Article: Measuring Lasers Used In Photovoltaic Solar Panel Manufacturing

One of the recent developments in the photonics industry has been the rapid increase in automated solar panel production facilities.1 Many of these end-to-end production lines use laser-based methods to manufacture the thin film silicon photovoltaic modules. The lasers used for this activity are generally diode-pumped solid-state lasers (DPSS) at 1064nm, 532nm and 355nm with beams focused to around 30µm.2 They are run at powers or energies that, although not extremely high, have high power or energy densities at these small beam diameters. The techniques used often call for multiple beams, running in parallel, to make precise cuts to electrically isolate the sections of the photovoltaic sheets. To ensure that these cuts are uniform, it is important to measure the beam profiles.

Measuring the profile of a high power density beam with a small diameter can be tricky. Cameras are not very good at measuring beams with diameters of less than 50µm, and the attenuation required for the high power or energy densities can be substantial. The attenuation can also be a source of beam distortion, which adds great uncertainty to the data. Proper attenuation of high power beams can be quite complex and generally requires multiple levels of attenuation provided by both reflective and absorptive filters. The first stages of attenuation need to be reflective attenuators, which in turn generate additional beams (reflections) that must be controlled or captured with beam dumps. It is not unusual to need four to six stages of attenuation to get a beam power to the level necessary to make camera measurements. It can be difficult to find space for this in the solar panel production modules.

In concert with several of the companies building photovoltaic manufacturing equipment, Photon has developed measurement instruments that are uniquely suited to making these measurements. The NanoScan slit-based profiler has the capability of measuring small beams directly with little or no attenuation, making it a logical choice for these types of analyses.