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If the crossed polarizers are aligned with the sides of the glass covers, the positive image will be formed. Additionally, it can display both positive and negative patterns by changing the orientation of the crossed polarizers. The entire target has a retardation of 280 ± 20 nm. The device is engineered so that the fast axis of the overall target is aligned parallel to the side of the glass covers, whereas the fast axis for the patterned area is aligned 45° to this edge. It is created by using a photo alignment process to set the fast axis of the liquid crystal polymer layer, which is protected by two N-BK7 glass covers. The R2L2S1B Birefringent Resolution Target has a pattern that is invisible unless viewed through a pair of crossed polarizers, making it ideal for calibration of polarization-sensitive systems.
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Once the pattern is defined, we chemically etch the substrates and clean them in a class 100 cleanroom. We use contact photolithography with a mask aligner to define the pattern on the glass substrate. Our extensive production capabilities enable us to provide solutions for imaging system calibration and measurements. For users of the MLS203 Microscopy stage we offer the MLS203P2 Slide Holder for Inverted Microscopes, which can mount slides 25 mm to 26.5 mm wide and petri dishes 30 mm to 60 mm in diameter. Please note that the mount's support arms overlap the optic by 4.4 mm on each side. The XYF1 uses nylon-tipped setscrews to secure the optic. The mount offers five 8-32 (M4) taps for six post-mountable orientations. Thorlabs also offers our XYF1(/M) Test Target Positioning Mount (see photo to the right) capable of translating a 1" to 3" wide rectangular target over a 50 mm x 30 mm area. The MAX3SLH is only compatible with test targets greater than or equal to 2" wide and provides a clear aperture of 1", which may cover the chrome pattern on some of the test targets. Our MAX3SLH Fixed Slide Holder provides two spring clips to mount the optic and can be mounted to any of our 3-axis translation stages. These resolution test targets can be mounted in one of four of our microscopy slide holders. Each pattern is manufactured using photolithography, allowing for edge features to be resolved down to approximately 1 µm. See the Graphs tab for spectral data of the materials used in these test targets. The positive reflective targets are composed of an antireflection-coated (AR-coated) chrome pattern etched on soda lime glass with an uncoated chrome background for high contrast in reflective applications. The negative targets use chrome to cover the substrates, leaving the patterns clear, and work well in back-lit and highly illuminated applications. The positive targets consist of low-reflectivity, vacuum-sputtered chrome patterns plated on clear substrates and are useful for front-lit and general applications. We also offer several versions of high-contrast positive reflective targets. For more information on each pattern, see the Resolution Targets tab.Īll of our resolution test targets are available as positive targets, and many have negative versions as well. Targets are also available with sector star (also known as Siemens star) patterns, Ronchi rulings, a variable line grating, or a combination of patterns for resolution and distortion testing. Thorlabs offers resolution test targets with 1951 USAF, NBS 1952, and NBS 1963A patterns. By identifying the largest set of non-distinguishable lines, one determines the resolving power of a given 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. Resolution test targets are typically used to measure the resolution of an imaging system.
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