Hardware Design - Our hardware contains major differences which may not be evident. We provide a patented fixed lenslet mounting directly in front of the camera detector. While simple in appearance, a great deal of engineering has gone into this design.
- Vibration resistant - This rigid design provides a completely vibration insensitive system no matter what the environment.
- Thermal stability - Lumetrics' lenslet mounting design also provides better thermal stability than low-cost wavefront sensors. This is important because thermal stresses directly affect the position and alignment of the lenslet array, which affects accuracy and repeatability of optical measurements.
- Calibration & Accuracy - With over 200 systems in the field, no system has lost its calibration or fundamental accuracy. This accuracy is set at the factory and does not degrade because of this patented mounting.
Software Design – The CLAS-2D software package is the most flexible and thorough in the industry.
- Comprehensive SW package – Instead of separate modules for different applications, the Lumetrics® CLAS-2D software provides an integrated package with access to all the features.
- Centralized control – Control panel allows operation of most commonly used operations and immediate data analysis with a click or two of the mouse. Macro language products require the customer to configure the system and essentially write software to accomplish any operations.
- Permanent calibration - Lumetrics analysis software permanently stores the factory reference file in the computer for a lifetime of accurate measurements. Some low-cost wavefront sensors do not store reference files. That requires users to continually re-calibrate their wavefront sensors for accurate measurements.
Read more about the CLAS-2D™ system advantages.
The basic geometry of a Shack-Hartmann based sensor is shown here. The sensor consists of two basic parts: a lenslet array and a position-sensing detector. The incoming light is dissected into a number of small samples by the lenslet array, which then focuses the light onto the detector array. A wide variety of methods for fabricating lenslet arrays have been used. Early examples were built through the juxtaposition of a number of small lenslets glued or fixed in an assembly. The use of binary optics and other micro-optics technology has greatly improved the accuracy, resolution, and fill factor of the lenslet array. There is a whole art devoted to the design, fabrication, and characterization of such elements that is beyond the scope of this page. More information can be found on the Info Center, WaveFront Resources. The lenslet array thus creates a number of separated focal spots of light on the detector. The key principle is that the position of these focal spots is directly related to the average wavefront slope across the lenslet. Thus a measurement of the focal spot position uniquely determines the wavefront slope for that sample if the other system parameters are known.
A position-sensing detector determines the focal spot position. Commonly, a CCD detector is used for this purpose. This allows a flexible measurement since it allows even dynamic allocation of detector pixels to the focal spots. An algorithm that processes the detected image and locates the focal spots determines the focal spot position. The wavefront slopes are computed by comparison to a reference and the wavefront through reconstruction from the array of wavefront slopes.
CLAS-2D™ uses a micro-optic lenslet array to dissect a light beam into multiple focal spots. The positions of these focal spots are used to measure the optical wavefront.
- Wavefront Analysis
- Application of Shack-Hartmann Wavefront Sensing Technology to Transmissive Optic Metrology
- Application of Shack-Hartmann Wavefront Sensors to Optical System Calibration and Alignment
- Shack-Hartmann Wavefront Sensor Precision and Accuracy
- CLAS-2D™ System Advantages