Hardware Features
A new flagship for the extensive lineup of Nikon digital cameras, the Digital Eclipse DXM 1200 is Nikon's new high-resolution color digital camera designed exclusively for photography through an optical microscope.
This camera system is one of the most advanced ever produced for digital photomicrography, taking advantage of Nikon's Inter Pixel Stepping (IPS) high-density imaging technology that produces superb images at resolutions up to 12 million (3,840 x 3,072) output pixels. Equipped with high signal-to-noise digital circuit technology, the DXM 1200 enables image capture with exceptionally high sensitivity, resulting in images displaying excellent clarity that rival those taken by an ambient temperature cooled CCD camera. Images captured by the camera can be transferred to the supporting computer via Nikon's proprietary PCI BusMaster interface card (Figure 1) at a rate of 12 frames per second, allowing almost real-time focusing.
In order to support the digital camera system, a Windows-based computer system must be supplied by the user. Nikon recommends a minimum CPU of a Pentium III clocked at 500 MHz or faster. Memory requirements are similar to those of graphics workstations, with a minimum of 256 Mb RAM suggested, but the system can take advantage of up to 1 Gbyte. Computer hard drives are relatively cheap, and the recommendation is a 20-30 Gbyte for drives that store digital images. A PCI expansion slot is required for the interface card, but few computer motherboards are full when shipped from the factory. We recommend the highest-quality video card that the budget will allow, but at least 16 Mb of video ram is strongly suggested. The ACT-1 camera control software was developed for Windows 98 and NT, and will not install on older versions of the operating system. A high-resolution monitor having a display of at least 1024 x 768 pixels at 16.7 million colors is highly recommended. Currently, computers meeting these specifications can be purchased for less than $1000, making this a low-cost, but necessary accessory.
Digital Eclipse DXM 1200 Specifications
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Table 1
Specifications for the Sony ICX085AK CCD utilized in the DXM 1200 and other camera system features are listed in Table 1. The imaging sensor is an two-thirds inch interline-transfer progressive scan chip that supports a high frame readout rate of 30 frames/second. This CCD has a 1360 x 1024 active pixel array producing an 10 millimeter image size using 6.7 x 6.7 micron square pixels masked with a Bayer RGB mosaic filter complement. The chip also features high sensitivity, low dark current, low smear, excellent antiblooming characteristics, and a continuous variable speed shutter. In order to produce images larger than the active pixel array, the CCD is mounted onto a piezo-ceramic electromechanical device that translates the chip in two-thirds pitch pixel steps that produce images having pixel dimensions that exceed those of the CCD.
The interline-transfer CCD incorporates charge transfer channels immediately adjacent to each photodiode so that the accumulated charge can be efficiently and rapidly shifted into the channels after image acquisition has been completed. Interline-transfer CCDs can be electronically shuttered by altering the voltages at the photodiode so that the generated charges are injected into the substrate rather than shifted to the transfer channels. These devices also include an electron "drain" to prevent blooming and are usually equipped with microlens arrays to increase the photodiode fill factor and quantum efficiency.
The camera is mounted onto a microscope by means of a standard C-mount adapter and has an optional 0.63x relay lens that inserts into the microscope camera tube. A shielded interface cable (Figures 1 and 2) is utilized to connect the PCI interface board connector (marked CAMERA on the card external shield) and the connector at the rear of the DXM 1200 camera body. A nylon clamp is wound around the two meter long interface cable, leaving very little slack in the cable, and secured by a clamping screw to the threaded tripod boss to prevent unnecessary movement of the cable. Always check to ensure both the camera and computer are turned off before connecting the two together to avoid electrical damage to any internal components.
The CCD is protected by an optical glass plate that is prone to contamination with dust, lint, fingerprints, and other foreign objects during handling. Prior to mounting the camera on a microscope, make certain that all lenses (both camera and microscope) are clean and free from contamination. Use a soft brush or rubber balloon to remove loose dust. Fingerprints can be removed with a dampened soft and clean cotton cloth, lens tissue, or gauze with absolute alcohol (methyl or ethyl) and wiped clean. Clean the painted DXM 1200 camera body with a mild detergent or silicon-based cleaner--never use solvents such as alcohol, ether, or paint thinner to clean painted, plastic, or printed surfaces. These solvents will damage or discolor finished and painted surfaces and can erase panel markings. Always store the DXM 1200 in a cool, mildew-free environment and protect it from dust and dirt by encasing the body in a plastic bag.
In conclusion, the DXM 1200 digital electronic camera system is a state-of-the-art CCD imaging device that requires careful handling and proper installation of components in both the host computer and microscope. With the proper care, this camera system should provide years of maintenance-free use.