General Description
The dioptometer is a precision instrument useful in determining accurately the diopter setting of another instrument. It is placed between the eye and the instrument to be checked. The focusing sleeve of the dioptometer is then adjusted until the field is in sharp focus. The diopter setting of the instrument being checked is then read from the sleeve of the dioptometer. Set at zero setting, the dioptometer can be used to check the accuracy of the zero diopter setting in the collimating telescope itself, which is commonly available for checking zero diopter setting.