An optical bench is a rail or aligned platform carrying an object, optical lens elements and a screen or detector at readable positions. It turns image formation into measurements of position and transverse magnification. Read distances between the optical planes rather than arbitrary holder boundaries; keep heights and optical axis alignment controlled. [ref]
https://www.pasco.com/resources/lab-experiments/484. PASCO, Object and Image Distances Thin Lens: bench apparatus and measurements
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