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Vertical Z Stages

Modern biomedical, life science and diagnostic instruments rely on automated digital microscope technologies. DNA sequencers, cell imaging instruments, and digital pathology scanners are just a few of the many applications for digital microscopy solutions.

Dover Motion offers a variety of standard vertical Z stage options in addition to our core strength in collaborating with our clients to understand their needs and configure optimized vertical Z stage solutions to fit their unique application. When defining an appropriate Z stage, there are a lot of options to consider which involve tradeoffs in architecture, performance, throughput, and cost.

Z stages are a unique type linear translation stage which provide high precision linear motion in the vertical direction. These include Z stages for sample positioning, often referred to as Z-Lift stages, and traditional Z stage architectures for objective focusing.

Microscope Z Stage Demo with Objective

Z Stage Products

Microscope Z Stage

DOF-5™

The DOF series vertical Z stage has been optimized for optical microscopy applications. Eliminates alignment headaches.

Travel5 mm
Resolution1.25 nm
Repeatability< 50 nm
Bandwidth> 225 Hz
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ZE Microscope Stage

ZE™ Vertical Stage

Our elevator wedge vertical ZE stage provides a small footprint with a 200-millimeter-square moving table.

Travel12 - 38 mm
Accuracy15 μm TIR
Repeatability< ± 1.5 μm
Payload10 kg
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Custom Z Stage Designs

We have over 50 years of experience working with OEMs to optimize motion for objective focusing and vertical Z lifting applications.

Our engineers have developed unique motion control architectures for precision motion specifically tailored for vertical Z motion within many applications.

When it is time to develop your next focusing instrument, consult with our motion industry experts to determine which of the latest technologies make the most sense for your application.

XYZ Stages and Custom XYZ Stage Designs

 

Additional Z Stage Resources

Objective Focusing Calculations Explained
4 Steps to Optimize the Optics

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4 Steps to Optimize the Optics

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1. What are Z stages?

Z stages provide vertical motion.  Typical precision Z stages are used for moving an objective for focusing an image.  The biggest challenge with any Z stage design is overcoming the forces of gravity which work with or against the motion. Each axis of a linear stage must constrain the six degrees of freedom (X, Y, Z, roll, pitch, and yaw) of the payload to only one, producing translation along a straight line. A vertical z stage aims to minimize motion in the other 5 degrees of freedom.

2. How do Z stages work?

Z stages have bearings to constrain the motion along just the vertical axis.  In order to overcome the forces of gravity a magnetic counterbalance or pneumatic counterbalance can be used to minimize the load on the Z stage motor.  Another approach is to drive the vertical motion by moving a wedge horizontally, these are known as wedge Z stages.

3. What are the advantages of direct drive linear motor stages over piezos for Z stage motion?

For Z stage motion, direct drive linear motor stages provide multiple benefits not available to piezoelectric nanopositioners such as:

  • Fast move and settle times
  • Larger travel compared to flexure based stages
  • Higher servo bandwidth, with a better response
  • Very high stiffness; less compliance typical to flexure stages
  • Extremely long service life, with no need to vary servo tuning
4. What are the limitations of using Piezo Actuators within Z axis (vertical) motion control?

A typical multi-axis imaging application involves a piezo stage moving an objective vertically for focusing. The use of piezo and flexure-based stages for Z focusing in this situation has many drawbacks. Typically, a piezo stage can only move a maximum o 300 nm. It moves in small distances very precisely; however, the initial steps of focusing often requires larger movements. The larger moves are necessary for avoiding objective collisions with the sample or for finding the optimal focusing plane due to sample variations. Because of their movement limitations, piezo stages may have difficulty accommodating thicker samples such as tissue samples.

Also, the XY stage motions or other vibration sources such as pumps and fans in the microscope or diagnostic instrument can impart off-axis forces on the flexure which results in instability of the piezo stage. The stiffness of a system is referred to as bandwidth, and piezo stages with flexures are typically lower bandwidth compared to a stage using a linear motor or screw combined with a crossed roller bearing.

Another drawback to piezo stages is that the advanced crystalline materials (PZT) used in piezoelectric motors are expensive to produce and frequently include lead and other potentially hazardous materials. Piezo controls are also costly and are frequently complex to operate.

5. How does a digital microscope work?

This automated digital microscope consists of a programmable high precision XYZ stage. This system does automated focusing, automated XY motion, and has a CCD camera replacing the human eye. The field of view of a microscope is typically very small. It can be a fraction of a millimeter to perhaps two millimeters, and, the sample is much larger. To overcome that, an automated microscope will take many pictures of the sample across the X and Y space of the slide. For more information, visit our Automated Imaging Page.

6. What is High Precision Motion Control?

Dover Motion can address the performance requirements of your most demanding applications, and has over five decades of experience designing precision linear stages, rotary stages, and complete precision motion control systems.

Our skillset in high-precision multi-axis motion control includes:

  • Precision surface grinding, both pre- and post-hard coating
  • The use of advanced materials such as alumina ceramics, carbon-fiber, Zerodur, and diamond-like carbon
  • Structural exterior and interior light-weighting for maximum stiffness/mass ratio
  • Skills in the use of cutting-edge position and angle metrology instrumentation
  • 2-D and 3-D software compensation of residual stage errors
  • In-house design of both ironless and iron-core linear servo motors
  • Expertise in control theory and the design of high-performance servo loops
  • In depth knowledge of precision motion control system design

High precision positioning stages serve a wide array of applications and can be considered “high precision” for various difference reasons. For some XYZ stages, it is critical to minimize geometric errors and provide true XYZ stage accuracy within the working area or volume. In other cases, one or more precision motion axes are required to move with exceptionally constant velocity. These systems often require that periodic triggers be generated at extremely precise positions, and that encoder cyclical error be eliminated.

In other applications, minimizing position jitter when stopped is paramount with permissible jitter being only a few nanometers. This requirement is often coupled with a need to move very quickly from position to position. For yet finer position stability, Coulomb friction can be engaged, reducing jitter to 10 to 20 picometers.

Dover Motion has extensive experience in providing precision motion control solutions configured to fit many different applications and can address even the most challenging requirements.

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