Imaging using Gatan Cameras

Why are the cameras called DualVision?

DualVision refers to a family of cameras that can provide image output in both digital and video (analog) format.

What do "300W" and "600" stand for?

The numbers 300 and 600 represent the effective CCD size. In general, for a given number of CCD pixels, the larger the effective CCD size, the higher the resolution. "W" indicates that the camera is mounted in the wide angle (35mm) position of the TEM.

Is DualVision CCD a digital camera?

Yes. The data depth is 12-bit, i.e. 4096 intensity levels.

What is the pixel resolution of DualVision?

The DV 300W is 1300 x 1030 pixels and the DV 600 is 1024 x 1024.

What is the TEM operating voltage?

DV 300W can be operated up to 200kV and DV 600 up to 300kV/400kV with additional lead shield.

What is the computer platform?

DualVision is currently supported on Windows 98 and NT. As of January 2001, DualVision will be supported on Windows 2000. There is no Macintosh support.

What is the advantage of using Windows 98 over Windows NT?

There is really no advantage of using one over the other. The only reason we recommend Windows 98 is that the Dazzle frame grabber only supports Windows 98. We are currently testing a new generation of Dazzle on Windows 2000.

What is the field of view?

Due to the mounting position, the field of view is very different for DV300W and DV600. The former has a field of view 60% larger than the film, and the latter only 10% of the film.

What is the effective magnification on the camera?

The effective magnification for DV300W is about 10% of the instrumental magnification (indicated on the TEM panel), and 80% for DV600.

Can I use DualVision 300W to capture high resolution lattice images?

No. The camera is not designed for high resolution imaging purpose. The reason is simply due to the fact that this camera is mounted in the 35mm port of a TEM column. The effective magnification on the CCD is only 10% of the instrumental magnification. To image graphite fringes (0.34nm), one would need a magnification over 1,000,000x.

What is the main difference between the DualVision and the MultiScan™ cameras?

The main difference is the CCD sensor. MultiScan uses a traditional CCD sensor called a full-frame CCD. It is necessary to use a beam shutter during data readout. DualVision uses a CCD operating at a higher speed that eliminates the need for a shutter. Furthermore, DualVision cameras do not need cooling water connection, which makes the installation simpler.

What are the unique features of DualVision?

There are three unique features of the DualVision cameras: (1) they have both digital and video output; (2) camera rotation about the sensor axis; and (3) excellent anti-blooming design (essential for electron diffraction work).

What are the suitable TEM applications?

The DualVision cameras are designed to meet the needs of a broad range of TEM applications in both life and materials science such as pathology, anatomy, cells and tissues, intercellular structures, pharmaceutical industry, etc. and metals, ceramic, semiconductor industry, nano-phase materials, oxide, etc.

Are DualVision cameras cooled?

Yes. They are both cooled to a moderate temperature (about +15°C) by using a thermoelectric cooling method.

How many ports are needed for DualVision 300W?

Two ports, one for the CCD camera's optical assembly and other one for retractable prism.

Since there is no TEM shutter required, how is the dark subtraction procedure carried out?

DV 300W has a built-in internal shutter in its CCD electronics. DV 600 uses dark current parameterization technique to subtract the dark current.

Does Gatan TEM Tune and DigitalMontage™ software work with DualVision cameras?

Yes, both software packages work with DualVision cameras. The only requirement is the availability of a functional RS232 serial interface (except Tecnai and FasTEM).

How stable is the gain reference image of DualVision 300W when the camera is inserted and retracted?

The gain reference image is quite stable for extended period of use. The retraction and insertion have sub-pixel accuracy. The retraction mechanism is based on Gatan patented technique that was previously used in the AccuView CCD camera.

Do I have to prepare a new gain reference image when rotating the DualVision cameras?

Yes, you do for the DV 300W. No, you do not for the DV 600. For DV300W, the scintillator and CCD are independent in their positions, so when rotation occurs, a new correspondence between the scintillator and the CCD pixel must be re-established. For DV600, the scintillator and the CCD remain a rigid body assembly, so camera rotation does not alter the relationship between the scintillator and the CCD.

