, Python, and Visual Basic .NET APIs
  • LabVIEW, MATLAB, µManager, and MetaMorph Third-Party Software

Thorlabs' 1.4 megapixel scientific CCD cameras, which offer up to 23 frames per second at 40 MHz readout of the full sensor, are specifically designed for microscopy and other demanding scientific imaging applications. These cameras are ideal for multispectral imaging, fluorescence microscopy, and other techniques that would benefit from high quantum efficiency and low noise.

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1501M-GE Camera Integrated into
60 mm Cage System


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1501M-USB Camera with
MVL25M23 C-Mount Camera Lens

Jason Mills
General Manager,
Thorlabs Scientific Imaging

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Standard Package or Hermetically Sealed TE-Cooled Camera

Our cameras are available in two package styles: a compact, non-cooled standard package and a hermetically sealed package with a two-stage thermoelectric cooler that cools the CCD. The fan-free design minimizes image blur from vibrations. Cooling the camera will reduce the dark current; however, the total dark current is also a function of exposure time. For high light levels requiring short exposure times (less than 1 second), a non-cooled camera is generally sufficient. A cooled camera is recommended for applications with low light levels requiring an exposure greater than 1 second. Please see the Camera Noise tab for more details on the various sources of camera noise and how they impact the choice between a standard and cooled camera.

USB 3.0, Gigabit Ethernet, or Camera Link Industry-Standard Interfaces

Thorlabs' scientific cameras are offered with a choice of USB 3.0, Gigabit Ethernet (GigE), or Camera Link interface. GigE is ideal for situations where the camera must be far from the PC or there are multiple cameras that need to be controlled by the same PC. The GigE and Camera Link cameras are provided with either a GigE or Camera Link frame grabber card and cables. Since USB 3.0 is supported by most computers, the USB cameras do not come with a card, however one is available separately. A power supply and software are supplied with all cameras. More information on what's included is on the Shipping List tab. Your computer must have a free PCI Express slot to install the GigE or Camera Link interface. For more information on the three interface options and recommended computer specifications, please see the Interface tab.

Our cameras have triggering options that enable custom timing and system control; for more details, please see the Triggering tab. External triggering requires a connection to the auxiliary port of the camera. Accessory cables and boards to "break out" the individual signals are available below.

Each camera comes with a user-removable IR filter; for details on the transmission please see the Specs tab. If the filter is removed, it can be replaced with a user-supplied Ø1" (Ø25 mm) filter or another optic up to 4 mm thick; please see the camera manual (found under the red Docs icon below) for details.

The cameras feature standard C-Mount (1.000"-32) threading, and Thorlabs provides a full line of thread-to-thread adapters for compatibility with other thread standards, including the SM1 (1.035"-40) threading used on our Ø1" Lens Tubes. The front face also has 4-40 tapped holes for compatibility with our 60 mm Cage System. Four 1/4"-20 tapped holes, one on each side of the housing, are compatible with our Ø1" posts. These flexible mounting options make Thorlabs' scientific cameras the ideal choice for integrating into home-built imaging systems as well as those based on commercial microscopes.

• The specified performance is valid when using a computer with the recommended specifications listed on the Interface tab.
• Exposure time varies with operating mode; exposure times shorter than 1 ms may be possible when using an external trigger.
• ADC = Analog-to-Digital Converter
• ADU = Analog-to-Digital Unit
• Camera Frame Rate is impacted by the Vertical Hardware Binning parameter. For color cameras, when the Image Type setting in ThorCam is anything other than "Unprocessed" only 1 x 1 binning is available. When set to Unprocessed, the camera can bin up to 24 x 24, but the image produced will be monochrome.
• If your application is read-noise limited, we recommend using the lower CCD pixel clock speed of 20 MHz. For more information about read noise, and for examples of how to calculate the limiting factor of total camera noise, please see the Camera Noise tab.
• For more information on these interface options, please see the Interface tab.

