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An ocular micrometer or eyepiece micrometer is a glass disk, engraved with a ruled scale, that fits in an eyepiece of a microscope, [1] [2] which is used to measure the size of microscopic objects through magnification under a microscope. When the eyepiece micrometer is calibrated using a stage micrometer, the length of the divisions on the ...
The chart was designed by Ian Bailey [5] and Jan E. Lovie-Kitchin at the National Vision Research Institute of Australia. [1] [3] They described their motivation for designing the LogMAR chart as follows: "We have designed a series of near vision charts in which the typeface, size progression, size range, number of words per row and spacings were chosen in an endeavour to achieve a ...
The aim of an accurate intraocular lens power calculation is to provide an intraocular lens (IOL) that fits the specific needs and desires of the individual patient. The development of better instrumentation for measuring the eye's axial length (AL) and the use of more precise mathematical formulas to perform the appropriate calculations have significantly improved the accuracy with which the ...
Christiaan Huygens, another Dutchman, developed a simple 2-lens ocular system in the late 17th century that was achromatically corrected, and therefore a huge step forward in microscope development. The Huygens ocular is still being produced to this day, but suffers from a small field size, and other minor disadvantages. [citation needed]
The formal definition of calibration by the International Bureau of Weights and Measures (BIPM) is the following: "Operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties (of the calibrated instrument or ...
A set of gauge blocks are used as a working standard to check the calibration of measurement tools such as micrometers.. An example of a primary standard was the international prototype of the kilogram (IPK) which was the master kilogram and the primary mass standard for the International System of Units (SI).
The Munnerlyn Formula is the theoretical formula [1] discovered by Charles Munnerlyn which gives the depth an excimer laser will need to ablate during LASIK surgery or similar medical interventions. The formula states that the depth of the ablation (in micrometres) per diopter of refractive change is equal to the square of the diameter of the ...
According to Braun, the standard gold-leaf electrometer is good up to about 800 V with a resolution of 0.1 V using an ocular micrometer. For larger voltages up to 4–6 kV Braun's instrument can achieve a resolution of 10 V. [2] [3]