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The term fine adjustment screw typically refers to screws with threads from 40 to 100 TPI and ultra fine adjustment screw has been used to refer to 100–508 TPI. Even though these are non-standard threads, both ISO metric screw thread designations and UNC designations have been used to call out thread dimensions and fit. A typical use for a fine adjustment screw is in an optical mirror mount as an adjuster. Typically 80 TPI screws are used in mirror mounts. Ultra fine adjuster screws are used in applications requiring extremely fine motion like laser alignment, fiber coupling.
Fine and ultra fine adjustment screws are often used in photonics applications as part of purchased equipment or built into lab made apparatus. Often, screws are purchased with matching bushings to be integrated into an experiment or commercial product once attained. Fine adjustment screws and mirror mounts are available as standard items from most companies that sell optics hardware.