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Click for Raw Data
These curves show the quantum efficiency for the monochrome camera sensor. The NIR Enhanced (Boost) Mode can be selected via the software. The IR blocking filter should also be removed for maximum NIR sensitivity. Please note that the NIR Boost mode will reduce the antiblooming performance. Antiblooming reduces the effect of one overexposed pixel on neighboring pixels.

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These curves show the relative response for the color camera sensor's red, green, and blue pixels.

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Click for Raw Data
The IR blocking filter (Thorlabs' Item # FESH0700) can be removed from the camera; instructions are provided in the manual. If the filter is removed, it can be replaced with a user-supplied Ø1" (Ø25 mm) filter or another optic up to 4 mm thick.

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Non-Cooled Camera

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Hermetically Sealed Cooled Camera

Thorlabs' Scientific-Grade CCD Cameras are ideal for a variety of applications. The photo gallery below contains images acquired with our 1.4 megapixel, 4 megapixel, 8 megapixel, and fast frame rate cameras.

To download some of these images as high-resolution, 16-bit TIFF files, please click here. It may be necessary to use an alternative image viewer to view the 16-bit files. We recommend ImageJ, which is a free download.

Thorlabs' Scientific Camera Applications (Click Images for Details)
Intracellular Dynamics	Brightfield Microscopy	Ophthalmology (NIR)	Fluorescence Microscopy	Multispectral Imaging	Neuroscience	SEM/TEM
Thorlabs' Scientific Camera Recommended for Above Application
1.4 Megapixel Fast Frame Rate	4 Megapixel 8 Megapixel	1.4 Megapixel	4 Megapixel 1.4 Megapixel	4 Megapixel 1.4 Megapixel	1.4 Megapixel	1.4 Megapixel 4 Megapixel Fast Frame Rate

Multispectral Imaging

The video to the right is an example of a multispectral image acquisition using a liquid crystal tunable filter (LCTF) in front of a monochrome camera. With a sample slide exposed to broadband light, the LCTF passes narrow bands of light that are transmitted from the sample. The monochromatic images are captured using a monochrome scientific camera, resulting in a datacube – a stack of spectrally separated two-dimensional images which can be used for quantitative analysis, such as finding ratios or thresholds and spectral unmixing.

In the example shown, a mature capsella bursa-pastoris embryo, also known as Shepherd's-Purse, is rapidly scanned across the 420 nm - 730 nm wavelength range using Thorlabs' KURIOS-WB1 Liquid Crystal Tunable Filter. The images are captured using our 1501M-GE Scientific Camera, which is connected, with the liquid crystal filter, to a Cerna^® Series Microscope. The overall system magnification is 10X. The final stacked/recovered image is shown below.

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Final Stacked/Recovered Image

Thrombosis Studies

Thrombosis is the formation of a blood clot within a blood vessel that will impede the flow of blood in the circulatory system. The videos below are from experimental studies on the large-vessel thrombosis in Mice performed by Dr. Brian Cooley at the Medical College of Wisconsin. Three lasers (532 nm, 594 nm, and 650 nm) were expanded and then focused on a microsurgical field of an exposed surgical site in an anesthenized mouse. A custom 1.4 Megapixel Camera with integrated filter wheel were attached to a Leica Microscope to capture the low-light fluorescence emitted from the surgical site. See the videos below with their associated descriptions for further infromation.

Reference: Cooley BC. In vivo fluorescence imaging of large-vessel thrombosis in mice. Arterioscler Thromb Vasc Biol 31, 1351-1356, 2011. All animal studies were done under protocols approved by the Medical College of Wisconsin Institutional Animal Care and Use Committee.

