High-precision semi-spherical meter of two degrees of freedom

J. G. Vera-Dimas; M. Tecpoyotl-Torres; S. E. Martínez-Fabián; J. Escobedo-Alatorre; L. Cisneros-Villalobos; O. G. Ibarra Manzano; J. Sanchez-Mondragon

doi:10.1117/12.930159

11 October 2012 High-precision semi-spherical meter of two degrees of freedom

J. G. Vera-Dimas, M. Tecpoyotl-Torres, S. E. Martínez-Fabián, J. Escobedo-Alatorre, L. Cisneros-Villalobos, O. G. Ibarra Manzano, J. Sanchez-Mondragon

Author Affiliations +

Proceedings Volume 8486, Current Developments in Lens Design and Optical Engineering XIII; 848618 (2012) https://doi.org/10.1117/12.930159
Event: SPIE Optical Engineering + Applications, 2012, San Diego, California, United States

Abstract

The semi-spherical meter uses a photo-detector mounted on a mobile rectangular arc, which by means of two stepper motors describes the semi-spherical trajectories required. For controlling motors and data acquisition, a Peripheral Interface Controller (PIC) is employed, which helps keeping the low cost of the overall system. One of the stepper motors is located on the lateral axis of the device; that displaces the sensor along a semi-circular trajectory of 170°, almost complete meridians. Another motor located at the base of the device enables 360° rotation of the illumination source under test. The precision is increased by the using of two angle sensors located on the opposite lateral axis and on the mobile base of the illumination source. Additionally, before the data obtained from the photo-detector arrive to the PIC, a stage of signal conditioning is used. This step allows us to increase not only the precision, but also the versatility of the meter to analyze illumination sources of different sizes and fluxes. The communication protocol between the data acquisition stage and the computer is USART. A graphical user interface (GUI) is employed on the base of the hyperterminal. The number of measurement points is determined by programming the two motors. The mechanical structure provides enough rigidity for supporting the accuracy required by the data acquisition circuitry based on a PIC. Measurement of illumination sources of different sizes is possible by using adjustable lengths of the mobile base and the ring.

Citation Download Citation

J. G. Vera-Dimas, M. Tecpoyotl-Torres, S. E. Martínez-Fabián, J. Escobedo-Alatorre, L. Cisneros-Villalobos, O. G. Ibarra Manzano, and J. Sanchez-Mondragon "High-precision semi-spherical meter of two degrees of freedom", Proc. SPIE 8486, Current Developments in Lens Design and Optical Engineering XIII, 848618 (11 October 2012); https://doi.org/10.1117/12.930159

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