What is the format of video output?

Industry standard EIA (525 line) or CCIR (625 line).

What is the video frame rate?

15 frames per second.

What is the video image resolution in the MPEG movie clip?

The resolution is about 320 x 240 pixels, but can be up to 640 x 480 pixels.

What is the time resolution in MPEG movie?

The camera outputs video signal at a rate of 15 fps even the standard video rate is 30 fps (525 line) or 25 fps (625 line). So the limiting rate is 15 fps. Therefore the time resolution is 1/15 sec.

In recording in-situ experiments, how long can I record my MPEG movie?

You can record experiments as long as you like provided you have enough space on your hard disk.

How much memory does MPEG movie require?

It depends on the quality of the MPEG movie. For the highest quality, it takes about 23MB per minute and for the normal presentation quality, it takes about 15 MB per minute.

What is the difference between "Start Imaging" and "Start Diffraction" in the video option?

The only difference is the exposure time for the CCD. "Start Diffraction" uses a slightly longer exposure to improve the image quality.

Is the video image gain normalized?

No.

Should I be worried about the possible damage to the scintillator when viewing or recording diffraction patterns with the DualVision cameras?

You do not need to worry about damaging the scintillator, but care should be taken. Just like treating the TEM viewing screen, you should not leave a focused intense electron beam or electron diffraction pattern on the scintillator unattended. Whenever possible, use reduced beam current on the sample and SAD aperture when imaging diffraction patterns.

Can DualVision 600 replace 622 TV camera?

622 TV has a higher DQE than DV600. This means 622 is more sensitive than the DV600. Under high resolution imaging conditions, where electron dose on sample is limited, 622 has the advantage in image detection over the DV600.

Are DualVision cameras embedded on Tecnai microscopes?

Yes, they have been tested on Tecnai microscope and have passed the test.

Does DualVision use Gatan's FireWire to acquire image data?

No. DualVision cameras use a PCI DMA card from Roper Scientific Instruments to acquire the image data.

Can I do Live FFT?

Yes, you can do Live FFT with either camera.

Can I use DualVision cameras to study beam sensitive samples?

This is not recommended. DualVision cameras are designed for their image quality, not their sensitivity. To study beam sensitive samples, use Gatan MultiScan™ CCD cameras.

Can I trade-in my old Gatan AccuView camera for DualVision 300W?

Yes, you can. Please contact your Gatan sales representative for details.

Can I use my own computer to control the DualVision cameras?

This is not recommended. Any range of problems might occur from using a computer that is not fully tested. We strongly recommend you buy the entire camera package and leave the risk to us. Please contact your Gatan sales representative for ordering instructions.

If I have a DualVision 300W and a bottom mount MultiScan, can I use DigitalMicrograph to control both cameras?

Yes.

Can I mount DualVision 300W camera at the bottom of my TEM?

No. We have other cameras for you to choose from. Please contact your Gatan sales representative for details.

What is MultiScan?

MultiScan is the Gatan family of cameras formerly referred to as "794 MSC". The name changed because of Gatan's wish to classify its CCD cameras on a consistent basis. The chosen criterion is the effective CCD area since the resolution of a CCD camera is not only determined by the total numbers of CCD pixels, but also the size of each CCD pixel. So the CCD area is a natural measure for ranking the camera resolution. The CCD area is normalized to "squared millimeter".

What does "600" stand for?

It stands for 600 mm².

What does "W", "CW", "HP" all stand for?

"W" stands for Wide-angle. "C" stands for Cooling. These refer to 35mm port cameras. "HP" stands for High Performance. This camera is bottom mount and compatible with GIF or ENFINA system by virtue of retractability.

What is the pixel resolution of MultiScan cameras?

1024 x 1024 pixels and each pixel is 24mm x 24mm.

What are the TEM operating voltages for the MultiScan cameras?

Up to 200kV for MS600W and MS600CW. Up to 400kV for MS600HP.

What is the recommended computer platform?

MultiScan cameras are only supported by Windows 2000.

How does MultiScan differ from SlowScan (SSC) cameras?

