Improved contrast has enabled image recognition that produces clearer distinctions between black and white. Graphing and comparing the luminance levels of the resolution chart images shows that the MML-HR Series emphasizes differences in black/white luminance far more strongly than conventional MML products.

When using coaxial lighting for object recognition on a matte surface, light intensity may need to be increased in order to properly read the image because only a small amount of light returns from the surface to the lens. Boosting light intensity, however, also increases the brightness in the center of the image as the illumination from the lens is reflected. The ST and HR Series solve this problem using a hot spot reduction technique that vastly reduces the amount of reflection from the lens. This improves the uniformity of the field illuminance, even on matte surfaces.
Below are two images showing the results of character recognition on a rough microcomputer surface using conventional MML and MML-ST/HR products with coaxial lighting. The MML-ST/HR luminance graph shows superb uniformity between the luminance in the center of the image and the periphery, which is also evident in the sample image -- there is no highlight in the middle.

Pixel size, resolution limit frequency, F No correlation
The MML HR/ST Series features three optical designs for CCD cameras.

CCD camera: 5 million pixels; 3.45 μm/pix
Lens: Optical magnification of 2×WD 65 mm
Test chart: Resolving power of 5.563 μm (resolution of 179.6 lp/mm)