This page contains Thorlabs' selection of test targets and stage micrometers for common metrology applications.

Test Targets
Test targets are typically used to measure the resolution of an imaging system. They consist of reference line patterns with well-defined thicknesses and spacings, and are designed to be placed in the same plane as the object being imaged. By identifying the largest set of non-distinguishable lines, one determines the resolving power of a given system. Grid arrays, which are made of a repeating square pattern, are a type of test target that can be used to identify and correct for distortions in an imaging system.

Thorlabs offers test targets with both 1951 USAF and NBS 1963A patterns from stock. For more information on each pattern, see the Resolution Targets tab.

Stage Micrometers
Stage micrometers are precise, fine-lined rulers that are designed to be easily read under magnification. By placing a stage micrometer next to an imaged object, the length or width of that object can be directly measured through a microscope.

All the parts shown here are manufactured at Thorlabs' in-house semiconductor device production facility in Jessup, Maryland. Our extensive production capabilities enable us to provide both stock and custom solutions for imaging system calibration and measurements. We use contact photolithography with a mask aligner to define the pattern on the glass substrate. The mask used is calibrated to NIST-traceable standards. Once the pattern is defined, we chemically etch the substrates and clean them in a class 100 cleanroom.

If your application requires a test target or calibration tool not seen here, please see the Custom Targets tab above or contact Tech Support for assistance. Thorlabs also offers a complete line of reticles for superimposing a reference pattern onto an object.

1951 USAF Targets

• Determine Resolution of Imaging System
• Conforms to MIL-S-150A Standard
• Positive and Negative Targets Available
• 10 Group 3" x 3" Targets, 6 Group 3" x 1" Wheel Pattern Targets, and 1 Group Ø1" Targets

Resolution targets have a series of horizontal and vertical lines that are used to determine the resolution of an imaging system. A set of six elements (horizontal and vertical line pair) are in one group and ten groups compose the resolution chart. The image to the right shows Elements 2 and 3 of Group -2 on a resolution target.

The spacing between the lines in each element is equal to the thickness of the line itself. When the target is imaged, the resolution of an imaging system can be determined by viewing the clarity of the horizontal and vertical lines. The largest set of non-distinguishable horizontal and vertical lines determines the resolving power of the imaging system. The chart below lists the number of line pairs per millimeter for a given element within a group based on the equation below. With our resolution targets, the maximum resolution is 228.0 line pairs per millimeter, which equates to roughly 4.4 µm per line pair. The 3" x 3" targets feature ten groups from -2 to +7; the 3" x 1" wheel pattern versions feature 9 targets, each with groups +2 to +7; and the Ø1" targets feature six groups, from +2 to +7.

NBS 1963A Targets

These targets have pairs of 5 vertical and 5 horizontal lines. Pairs of these are scaled from 1.0 cycle/mm to 18.0 cycles/mm. By determining the smallest lines that are distinguishable (highest cycles/mm), you can determine the resolution of an imaging system. The table below lists the cycles/mm on our NBS 1963A targets, along with a conversion of the cycle size (line width is half of the cycle size).

Custom Test Targets

Thorlabs has extensive design and production capabilities for test targets and reticles. All of our test targets, stage micrometers, distortion grids, and reticles are manufactured in-house at our Thorlabs Quantum Electronics (TQE) division in Jessup, Maryland. In addition to the 1951 USAF and NBS 1963A test targets that are offered from stock, we can provide custom patterns and sizes (circular, square, and rectangular), a sample of which are shown below.

Please note that there is a significant tooling cost and lead time for custom test targets that makes the purchase of only a few pieces fairly costly. For more information about our capabilities or for a quote, please contact Tech Support.