SlowScan (SSC) cameras are the first generation CCD cameras that Gatan made. The main difference is that (1) the image data from the MultiScan cameras can be read out at different speeds; and (2) Anti-blooming (beneficial to recording electron diffraction pattern).

What is the field of view?

The field of view of MS600W and MS600CW is about 6 times larger than the standard film at the same TEM magnification. MS600HP has a field of view of about 10% of that of film. For more details, please see Gatan MultiScan brochure.

What is the effective magnification on the camera?

With reference to the TEM displayed magnification, the effective magnification on the CCD camera is about 20-30% for MS600W and MS600CW and 130-150% for MS600HP.

If I want to record high-resolution lattice images, which camera should I choose?

Since lattice fringes can only be resolved at high magnifications, the suitable CCD camera would be the MS600HP since it can easily achieve the high magnifications required.

What is the main difference between the MultiScan™ and the DualVision™ cameras?

The main difference is that MultiScan cameras do not have video output. Only digital data is available from MultiScan cameras.

What are the unique features of the MultiScan when compared with DualVision cameras?

(1) 1:1 fiber-optical coupling (good for both resolution and sensitivity); (2) Choice of YAG scintillator for MS600CW and MS600HP.

How should I choose the right MultiScan camera for my application?

The MS600W and MS600CW cameras are designed for general life science applications while the MS600HP is designed for general materials science applications and biological applications such as molecular structural biology that demand sub-nanometer image resolution.

Are MultiScan cameras cooled?

Both MS600CW and MS600HP are peltier cooled (to ±30°C). The MS600W is not cooled.

How many ports are needed for MultiScan 600W and 600CW?

Only one 35mm port is needed on the TEM.

What are the requirements for MultiScan camera installation?

(1) TEM beam shutter for image readout; (2) water for cooling CCD (except MS600W); and (3) air for camera insertion and retraction.

What optional software is recommended for MultiScan cameras?

For MS600W and MS600CW: TEM AutoTune and DigitalMontage. For MS600HP: TEM Tune, HREM AutoTune, DigitalMontage, HoloWorks, DIFPACK.

What is the difference between a grade A and a grade B CCD?

The difference is the number of column defect allowed in the CCD sensor. For a grade A CCD, there is no column defect in the central 750 x 750 CCD area. For a grade B CCD, the maximum number of column defects should not exceed 10 in the whole image.

What is a column defect and will it affect my images?

The column defect refers to the CCD pixels that line up in a column and a yield significantly lower charge output (50% or more) than a normal column. The intensity of a column defect can be easily corrected (automatically) by using the intensity values from adjacent normal columns (mathematical interpolation algorithm). It is invisible to the eyes and therefore does not affect images in general.

When does the effect of "column defect" become significant?

As explained above, the intensity value for the "column defect" is derived from the two adjacent normal columns. So it introduces a very subtle difference, which is usually negligible. However, when an application requires continuous image data (such as continuous phase information in holography), grade A CCD should be considered.

How should I make recommendations on CCD grade?

As explained above, the difference between grade A and B is very subtle. Aside from the nature of the applications, if the budget is not a concern, offer grade A.

What is the difference between phosphor and YAG scintillators?

Phosphor generates more photons (light signal) than YAG, but the photon generation is more uniform (less noise) for YAG than phosphor. Phosphor is typically offered for applications that require more sensitivity (such as low dose on beam sensitive specimens). YAG is typically offered for photographic image quality. Please note that YAG is not available for TEM voltages above 200kV.

What is the dynamic range of a CCD camera?

The dynamic range can be considered to be the effective intensity levels in an image.

What is the benefit of 14-bit dynamic range vs. 12-bit?

The higher dynamic range offers the following advantages: (1) better representation of intensity levels in an image; (2) ability to record strong and weak intensities in a single image (such as a diffraction pattern). The higher dynamic range is also beneficial in performing image processing.

What is the best TV camera to recommend for a bottom mount MSC camera?

If there is no GIF or ENFINA spectrometer attached to the TEM, the best TV camera that works well with the MS600HP (bottom mount) is the 622.SC. Otherwise, the 676 GIF compatible TV camera is the only choice. The 692 retractable TV should work with the MS600HP, but this TV camera is not intensified; therefore is not as sensitive as 622.SC and 676.