Camera Back Panel Connector Locations

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1501M-USB, 1501C-USB, 1501M-USB-TE, and 1501C-USB-TE Back Panel Layout

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1501M-GE, 1501C-GE, 1501M-GE-TE, 1501C-GE-TE Back Panel Layout

TSI-IOBOB and TSI-IOBOB2 Break-Out Board Connector Locations

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TSI-IOBOB

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TSI-IOBOB2

TSI-IOBOB and TSI-IOBOB2 Connector	8050-CAB1 Connectors	Camera Auxiliary (AUX) Port
Female 6-Pin Mini Din Female Connector	Male 6-Pin Mini Din Male Connector (TSI-IOBOB end of Cable) Male 12-Pin Hirose Connector (Camera end of Cable)	Female 12-Pin Hirose Connector (Auxiliary Port on Camera)

Auxiliary Connector

The cameras and the break-out boards both feature female connectors; the 8 megapixel cameras have a 12 pin Hirose connector, while the break out boards have a 6-pin Mini-DIN connector. The 8050-CAB1 cable features male connectors on both ends: a 12-pin connector for connecting to the camera and a 6-pin Mini-DIN connector for the break-out boards. Pins 1, 2, 3, 5, and 6 are each connected to the center pin of an SMA connector on the break-out boards, while pin 4 (ground) is connected to each SMA connector housing. To access one of the I/O functions not available with the 8050-CAB1, the user must fabricate a cable using shielded cabling in order for the camera to adhere to CE and FCC compliance; additional details are provided in the camera manual.

USB 3.0 Contents Example

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Item # Shown: 1501M-USB

Gigabit Ethernet Contents Example

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Item # shown: 1501M-GE

Camera Link Contents Example

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Item # Shown: 1501M-CL

Camera Noise and Temperature

Sources of Noise

Noise in a camera image is the aggregate spatial and temporal variation in the measured signal, assuming constant, uniform illumination. There are several components of noise:

• Dark Shot Noise (σ_D): Dark current is a current that flows even when no photons are incident on the camera. It is a thermal phenomenon resulting from electrons spontaneously generated within the silicon chip (valence electrons are thermally excited into the conduction band). The variation in the amount of dark electrons collected during the exposure is the dark shot noise. It is independent of the signal level but is dependent on the temperature of the sensor as shown in Table 1.
• Read Noise (σ_R): This is the noise generated in producing the electronic signal. This results from the sensor design but can also be impacted by the design of the camera electronics. It is independent of signal level and temperature of the sensor, and is larger for faster CCD pixel clock rates.
• Photon Shot Noise (σ_S): This is the statistical noise associated with the arrival of photons at the pixel. Since photon measurement obeys Poisson statistics, the photon shot noise is dependent on the signal level measured. It is independent of sensor temperature.
• Fixed Pattern Noise (σ_F): This is caused by spatial non-uniformities of the pixels and is independent of signal level and temperature of the sensor. Note that fixed pattern noise will be ignored in the discussion below; this is a valid assumption for the CCD cameras sold here but may need to be included for other non-scientific-grade sensors.

Total Effective Noise

The total effective noise per pixel is the quadrature sum of each of the noise sources listed above:

Here, σ_D is the dark shot noise, σ_R is the read noise (typically less than 10 e- for scientific-grade cameras using the ICX285AL CCD; we will assume a value of 10 e- in this tutorial), and σ_S is the photon shot noise. If σ_S>>σ_D and σ_S>>σ_R, then σ_eff is approximately given by the following:

Again, fixed pattern noise is ignored, which is a good approximation for scientific-grade CCDs but may need to be considered for non-scientific-grade sensors.

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Figure 1: Plot of dark shot noise and read noise as a function of exposure for three sensor temperatures. This plot uses logarithmic scales for both axes.The dotted vertical line at 5 s indicates the values calculated as the example in the text.

Dark Shot Noise and Sensor Temperature

As mentioned above, the dark current is a thermal effect and can therefore be reduced by cooling the sensor. Table 1 lists typical dark current values for the Sony ICX285AL CCD sensor used in our 1.4 megapixel monochrome cameras. As the dark current results from spontaneously generated electrons, the dark current is measured by simply "counting" these electrons. Since counting electrons obeys Poisson statistics, the noise associated with the dark current I_D is proportional to the square root of the number of dark electrons that accumulate during the exposure. For a given exposure, the dark shot noise, σ_D, is therefore the square root of the I_D value from Table 1 (for a given sensor temperature) multiplied by the exposure time t in seconds:

Since the dark current decreases with decreasing temperature, the associated noise can be decreased by cooling the camera. For example, assuming an exposure of 5 seconds, the dark shot noise levels for the three sensor temperatures listed in the table are

Figure 1, which is a plot of the dark shot noise as a function of exposure for the three temperatures listed in Table 1, illustrates how the dark shot noise increases with increasing exposure. Figure 1 also includes a plot of the upper limit of the read noise.

