> For the complete documentation index, see [llms.txt](https://help.connected.illumina.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.connected.illumina.com/dragen-stratamap/illumina-spatial-image-tool/optical-target-test.md). # Optical Target Test Before processing images for the Illumina Spatial Transcriptome Assay, the Optical Target Test should be performed using the Illumina Bright Field (BF) Optical Target. This test is intended to evaluate whether the image quality produced by a microscope is suitable for use with the Illumina Spatial Transcriptome Assay. The images captured during this test are used as input for the Illumina Spatial Image Tool (ISIT) during the *Assess Microscope* workflow. {% hint style="info" %} The Optical Target Test is designed for use with microscopes and is not intended for slide scanner imaging systems. {% endhint %} {% hint style="info" %} Illumina recommends using a slide scanner for imaging, as microscopes require manual adjustments, more experience with imaging principles, and additional training and practice for accurate results. {% endhint %} The Optical Target Test provides the following key metrics: * Estimated pixel size (microns) of the camera * Full Width Half Maximum (FWHM) for assessing focus quality * Shading uniformity observed in the FOV * An optical distortion heatmap The Illumina BF Optical Target is a 75 mm x 25 mm x 1 mm slide featuring patterned elements in the center. This test must be conducted using the 20X objective lens and the specific camera intended to be used with the Illumina Spatial Transcriptome Assay. The microscope assessment includes evaluation of focus quality, detection of stage tilt, analysis of optical distortion, and assessment of shading uniformity. These metrics are valuable for diagnosing and troubleshooting image quality issues. Here are the articles in this section: * [Imaging the Illumina Optical Target](/dragen-stratamap/illumina-spatial-image-tool/optical-target-test/imaging-the-illumina-optical-target.md) * [Microscope Assessment](/dragen-stratamap/illumina-spatial-image-tool/optical-target-test/microscope-assessment.md) --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://help.connected.illumina.com/dragen-stratamap/illumina-spatial-image-tool/optical-target-test.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.