Nikon's Eclipse E800 biological research microscope was a versatile, ergonomically designed instrument that was one of the first models equipped with the revolutionary CFI60optical system designed to ensure bright, sharp, crisp, and aberration-free images in all applications.
Since its introduction in 1996, this research-level microscope has helped to set the standard for fluorescence imaging, low magnification brightfield, and other advanced applications. Building upon the success of the popular CFI60 optical system (60-millimeter parfocal distance and 25-millimeter objective thread size) first installed on the Eclipse E600, Nikon has moved a step further by introducing ultra-low magnification objectives and has increased the standard field of view to 25+ millimeters. Introduced with the Eclipse E800 was a plan 0.5x magnification objective, which accommodates a 50-millimeter field of view at the unprecedented magnification of 0.5x. When coupled with a 2x projection lens, the 0.5x objective permits macrophotography at 1:1 magnification (in effect, actual size documentation). The new macro objective lens is particularly useful for investigating large specimens such as brain slices, developing embryos, and extensive tissue sections. This objective is easily accommodated into the microscope without major re-configuration, and is interchangeable with other objectives on a standard rotating nosepiece.
Like the workhorse Eclipse E600, the E800 optical system features a tube lens focal length of 200 millimeters and advanced universal objectives for multiple observation techniques, including brightfield, darkfield, differential interference contrast (DIC), epi-fluorescence and phase contrast. Advances in optical design eliminate the need to change objectives in order to optimize contrast enhancing filters, annuli, or prisms while maintaining the same optical quality as dedicated lenses. The exceedingly long working distances, coupled with high numerical apertures of Nikon's CFI60 optics, allow microscopists to more easily handle even relatively thick specimens, provide superior resolution, and offer improved image capability with the elimination of optical aberrations. Axial and lateral chromatic aberrations are both corrected in the objective and tube lens, producing sharp, aberration-free images that are devoid of color fringing and distortion at the viewfield periphery.
An advancement over earlier research microscope frames and optical systems, the Eclipse E800 is truly modular with a choice of 10 types of condensers: darkfield (oil or dry), universal (oil or dry), phase contrast, swing-out, achromat/aplanat, long working distance achromat, low power and macro condensers. With the universal condenser turret, the microscopist may select phase contrast, DIC or darkfield condenser modules without stopping to change the condenser.
The E800 is outfitted with a base-mounted diascopic illuminator that uses a 12-volt 100-watt tungsten-halide lamp inside a pre-centered or centering lamphouse with an external power supply. To deliver a higher degree of brightness, episcopic vertical illumination is available with a 12-volt 100-watt xenon or mercury arc lamphouse powered by the built-in starter in the optional epi-fluorescence module. There is a choice of sextuple nosepiece or sextuple DIC nosepiece and detachable stages and substages.
By increasing the length of the parallel light optical path, the Eclipse E800's design accommodates the use of three levels of modules (i.e., epi-fluorescence, macro slider, and accessory modules) without significantly sacrificing optical performance. This is quite an advance in versatility from earlier modular frames that at first did not accommodate any other intermediate tubes when the epi-fluorescence module was in use and later with the E600, allowed one additional intermediate module. The Eclipse E800 was one of the first modular microscopes that can realistically perform at a research level from one frame for a broad range of fluorescence applications, such as video-enhanced contrast (VEC), fluorescence in-situ hybridization (FISH) and laser confocal microscopy, as well as other microscopy applications, coming closer to E. Leitz Wetzlar's ideal for the "universal" microscope. Limitations beyond the 200 millimeter tube lens focal length, the optimum derived by the optics designers, are in part, based on a realistic height of the microscope and comfortable viewing.
Nikon's engineers, moving beyond the improved optics, accentuated the modularity and ergonomics of this advanced biological research microscope using computer-assisted engineering. Thorough design analyses resulted in greater strength and rigidity throughout the microscope. The wide base and arm and super-rigid structure ensure stable image acquisition at high magnifications, that is unaffected by the added load of mounted accessories including heavy cameras. The Eclipse E800 can accommodate large-sized accessories, up to five times the load of conventional microscope stands.
