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Troy, MI, United States

A reverse interferometric method for the determination of the thickness of a layer of material employs a multi-wavelength light source which generates a light beam which comprises a time-variant series of different monochromatic wavelengths. The beam is reflected from the body of material being measured and is detected by a broad spectrum wavelength detector which produces a signal comprising a series of data points indicating the reflectivity of the sample as a function of the time-variant series of monochromatic wavelengths. A signal processor processes these data points to fit them to a model waveform, and the frequency of the model waveform is used to calculate the thickness of the body of material. Further disclosed are apparatus for carrying out the method and use of the method in a continuous process for the fabrication of thin film materials.

United Solar Ovonic | Date: 2010-05-14

A system and method for measuring the velocity of gas flow between multiple plasma deposition chambers is provided. A passage atmospherically linking two plasma processing chambers conducts a gas flow therebetween due to differential pressures within the respective chambers. The gas flow velocity is measured by a linear or non-linear ultrasonic energy acoustic path between two transducers located exteriorly to the chambers using the difference in transit time in a forward and reverse direction due to the velocity of gas in the passage. The pressure of process gas in one or more chambers is adjustable based on the measured velocity of gas flow in the passage.

United Solar Ovonic | Date: 2011-07-13

A process for detecting and terminating a fault in a photovoltaic device is provided that operates in the millisecond or faster timescale. A process includes measuring a current or voltage in each of a plurality of strings relative to a common rail. When the voltage or current from a string is outside a predetermined threshold, a flag is generated indicating the presence of a fault in the string. A control unit will detect the flag and disconnect the faulty string from the system through a switch. The use of continuously rolling averages of baseline currents and voltages as well as a series of measurements averaged to measure the difference of current or voltage at each step provides a process and a fault detection system that does not suffer from false fault detections thereby providing a reliable and efficient system for detecting and terminating faults in photovoltaic devices.

United Solar Ovonic | Date: 2011-09-01

Processes of identifying small pressure irregularities in a system used for continuous plasma deposition are provided. Sensitive light scattering is used to detect the presence of nucleated particles in a detection area that is outside the plasma region of high electric field whereby the presence of the particles indicates a pressure abnormality in the plasma deposition chamber. The pressure of the plasma deposition chamber is then adjusted to reduce or eliminate the presence of particles within the detection area and to optimize deposition of material on a substrate.

United Solar Ovonic | Date: 2012-07-19

A pinch valve assembly includes a valve body having a slot which is configured to allow a web of substrate material to pass therethrough. The valve body has a sealing surface which includes a first curved portion with a first radius of curvature. A dynamic seal element is configured to engage the valve body and includes a second curved portion having a second radius of curvature which is larger than the first radius of curvature. An actuator is operable to selectively bias the dynamic seal element into and out of engagement with the valve body so that when it is biased into engagement with the valve body the web of substrate material is engaged between the sealing surfaces of the dynamic seal element and the valve body. Also disclosed are deposition systems which include these pinch valves.

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