What is the difference between 1k x 1k and 2k x 2k CCD cameras?

The 2k x 2k CCD camera has an area more than 6 times that of the 1k x 1k MultiScan camera. The pixel size is 25% larger for the 2k x 2k camera, which results in better image resolution.

Can MSC cameras output video images?

No. Only digital data is recorded from the MultiScan cameras.

What is the benefit of cooling the CCD camera?

To reduce the dark noise in the CCD. The dark noise refers to the charges in CCD pixels when there is no electron striking the CCD scintillator. The dark noise is generated by a thermal process. Reducing the dark noise can effectively extend the dynamic range of the CCD camera.

What is the benefit of installing a bottom mount CCD camera before the GIF or ENFINA system?

It is much easier to record unfiltered TEM images with the MS600HP camera. The user does not have to worry about adjusting GIF or ENFINA settings?. Moreover, it is more straightforward for the user to record images with the MS600HP. In other words, what you see on the TEM viewing screen is basically what you get with the CCD camera.

Can MultiScan cameras replace film?

Yes. The CCD has shown advantages in sensitivity, linearity, superior dynamic range, and with no image distortion. The main disadvantage for CCD is the lack of image pixels (film has 20-30 million pixels while 1k x 1k CCD only has 1 million pixels). However via DigitalMontage, one can obtain digital images larger than the film size. Therefore, in the general sense, MultiScan cameras can replace film. Please note that in special TEM applications such as molecular structural biology, the use of film is still preferred when considering image resolution, beam dose, and field of view. I need to purchase a CCD camera for electron holography applications.

Should I consider a 1k x 1k or 2k x 2k CCD camera?

For holography applications, a 2k x 2k CCD camera is preferred. This is because the reconstruction of an electron hologram only uses roughly 1/4 of the image area. For a 1k x 1k camera, this means only 256 x 256 pixels. For 2k x 2k camera, the reconstruction can be as large as 512 x 512 pixels.

Why is there mismatch in the montage image acquired from wide-angle MultiScan CCD cameras?

It is common to observe mismatch in montage images acquired from a wide-angle CCD camera. The mismatch comes from the common distortions in a TEM column when large-field-of-view images are acquired. Such distortions increase rapidly as the third power to the radial distance. Typically the distortion is less than 1% at the edge of the film. Since the Gatan wide-angle CCD camera has a field of view much larger than film (6 times more), it is inevitable to observe distortions from the TEM. Therefore, the mismatch is not an indication of poor software quality.

What are the main differences between the wide-angle and bottom mount MultiScan CCD cameras?

Field of view and effective magnifications. Wide-angle cameras have a large field of view (about 6 times larger than that of film), but have an effective magnification of 20-30% of that of film. On the other hand, a bottom mount camera has a field of view of only 10%, but effective magnification of about 130-150% of that of film.

Do MultiScan cameras use IEEE 1394 (FireWire™) to acquire image data?

Yes. All MultiScan cameras are tested with the industry standard IEEE 1394 hardware interface on Windows 2000.

Can I do Live FFT with MultiScan cameras?

Yes.

Can I do TEM Tuning and DigitalMontage with MultiScan CCD cameras?

Yes, absolutely. However, mismatch may be observed in montage images acquired from wide-angle cameras, i.e. MS600W and MS600CW.

If I have an SSC camera, 694 or 689, can I upgrade the camera to Windows 2000 platform and IEEE 1394 interface?

No. Gatan does not offer any sort of upgrade. The hardware components have changed so much in the past, it is almost impossible to upgrade them to the current platform. Gatan recommends a trade-in option for the SSC cameras.

Can I purchase my own PC computer to control the MultiScan camera?

Yes, you can. Please consult your Gatan sales representative for recommended computer specification. Please note that computers not recommended by Gatan are not guaranteed to work with the MultiScan cameras.

If I have a DualVision 300W and a bottom mount MultiScan 600HP, can I use DigitalMicrograph to control both cameras?

Yes, you can with the Gatan Microscopy Suite 2000 software.