LV-Series Cameras

Based on our flagship DE-Series cameras for electron microscopy, we have extended direct detection technology for low voltage electron microscopy. Just as biological cryo-EM was revolutionized several years ago by direct detectors, low voltage EM (such as LEEM/PEEM) are now on the cusp of a similar revolution. Achieve results you never before thought possible…

Introduction

2010 Microscopy Today Innovation AwardWith the goal of propelling electron microscopy to new frontiers, Direct Electron introduced the first large-format Direct Detection Device (DDD®) in 2008, as the culmination of academic and industrial partnerships working through many generations of sensor development beginning in 2001. As the pioneer in direct electron detection, our revolutionary DDD sensors were recognized with the 2010 Microscopy Today Innovation Award.

Principle of Direct Detection

Traditional low-energy electron detectors use a microchannel plate (MCP) to multiply the incident primary electrons. The resulting cloud of electrons from the MCP then travels to a phosphor scintillator which converts these electrons to photons, which can be detected by the CCD imaging sensor. Resolution is degraded in several of these steps, including the electron multiplication in the MCP, the conversion to photons in the scintillator, and the transfer from the scintillator to the CCD detector.

In contrast, our DDD directly detects image-forming electrons in the microscope without the use of a MCP or a scintillator. The result is dramatically better resolution, signal-to-noise ratio, and sensitivity.

Principle of Direct Detection

The secret to the DDD’s high performance is its thin sensing layer. Incident beam electrons pass through this thin layer leaving an ionization trail that is collected and either integrated or counted in pixels. Because the layer is so thin, lateral charge spread is minimized resulting in higher resolution than other detectors. Furthermore, image distortions are minimized since the DDD directly detects electrons without having to transfer signal through fiber-optic or optical lenses.

A second innovative feature of the DDD is its high frame rate, with no dead time between frames. This high frame rate delivers intrinsic dose fractionation during image acquisition, which can be exploited for motion correction, damage compensation, and other image processing techniques. High frame rate data acquisition also enables challenging applications such as in situ TEM.

Performance

Compared to the conventional detector for low-voltage EM (microchannel plates + CCD), the LV-126 delivers significantly better resolution. This boost in resolution not only significantly improves image quality, but it also allows users to collect images at lower magnification in order to dramatically increase the field-of-view. Indeed, at constant resolution, the LV-126 delivers approximately 8x more information than a conventional low-voltage EM detector.

Comparison of LV-126 to Microchannel Plates + CCD

Comparison between the Direct Electron LV-126 (left) and traditional channel plates + CCD (right). The images show cropped images of graphene layers on copper substrate, collected in PEEM mode. The bias voltage was selected so that the monolayer of graphene appears bright while the bilayers appear dark. Courtesy of Rudolf Tromp, IBM.

LV-126 Average Resolution

Image of graphene on SiC collected on the LV-126 with LEEM. The average resolution was measured to be Average resolution : 5 ± 0.5 pixels (30 ± 3 μm). Therefore, there are approximately 800 resolution elements across the total field-of-view for the LV-126 (4096×3072), compared to only 280 resolution elements across the field-of-view of a conventional CCD with microchannel plates. Courtesy of Rudolf Tromp, IBM.

 

Camera Operation Modes

Images of the edge of a beamstop collected on a DE-20 camera at 300 kV in integrating counting modes.

Integrating and Counting Modes

The high speed and ultra high single-electron sensitivity of direct detection cameras enable two different modes of operation:

  • Integrating mode – The total signal deposited on the detector by each electron is summed to form the final image. Due to its versatility and speed, this is the most popular mode of operation for a wide range of applications.
  • Counting mode – Each incident electron is individually detected, isolated, and localized. In this mode, every incident electron is consistently represented by a single count in a single pixel (or sub-pixel). While this mode represents the highest possible performance, it is only effective in very low dose applications.

Our LV-Series Cameras allow users the choice between either integrating or counting mode.

Compatibility

Our LV-Series cameras are high vacuum compatible and our engineers can work with you to accommodate many different mechanical interfaces. Please CONTACT US for more information about your specific instrument.

Currently Available LV-Series Cameras

As a result of our continuing development, we are proud to offer a range of direct detection cameras to the TEM field. Reflecting our focus on empowering users for a broad range of experiments, all of these cameras deliver the flexibility and versatility that a modern TEM facility demands. However, the features and specifications of each of these cameras are optimized for certain applications, to push your productivity to its limit.

For more information, please click the name of each camera below, or CONTACT US.

CameraLV-126
DDD Generation8
Pixel Size (μm)6.0
Array Size (Pixels)4096 × 3072
Megapixels12.6
Maximum Frame Rate with Full Array40 fps (bin 1×)
75 fps (bin 2×)
Integrated Survey SensorNone
Detection Energy Range10 - 40 keV
Typical ApplicationsLEEM/PEEM; low voltage electron microscopy