If the photon shot noise is significantly larger than the dark shot noise, then cooling provides a negligible benefit in terms of the noise, and our standard package cameras will work well.

Photon Shot Noise

If S is the number of "signal" electrons generated when a photon flux of N photons/second is incident on each pixel of a sensor with a quantum efficiency QE and an exposure duration of t seconds, then

From S, the photon shot noise, σ_S, is given by:

Example Calculations

If we assume that there is a sufficiently high photon flux and quantum efficiency to allow for a signal S of 10,000 e- to accumulate in a pixel with an exposure of 5 seconds, then the estimated shot noise, σ_S, would be the square root of 10,000, or 100 e-. The read noise is 10 e- (independent of exposure time). For an exposure of 5 seconds and sensor temperatures of 25, 0, and -25 °C, the dark shot noise is given in equation (4). The effective noise is:

The signal-to-noise ratio (SNR) is a useful figure of merit for image quality and is estimated as:

From Equation 7, the SNR values for the three sensor temperatures are:

As the example shows, there is a negligible benefit to using a cooled camera compared to a non-cooled camera operating at room temperature, and the photon shot noise is the dominant noise source in this example. In this case our standard package cameras should therefore work quite well.

However, if the light levels were lower such that a 100 second exposure was required to achieve 900 e- per pixel, then the shot noise would be 30 e-. The estimated dark shot noise would be 22.4 e- at 25 °C, while at -20 °C the dark shot noise would be 3.2 e-. The total effective noise would be

From Equation 8, the SNR values are

In this example, the dark shot noise is a more significant contributor to the total noise for the 25 °C sensor than for the -25 °C sensor. Depending on the application's noise budget, a cooled camera may be beneficial.

Figure 2 shows plots of the different noise components, including dark shot noise at three sensor temperatures, as a function of exposure time for three photon fluxes. The plots show that dark shot noise is not a significant contributor to total noise except for low signal (and consequently long exposure) situations. While the photon flux levels used for the calculations are given in the figure, it is not necessary to know the exact photon flux level for your application. Figure 2 suggests a general metric based on exposure time that can be used to determine whether a cooled camera is required if the exposure time can be estimated, and these results are summarized in Table 2. If you find that your dominant source of noise is due to the read noise, then we recommend running the camera at a lower CCD pixel clock rate of 20 MHz, since that will offer a lower read noise.

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(a)

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(b)

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(c)

Figure 2: Noise from all sources as a function of exposure for three different photon fluxes: (a) low, (b) medium, and (c) high. In (c) the signal and photon shot noise saturate above approximately 20 seconds because the pixel becomes saturated at the corresponding incident photon levels. A quantum efficiency of 60% was used for the calculations. Note that these plots use logarithmic scales for both axes.

Other Considerations

Thermoelectric cooling should also be considered for long exposures even where the dark shot noise is not a significant contributor to total noise because cooling also helps to reduce the effects of hot pixels. Hot pixels cause a "star field" pattern that appears under long exposures. Figure 3 shows an example of this star field pattern for images taken using cameras with and without TEC cooling with an exposure of 10 seconds.

(a)

(b)

Figure 3: Images of the "star field" pattern that results from hot pixels using our (a) standard non-cooled camera and (b) our camera cooled to -20 °C. Both images were taken with an exposure of 10 seconds and with a gain of 32 dB (to make the hot pixels more visible). Please note that in order to show the pattern the images displayed here were cropped from the full-resolution 16 bit images. The full size 16 bit images may be downloaded here and viewed with software such as ImageJ, which is a free download.

