The products below represent our microscope XY stage and Z focusing stage options. If you do not see exactly what you are looking for, please contact us. We pride ourselves on having the knowledge and experience to solve your unique challenge. Over our history we have built thousands of assemblies.
About XY Microscope Stages
Traditionally, microscopes have been human operated, with the user looking into an eyepiece, but increasingly, microscopy is becoming automated. At the heart of many biomedical instruments lies an automated regular or inverted microscope.
In addition to basic functions such as controlling the digital camera, illumination and filter selection, microscopes require two critical positioning functions. One is to precisely position the sample in the XY plane. This can either be done with fast moves between adjacent fields (field sequential imaging), or precise constant velocity motion (scanning imaging). This XY motion is performed by an XY microscope stage, which is typically a thin, low-profile XY stage with a central opening for the optical axis.
Older manual microscope designs use a mechanical stage to move the sample. New automated XY microscope stages are typically actuated with stepper motors and lead screws, cutting-edge designs employ a linear motor and a linear encoder on each axis, and close a servo feedback loop. The second key positioning task in an automated microscope is a focus axis. This moves the objective relative to the sample so as to maintain critical focus at all times.
Traditional manual microscopes use micrometers to focus on the sample. Automated microscope focus axes typically use piezo or direct drive technology. Direct drive linear motors offer extended range, allowing the objective to be retracted during sample load and unload, together with very high resolution and repeatability. The focus axis position is typically commanded by an autofocus sensor, which derives a focus error signal via a laser diode passing through the objective or by a software autofocus algorithm.
Optimizing the Microscope XY Stage and Z Focusing Axis
Once the optical imaging elements are selected, the mechanical stage architecture can be finalized. A typical field of view is much smaller than the sample being imaged. Thus, in order to image an entire sample, either the sample or the camera / objective will need to move along two perpendicular axes (XY). In addition, in order to properly resolve the image, the distance between the magnification objective and the camera (or image sensor) needs to be precisely adjusted. This is referred to as the Z axis. The Z axis is typically vertical and motion along it, to move the sample into the imaging field of view, occurs perpendicular to the XY plane.
There are three common configurations of the mechanical stage motion hardware. Selecting the best one depends upon the particular application’s complexities.
1. The XY microscope stage moves the sample below a Z stage that is moving the objective or camera. This is the most common configuration. The benefit of this approach is that the image becomes stable after motion more quickly because it is only moving on one axis. This means it can be mounted to a sturdy structure instead of a stack of three moving axes whose resonances need to damp. During sample loading, the objective can be moved vertically away from the sample mounting area, which makes changing samples easier. Also, Abbe errors are reduced because the overall stack is shorter. To understand the impacts of Abbe errors on stage positioning, see our Abbe error white paper. This method works for regular or inverted microscope configurations.
Microscope XY stage moving slide, with separate Z axis moving objective
2. Three motion axes move the object being imaged in X, Y and Z directions while the camera and objective remain stationary. In this situation, the camera is very stable because it is mounted to a rigid surface. The drawback is that the travel required for the Z axis may be longer because the objective-to-imaging sensor distance is fixed. Typically, it requires less travel to move the objective with respect to the imaging sensor or camera.
3. The objective or camera is moved in X, Y and Z directions, while the sample remains fixed. This approach works best when imaging small parts such as a microscope slide. As part size increases, the complexity of this approach also increases. Larger travels tend to require two axes to support a beam that has the vertical focus axis with both the imaging sensor and objective mounted to it.
XYZ imaging with 500 x 400 x 300 mm travel for XYZ