Abstract: A method of reading an array of moieties such as polynucleotides (for example, DNA) on at least a portion of a surface of a transparent slide which is opposite a first portion on the opposing surface, which array has been previously exposed to a sample. The method may include mounting the slide on a slide holder and retaining the slide thereon in a mounted position in which the holder does not contact the previously exposed array. The holder is then inserted into an array reader and the array read. A holder and slides which can be used in the method are also provided.