Predicting fluorescence microscopists as the largest user-group, the designers of the Eclipse E800 favored these applications in both function and utility. Epi-illumination is beamed through an improved epi-fluorescence collector lens (corrected for entire visible spectrum with even illumination), the field diaphragm, the optional aperture diaphragm, and the applicable filter block housed in the epi-fluorescence module. The expanded linear slider for the E800 microscope handles up to five filter blocks (in contrast to the previous standard of four blocks): one multi-band filter, three corresponding single-band filters, and with one additional filter or the slider position is set aside for brightfield microscopy. The three neutral density filters in the epi-fluorescence module are replaceable with excitation filters making possible dual excitation applications without moving the filter blocks. The new designs of the shutter control and short-stroke slider lever permit quick, accurate switching of filters and touch recognition, even when operated from a darkroom.
Just as the objectives and condensers are matched in the optical system, the epi-fluorescence filter cubes or blocks are organized by application and excitation method for easier selection. Designation labels at the front of the epi-fluorescence attachment aid the microscopist in recognizing the current filter positions in the slider and their filter specifications. Six sets of single filters (ultraviolet, violet, blue-violet, blue, green, and yellow excitation methods), long-pass and band-pass green fluorescent protein (GFP) filters, three sets of dual filters, and two sets of triple filters complement the wide array of available objectives and condensers for the E800 for more than 27 different epi-fluorescent applications including serotonin, quinacrine, acridine orange, rhodamine and others.
The ergonomic design of the E800 allows the user to add accessory modules without changing the eye level. The main control knobs and handles can be operated with just a slight movement of the hand, reducing the risk of strain and stress from repeated motion over long periods of usage. Control knobs for focusing and moving the stage are located equidistant from the operator, eliminating the need to twist the body to reach both controls. A novel approach at the time of the E800 microscope introduction allows one-handed operation of both the stage and fine focus. The eyepiece tube is set at a 20-degree angle, a departure from the 25 degrees of the E600 eyepiece, which is claimed to be a more natural and comfortable viewing angle (based on microscopist field surveys). A tilting, variable eyepiece tube, which adjusts from 10 to 30 degrees, was also available as an option for custom fitting the microscope for multiple observers. Additionally, microscopists with deep eye sockets or narrow interpupillary distances may prefer the E800, since the interpupillary adjustment range is significantly enlarged and the diameter of the eyepiece lens reduced.
The low-profile stage has extended stage travel for movement and is centerable and rotatable. The space between the microscope arm and stage is greatly enlarged compared with conventional microscope bodies, facilitating nosepiece rotation and the use of objective correction collars. Coupled with the CFI60 objective's long working distance, specimen handling and micromanipulation on the E800 is made much easier.
The fully automatic photo system head can send 100 percent of the light from the objective to the observation port, metering sensor, film plane and TV (digital camera) port, ensuring a sharp, high contrast image at faster shutter speeds, even with dark specimens. The unique automatic finder system makes the photo system head easy to use. In bright field or low light fluorescence situations, the system automatically detects if the operator has moved away from the binocular viewing port and closes the finder shutter. Multi-sensor 0.1 percent and 1 percent spot, 35 percent average metering, and two program scanning spot metering modes make this photomicrography system better adapted for epi-fluorescence. Switching the optical path from one camera to another is a one-touch operation. Controls, such as the 4x magnifier selector, optical path changeover levers, and metering mode switching, are all concentrated together for quick access and speedy operation.
The U-III photomicrographic system featured an advanced exposure system with a multi-point sensor, performing quick, precise exposure settings. The optional cooled charged-coupled devices (CCD), CCTV camera, and video enhanced contrast (VEC) systems provide the microscopist with a wide choice of direct recording and flexible image processing for the Eclipse E800.
Nikon addressed some nagging problems in microscopy for the period with the Eclipse E800 biological research microscope. Anti-dust construction is integrated into the stand design and users have the option of getting eyepiece tubes treated with an anti-mold formula for reliable performance in hot, humid regions of the world. Focus problems related to thermal changes in the microscope related to heat from extended illumination were reduced by using special insulating materials and heat shields.