The MFC-2000 has been specifically designed to provide a high resolution, and highly repeatable, means of controlling the focus / Z position of the microscope stage. Precise control of the microscope's focus is obtained through the use of a closed-loop DC servomotor employing high resolution encoders for positioning feedback. By using closed-loop control of the focus position, there is no chance that the focus point can be lost as can occur with open-loop stepper motors.

Rather than a one-size-fits-all design, the Z-axis drive is custom designed for each microscope, and when installed, they become an integral part of the microscope. A switch located on the control console operates a clutch that disengages the motor drive from the fine focus shaft when the drive is not needed. When disengaged, the position still displays and is still available for interrogation by computer and the microscope can be focused manually without any drag or twisting cables. Installation of the Z-axis drive requires no modification to the microscope other than removal of the fine focus knob and replacement of a back plate or base plate, depending on the particular microscope. All of the necessary hardware components, tools, and detailed instructions are provided with every unit.

The microprocessor-controlled MFC-2000 control unit provides for RS-232 communication with a host computer. High-speed serial communication using USB is also possible.

Features

• Closed-loop DC servo control of Z-axis for precise positioning and highly repeatable focusing
• Compact ergonomic tabletop control unit size is 6"D x 9"W x 3"H
• Backlit LCD display shows Z coordinates
• Utilizes ASI's proven Z-axis DC servomotor drives
• Z-axis clutch for easy switching between manual and motor-driven focus control
• "Zero" and "Home" button for simple stand-alone operations
• Microprocessor control with RS-232 serial communications
• USB serial computer interface

Specifications for Standard Configuration

Linear Encoder Options for Z-axis

Optional CRIFF Long-Term Focus Solution

The CRIFF Continuous Reflective-Interface Feedback Focus System provides a very high level of focus stability, substantially eliminating focus drift caused by temperature variations as well as mechanical drifts of the microscope mechanisms. The system monitors the distance between the objective lens and the specimen's cover slip, and commands an integrated ASI Z-axis drive to compensate for changes. CRIFF promises to be a solution to the focus drifts that plague time-lapse experiments at high magnification.

Auto Focus option is also available for systems with ASI Z-axis drives and requires a composite video signal (either NTSC or PAL).

Key Advantages

ASI's closed-loop DC servomotor systems provide a number of key advantages over common stepper motor focusing systems. Some of these advantages include:

Our drives use geared DC servo motors with position feedback from the focus shaft. This means, unlike stepper motors, full torque is available even for very small movements. A closed-loop servo system does the positioning. The stage position displayed on the control console is the actual stage position. It is available for interrogation by a computer.

On all of our drives, the original fine focus knob on the drive side of the microscope, usually the left, is brought out on an extension shaft. On some of our drives, depending on the microscope, the original coarse focus knob is accessible as well. When the clutch is disengaged (or the motor drive shut off), the microscope can be manually focused from either side with no added torque felt on the knob and no cable to twist up.

A remote focus knob on the control console has several useful purposes. It is a convenient means of fine focusing without having to reach in around a plethora of apparatus often surrounding the microscope during complex experiments. Where cell poking is taking place, it allows vibration free fine focusing. It allows either temporary or permanent altering of the focus during multi-plane, time-lapse imaging. If the focus commands issued by the computer are absolute, then the effect of adjusting the remote focus knob is canceled at the next command. This lets the researcher look around between commands. If the computer commands are relative, then the remote focus adjustment acts as a correction for changes taking place in the preparation being observed.

Our motor drives have lower electrical noise and lower mechanical vibration than do stepper motor drives. This reduces the likelihood of interference with other research equipment. Unlike stepper motors that are driven by fast rise and fall time (electrically noisy) current pulses, our drive signals are DC and essentially zero when the drive is not moving. Our power supplies are linear rather than switching supplies to make sure they do not introduce electrical noise. We shield our drive cables and power cords. The vibration is lower because DC servomotors, unlike stepper motors, do not have magnetic detents.