The development of a low-cost focusing probe for profile measurement

Abstract

A high-precision optical probe based on the principle of focusing-range detection is developed in this research. The probe adopted for use was directly taken from the pickup head of a CD player. Because its principle is similar to that of the autofocusing probe, the characteristics of each component of the head were investigated and its conversion into a focusing probe was attempted. The S-curve within the focusing range can be analysed, revealing the linear relationship between the normalized focus-error signal (FES) and the measured distance. The system accuracy of the probe was found. Within the measurement range of 10 µm the linearity error was about 1%, the standard deviation was about 34 nm and the frequency response was about 8 kHz. Some practical applications were carried out, namely profile measurements of a step height, a CD surface and a silicon-wafer grating. All results were highly consistent with the nominal values.

A lateral super-resolution differential confocal technology with phase-only pupil filter

“…Although the DCM lateral resolution is 1.4 times better than those of other laser probe measurement systems (LPMS), such as astigmatic method, critical angle and interferometry method [6][7][8][9], under the same conditions, its lateral resolution is still two orders of magnitude below its axial resolution. This made it very difficult for DCM lateral resolution to satisfy the stringent requirement for high LPMS spatial resolution while 3D microstructures, such as microstep, microgroove and integrated circuit line width, etc., are measured, i.e.…”

Development of a novel profile measurement system for actively planed surfaces

“…It must be mentioned that, surface profiling with the DVD pickup as a sensor is not exactly a novel approach and similar research has been carried out in the past [12][13][14][15][16][17]. However, the profiles measured were 'ideal' surfaces such as CD, mirror and Silicon substrate.…”

Probe Technologies for Micro/Nano Measurements

“…2. Previous studies showed that on a single material, such as DVD disk, this probe can accurately measure 3D surface to nanometer accuracy (Fan, 2000;Mastylo, 2004). Products fabricated by NEMS process are, however, mostly built up different materials on the silicon substrate.…”