Modular led array light sources of high density

A modular array light source unit, preferably comprising a plurality of LED solid state array modules, is provided. Modules can adjoin one another to provide a large area, high intensity, high density array. Preferably, in each module there is provided a linear or rectangular array of LED groups in which the density of the LED chips at ends or edges of the modules adjacent to other modules is higher to provide improved uniformity over the illuminated area between modules in terms of radiation intensity. Certain arrangements of LED clusters are provided which cause, reduce or eliminate the discontinuity or slope in radiation intensity due to edge or wall effects caused by the spacing of the LED chips from edges of the substrate / housing of each module. These arrangements are advantageous for hermetically sealed LED array modules which, for example, require a minimum wall thickness for effective sealing.