Microscopes & Accessories

Autofocus System

ASI Applied Scientific InstrumentationASI Crisp

Applied Scientific Instrumentation (ASI) manufactures hardware for laboratory and microscope automation including extremely precise closed-loop DC servo motor XY stages and Z drives for submicron motion control, piezo-Z stages for ultra-precise and fast Z-axis focusing with nanometer resolution, laser-based feedback systems for maintaining submicron focusing for days, video & LED based autofocus systems, open-loop stepper motor stages for use with existing OEM controllers, high-speed filter wheels and shuttering devices for illumination control, video microscopes and custom optical systems, microinjectors and micromanipulators for intercellular injections, cameras and photometric systems for imaging and quantification. ASI’s products are designed for long life under demanding applications and are backed with unparalleled support.

Website: https://www.asiimaging.com

ASIASI Crisp Autofocus System

ASI CRISP – Autofocus System

The CRISP system is designed to maintain focus over time i.e. compensate for thermal & other factors that may cause the sample to drift out of focus. It also can be used to maintain a given focal point while scanning the sample in XY. It provides continuous reflective interface sample placement in microscopy applications via 850 nm LED illumination. The system mounts to any microscope’s C-mount port and works with most normal microscope objectives, and offers focus accuracy <5% of the objective depth of focus (DOF).

Continuous Reflective Interface Sample Placement

  • Mounts onto any microscope’s standard C-mount port
  • Maintains ideal focus for days
  • Works with most normal microscope objectives
  • Low noise electronics allows locking to glass/water interfaces
  • Integrates with ASI Piezo-Z or motorized focus stages
  • Simple post-lock fine adjustment of focus
  • Automated control

Theory of Operation

The CRISP system projects the image of a mask illuminated with an IR LED into the sample plane. Only one half of the objective pupil is illuminated. This means that the point spread function of the objective is highly skewed, so that the reflected image of the mask will move laterally as focus is changed. CRISP detects this lateral motion of the LED image to obtain a focus error that is used to close the focus positioning loop.


CRISP is usually installed with ASI Dual C-Mount Splitter (DCMS) that contains the required dichroic beam combiner and blocking filters and provides the C-mount port for the camera.

Adjustments, Operations, and Control

  • Built-in C-mount extension for optical offsets
  • LED beam iris to match illumination beam to objective pupil for optimum performance
  • Lateral detector adjustment
  • Other LED colors possible
  • LED intensity control
  • Programmable gain and averaging functions to optimize system for stability or speed


  • Light Source: LED
  • Wavelength: 850 nm
  • Optical Interface: C-mount
  • Typical Focus Accuracy: <5% of objective Depth of Focus
  • Controller: MS2000 w/ CRISP card

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