Thorlabs offers three interface options across our scientific camera product line: USB 3.0, Gigabit Ethernet (GigE), and Camera Link. Once other camera decisions, such as field of view and frame rates, have been made, for many of our camera types it is necessary to choose one of these interfaces. It is important to confirm that the computer system meets or exceeds the recommended requirements listed to the right; otherwise, dropped frames may result, particularly when streaming camera images directly to storage media.

Definitions

• Camera Frame Rate: The number of images per second generated by the camera. It is a function of camera model and user-selected settings. 
• Effective Frame Rate: The number of images per second received by the host computer's camera software. This depends on the limits of the selected interface hardware (chipset), CPU performance, and other devices and software competing for the host computer resources.
• Maximum Bandwidth: The maximum rate (in bits/second or bytes/second) at which data can be reliably transferred over the interface from the camera to the host PC. The maximum bandwidth is a specified performance benchmark of the interface, under the assumption that the host PC is capable of receiving and handling data at that rate. An interface with a higher maximum bandwidth will typically support higher camera frame rates, but the choice of interface does not by itself increase the frame rate of the camera.

USB 3.0

USB 3.0 is a standard interface available on most new PCs, which means that typically no additional hardware is required, and therefore these cameras are not sold with any computer hardware. For users with PCs that do not have a USB 3.0 port, a PCIe card is sold separately below. USB 3.0 supports a speed up to 320 MB/s and cable lengths up to 3 m. Support for multiple cameras is possible using multiple USB 3.0 ports on the PC or a USB 3.0 hub.

Gigabit Ethernet

GigE is ideal for situations requiring longer cable lengths, as well as for systems that require using multiple cameras with one computer. GigE supports a speed up to 100 MB/s and cable lengths up to 100 m. It also uses fairly inexpensive cables, but does require the use of a computer with a GigE card installed. Support for multiple cameras is easily achieved using a Gigabit Ethernet switch. However, the GigE card supplied with the camera is recognized as a public connection to the network; institutions with strict policies only allow registered devices and trusted connections. For any questions regarding using our GigE card at your institution, please contact your IT department.

Camera Link

Camera Link is ideal for applications requiring very high data transfer rates of up to 850 MB/s. However, the maximum cable length is 10 m. Camera Link requires the use of the supplied Camera Link card and cables for connecting to a computer. To operate our 4 and 8 megapixel cameras in quad-tap mode a second Camera Link connection is required.

Scientific Camera Interface Summary

Interface	USB 3.0	Gigabit Ethernet	Camera Link
Interface Image (Click to Enlarge)
Maximum Cable Length	3 m	100 m	10 m
Maximum Bandwidtha	320 MB/s	100 MB/s	850 MB/s
Support for Multiple Cameras	Via Multiple USB 3.0 Ports or Hub	Via Switch Topology (Click for Details)b	No
Available Cameras	200 Frames per Second Scientific-Grade CCD Cameras 1.4 Megapixel Scientific-Grade CCD Cameras 4 Megapixel Scientific-Grade CCD Cameras 8 Megapixel Scientific-Grade CCD Cameras

• Performance will vary depending on the exact PC configuration.
• Up to 4 cameras have been tested in the GigE switch topology.

Triggered Camera Operation

Our scientific cameras have three externally triggered operating modes: streaming overlapped exposure, asynchronous triggered acquisition, and bulb exposure driven by an externally generated trigger pulse. The trigger modes operate independently of the readout (e.g., 20 or 40 MHz; binning) settings as well as gain and offset. Figures 1 through 3 show the timing diagrams for these trigger modes, assuming an active low external TTL trigger.

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Figure 1: Streaming overlapped exposure mode. When the external trigger goes low, the exposure begins, and continues for the software-selected exposure time, followed by the readout. This sequence then repeats at the set time interval. Subsequent external triggers are ignored until the camera operation is halted.

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Figure 2: Asynchronous triggered acquisition mode. When the external trigger signal goes low, an exposure begins for the preset time, and then the exposure is read out of the camera. During the readout time, the external trigger is ignored.  Once a single readout is complete, the camera will begin the next exposure only when the external trigger signal goes low.

