Ten Metrics for a Highly Effective True Microscope Autofocus System



Are you looking for a true microscope autofocus system? One that:



  • Acquires and holds focus automatically, even on very difficult surfaces
  • Maintains focus to sub-micrometer tolerances for extended exposures
  • Provides adjustable offsets for cover slips and other intervening surfaces
  • Offers a rich feature set to help automate your system?
  • Delivers “no excuses” performance?


Many “Autofocus Systems” are not true autofocus systems.



Some are only thermal drift suppression (position holding) devices that need to be reset at each new location. Some don’t even sense focus, but only hold a single positon. We regularly replace these instruments for disappointed customers who bought these less capable “autofocus” systems. All Focal Point autofocus systems are true automatic focusing systems. ​



Here is a brief description of FocusStat 5’s Ten Metrics for Highly Effective True Microscope Autofocus. More detail on this subject is available below. Our point is that FocusStat 5 is capable, well characterized—and we guarantee its performance.

  1. Hands-off Capture range: >5 mm @ 10X
  2. Stability over time: <10% of DOF, 72 hours @ 20 +/-5C
  3. Static measurement precision: 1% of DOF; 10% of DOF @ 75 mm/sec
  4. Tilt latitude: +/-7 degrees at 10X (14 degrees @ 20X, etc.)
  5. Available focus offset: 75% of item #1
  6. Automatic Performance Measurement, and reporting: Software Button
  7. Averaging: Variable Spot, Line or Area as selected by user
  8. Connectivity: USB-A, with proprietary Focus Tool
  9. Motor supported: Any +/- 10V or 0-10V < 1A analog input
  10. Time required, OFF to full operation in industrial mode: <30 seconds


By way of illustration, four photos below were made by FocusStats—completely automatically, with no operator intervention, while moving across difficult samples at speeds up to 100 mm per second.



Area Sampling on
Interrupted Surface



Line Sampling/Rough Surface



Point Sampling on
Semiconductor



Inkjet Printing
on Paper



FocusStats were invented for demanding industrial autofocus applications and they are very good at it. But that is not all they do.



Focal Point’s instruments excel at:

  • Holding correct focus on difficult surfaces
  • Following fast-moving samples
  • Maintaining clear focus for unlimited periods of time
  • Versatility and adaptability
  • Robustness and ease of use


Here are three images of the industrial inspection version. FocusStat 5 is installed as an epi illuminator, which fits easily into upright microscopes. There are many other ways to use FocustStat 5, as well.



Like all FocusStats it is a true autofocus system. This one is similar to an epi illuminator, and fits easily into an upright microscope.


Here are some additional uses for FocusStat 5, based on past projects:



  • Laser scribing of solar cells through a glass cover, for commercial production (frequency doubled scribing laser, focus @ 670 nm)


  • Super resolution version for commercial inverted biological microscopes


​

  • Modular microscope for industrial inspection


  • YouTube Video: A live video of yeast cells on a well plate, showing automatic positioning in X and Y, plus fully automatic focusing. 96 wells can be visited in less than 30 seconds.


Why Not Compare?



How does FocusStat 5 compare with other “Autofocus Systems”? Below is a checklist that we use to design, build and test fully automatic focusing systems. It is the source of “10 Metrics for a Highly Effective True Microscope Autofocus Systems” that is used above to specify FocusStat 5 performance.


Ten Metrics for a Highly Effective True Microscope Autofocus System

  1. Range of fully automatic focus capture
  2. Long term Focus stability
  3. Signal to noise ratio (SNR) of the focus signal
  4. Focus stability on moving, tilted, patterned or interrupted surfaces
  5. Amount of user-adjustable focus offsets
  6. Extent of focus system self-diagnosis
  7. Configurability of surface averaging—e.g. spot, line or area
  8. USB connectivity/host software capability
  9. Adaptability to multiple focus motor types
  10. Simplicity/robustness of operation in production settings


Next, a blank version of 10 Metrics. We suggest you copy this form and have other suppliers complete it to get a direct comparison with FocusStat 5. Past experience tells us that the results of the comparison will be interesting.



We welcome comparisons between our FocusStats and other autofocus systems. Sales literature—which is usually written by the marketing department—tends toward glowing adjectives. Ours is written by engineers and is based on hard data. For that reason, we recommend using measured data.



Tutorials



We are in process of adding background tutorials to explain each of the metrics. At least 9 more tutorials will follow, based on “Ten Metrics for a Highly Effective True Microscope Autofocus System”. We will add these tutorials as time permits, so check back often. We welcome your comments and questions.


Meanwhile, contact us if you need help or have questions…send us your samples…or pay us a visit—we will be happy to discuss your project, all without cost or commitment.



Focal Point, Inc.

The No-Excuses Autofocus Company

208-362-6142.