Abstract: An optical sensor enables a level of reflective fluid to be detected. The optical sensor includes a prism mounted at one end of a housing. The prism has an exterior surface that is parallel to the end of the housing and a width that corresponds to a width of the end of the housing. A photoemitter and a photodetector are mounted at another end of the housing to enable light emitted by the photoemitter to be reflected by the prism when the prism contacts reflective fluid and to enable light emitted by the photoemitter to pass out of the sensor when the prism is in contact with air.

Abstract: An optical sensor enables a level of reflective fluid to be detected. The optical sensor includes a prism mounted at one end of a housing. The prism has an exterior surface that is parallel to the end of the housing and a width that corresponds to a width of the end of the housing. A photoemitter and a photodetector are mounted at another end of the housing to enable light emitted by the photoemitter to be reflected by the prism when the prism contacts reflective fluid and to enable light emitted by the photoemitter to pass out of the sensor when the prism is in contact with air.

Abstract: A method of thermal transfer printing on a substrate includes the steps of determining, on a pixel by pixel basis, where colorant is to be located on the substrate; applying an image-enhancing precoat to each pixel where colorant is to be located, as well as to at least one immediately adjacent pixel; and depositing a colorant onto the precoated predetermined pixels. The precoating that is applied to the immediately adjacent pixels helps retain the precoating to the substrate, among other advantages. A second method, for printing on a rough substrate, includes steps of applying an image enhancing precoat so as to form bridges across valleys of said rough surface; and subsequently depositing a colorant onto the precoat. A third printing method includes the steps of applying a precoat to the substrate which has one or more voids defined therein; and depositing a colorant onto the precoat so as to bridge over the voids in the precoat. Related systems and printed products are also disclosed.