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Figure 3: Bulb exposure mode. The exposure begins when the external trigger signal goes low and ends when the external trigger signal goes high. Trigger signals during camera readout are ignored.

Figure 4: The ThorCam Camera Settings window. The red and blue highlighted regions indicate the trigger settings as described in the text.

External triggering enables these cameras to be easily integrated into systems that require the camera to be synchronized to external events. The Strobe Output goes high to indicate exposure; the strobe signal may be used in designing a system to synchronize external devices to the camera exposure. External triggering requires a connection to the auxiliary port of the camera. We offer the 8050-CAB1 auxiliary cable as an optional accessory. Two options are provided to "break out" individual signals. The TSI-IOBOB provides SMA connectors for each individual signal. Alternately, the TSI-IOBOB2 also provides the SMA connectors with the added functionality of a shield for Arduino boards that allows control of other peripheral equipment. More details on these three optional accessories are provided below.

Trigger settings are adjusted using the ThorCam software. Figure 4 shows the Camera Settings window, with the trigger settings highlighted with red and blue squares. Settings can be adjusted as follows:

• "HW Trigger" (Red Highlight) Set to "None": The camera will simply acquire the number of frames in the "Frames per Trigger" box when the capture button is pressed in ThorCam.
• "HW Trigger" Set to "Standard": There are Two Possible Scenarios:
  • "Frames per Trigger" (Blue Highlight) Set to Zero or >1: The camera will operate in streaming overlapped exposure mode (Figure 1).
  • "Frames per Trigger" Set to 1: Then the camera will operate in asynchronous triggered acquisition mode (Figure 2).
• "HW Trigger" Set to "Bulb (PDX) Mode": The camera will operate in bulb exposure mode, also known as Pulse Driven Exposure (PDX) mode (Figure 3).

In addition, the polarity of the trigger can be set to "On High" (exposure begins on the rising edge) or "On Low" (exposure begins on the falling edge) in the "HW Trigger Polarity" box (highlighted in red in Figure 4).

Example Camera Triggering Configuration using Scientific Camera Accessories

Figure 5: A schematic showing a system using the TSI-IOBOB2 to facilitate system integration and control. 

As an example of how camera triggering can be integrated into system control is shown in Figure 5. In the schematic, the camera is connected to the TSI-IOBOB2 break-out board / shield for Arduino using a 8050-CAB1 cable. The pins on the shield can be used to deliver signals to simultaneously control other peripheral devices, such as light sources, shutters, or motion control devices. Once the control program is written to the Arduino board, the USB connection to the host PC can be removed, allowing for a stand-alone system control platform; alternately, the USB connection can be left in place to allow for two-way communication between the Arduino and the PC. Configuring the external trigger mode is done using ThorCam as described above.

About Thorlabs Scientific Imaging

Thorlabs Scientific Imaging (TSI) is a multi-disciplinary team dedicated to solving the most challenging imaging problems. We design and manufacture low-noise, high performance scientific cameras, interface devices, and software at our facility in Austin, Texas. In addition, we are leveraging the engineering experience across Thorlabs, a vertically integrated photonics products manufacturer, to bring to market a line of integrated imaging systems, including our forthcoming, patent-pending system for whole-slide scanning.

A Message from TSI's General Manager

As a researcher, you are accustomed to solving difficult problems but may be frustrated by the inadequacy of the available instrumentation and tools. The product development team at Thorlabs Scientific Imaging is continually looking for new challenges to push the boundaries of Scientific Cameras using various sensor technologies. We welcome your input in order to leverage our team of senior research and development engineers to help meet your advanced imaging needs.

Thorlabs' purpose is to support advances in research through our product offerings. Your input will help us steer the direction of our scientific camera product line to support these advances. If you have a challenging application that requires a more advanced scientific camera than is currently available, I would be excited to hear from you.

Sincerely,

Jason Mills
General Manager
Thorlabs Scientific Imaging