Method and apparatus for thin film quality control

A method of determining parameters of a photovoltaic thin film deposited on a substrate in a patterned photovoltaic panel, the panel being a plurality of individual photovoltaic cells, said method comprising:

• providing at least one photovoltaic cell panel and one or more optical sampling systems;
• enabling relative movement between the optical sampling system and the panel, and controlling the movement;
• identifying locations of individual photovoltaic cells on the panel;
• and
• synchronizing each sampled point location such that the sampled point reading takes place, when the sampled point is located at a pre-determined place along the panel movement path;
• wherein the reading is performed in at least one of a group of illuminations consisting of polychromatic or monochromatic illumination.

A method of a thin film large area photovoltaic panel quality control, said method comprising:

• illuminating a section of a working plane by at least one of a group of illuminations consisting of polychromatic illumination and monochromatic illumination, said working plane coinciding with said thin film plane;
• sampling a number of discrete points located in said illuminated section of the thin film and determining the spectral signal of the light collected by each of said sampled points;
• comparing the actual spectral signal of each of said points with a theoretical spectrum signal stored in a memory;
• determining deviations of the determined spectral signal from said theoretical spectrum signal for at least one thin film parameter characterizing said point;
• and
• wherein the amount and severity of the deviations indicate the quality of the photovoltaic thin film.

A method for thin film solar panel quality control, said method comprising:

• mapping locations of individual photovoltaic cells forming a thin film photovoltaic panel;
• capturing at least one of reflected, transmitted, and scattered light, containing a plurality of wavelengths, from the surface of at least one of individual photovoltaic cells and directing it to a light intensity and wavelength sensitive detector;
• and
• processing said captured light intensity and wavelength to derive at least one of a group of photovoltaic thin film parameters consisting of the thin film thickness, refractive index (n), extinction coefficient (k), absorption coefficient, energy gap, conductivity, crystallinity, crystal phase, material composition, surface roughness and spectrum and intensity of photoluminescence.

A system for photovoltaic thin film quality control, said system comprising:

• at least one of a group of illumination units consisting of polychromatic illumination unit and monochromatic illumination unit operatively configured to illuminate a line in a working plane of the system, said plane coinciding with the photovoltaic thin film plane;
• a sampling unit operatively configured to sample reflection, transmission, and scattering of one or more sampled points located in the illuminated section and selected such that a straight line can be traced through all of the sampled points;
• a calibration facility configured to prepare a concordance table containing coordinates of sampled points on the measured photovoltaic thin film to their coordinates in the sampling unit, said facility including at least a scanning mirror movable along the illuminated section and sized such that at any location it reflects light from one sampled point only;
• a control unit operatively configured to synchronize operation of the illumination sources and the sampling unit, communicate with forward and backward located thin film production stations, and process the sampled data;
• and
• wherein the processing of the sampled data by the control unit includes comparison of said data to a theoretical spectral data calculated for a predetermined set of parameters of at least one measured film, calculation of at least one thin film parameter by combining the measurement results obtained under polychromatic and monochromatic illuminations.

A method of a photovoltaic thin film quality control, said method comprising:

• illuminating a section of a photovoltaic thin film by at least one of a polychromatic illumination source and a monochromatic illumination source and forming on the thin film a substantially continuous illuminated line;
• designating a plurality of discrete sampled points located on said illuminated line said points to be imaged onto an optical switch;
• generating a concordance between the coordinates of the above sampled points on the thin film and their coordinates on the optical switch;
• using a detector adapted to receive each of said illuminations to sequentially sample each of said points by optically switching between the points;
• and
• determining the spectral signal of the illumination reflected or transmitted or scattered by the sampled points;
• deriving from the spectral signal at least one of a group of the photovoltaic thin film parameters consisting of the thin film thickness, refractive index (n), extinction coefficient (k), absorption coefficient, energy gap, conductivity, crystallinity, surface roughness, spectrum and intensity of photoluminescence, crystal phase and material composition.