The LC Film (Light-Control Film) or collimator film is primarily used to enhance the visibility of test object outlines in transmitted light, ensuring consistent product quality and reducing the rejection of defective parts.
The fundamental structure of the LC Film consists of numerous highly precise lamellae, similar to a venetian blind. These lamellae are distributed across the entire surface. The purpose of these prisms is to either reflect or absorb light with undesirable angles of incidence (>30°). This means that while the actual light power reaching the test object is reduced, only light from a defined emission angle arrives. The transmission in the visible range is approximately 68%, while the LC Films are blocking and unsuitable for the infrared and UV range.
The LC Film is particularly suitable for the FLDL-TP and FLFL backlight series. The space-saving installation of the film offers a cost-effective option compared to telecentric illuminations for users who do not require a 100% parallel optical path.
The Light Control Film used by FALCON reduces the angle of incidence of light to 30° from the vertical axis. This value has been found to be an optimal compromise between light power and angle of incidence. Telecentric illuminations are currently being developed for more precise measurements.
The following image illustrates how stray light from unwanted emission angles illuminates the slanted edges of the test object, thereby complicating measurement: