Abstract: A method for gesture recognition in an optical system using a touchless slider is shown. The touchless slider has first and second reference points positioned along an axis in an optical system. The method includes obtaining a plurality of first and second reflectance values by measuring an amplitude of light reflected from an object relative to the first and second reference points, respectively, wherein each first and second reflectance value corresponds to a different point in time. The plurality of first and second reflectance values are compared to identify a plurality of ratio values between the first and second reflectance values, wherein each of the plurality of ratio values corresponds to one of the points in time. At least one of a position and a direction of movement of the object relative to the first and second reference points is determined based on the identified plurality of ratio values.