Jan Braasch

Wavelength determination of semiconductor lasers: precise but inexpensive

Precise optical wavelength measurements can be performed by use of a novel wavelength sensor. This low-cost sensor consists of a wavelength-sensitive photodiode and a high-precision log ratio amplifier. The center wavelength of monochromatic or narrowband light sources such as semiconductor lasers in the visible or near-infrared wavelength range can be determined. By simultaneously testing the properties of monomode laser diodes with a standard wavemeter, the feasibility and precision of the wavelength sensor are demonstrated. Wavelength variations less than 0.1 nm are detected clearly.

A Study on the Development of a Three Dimensional Linear Encoder System for In-Process Motion Error Calibration and Compensation of Machine Tool Axes

Abstract In-process measurement of volumetric accuracy is an effective method to enhance the machine tool motion accuracy for quality machining operations. This paper describes a new three dimensional linear encoder system for measuring the on-axis volumetric accuracy of machine motion. The proposed system consists of three cross-grid grated scales with three sensor-heads, each of which includes six opto-electronic sensing elements. The system uses a noncontact scanning principle to detect six degree-of-freedom motion errors. These represent three linear and three angular displacements along a moving axis. The evaluation tests on the prototype system have successfully demonstrated the feasibility of the proposed technology.

A Novel Approach For Simultaneous Measurement Of The Linear Guideway Errors Of A Machine Tool With A Volumetric Optical Encoder

Precision machine tools require in-process measurement of volumetric accuracy for machining and calibration. This paper describes the development and evaluation of the mounting of a previously presented volumetric linear encoder for measuring the onaxis volumetric motion accuracy. The encoder is based on three cross-grid gratings as measurement bodies and a sensor-head consisting of six optical sensing elements. In order to implement this device for machine tool testing, mounting flexures were used as mounting link. This allows repeatable measurements under varying environmental conditions.