Physical Evolution of Gapless Microlens Array Technology on Camera Sensors in High Sensitivity Light Collection Efficiency

1. Early dilemma of “Fill Factor” on the sensor surface

The photodiode is flat, and the light projected by the lens must be completely captured:

• Traditional Gapped Microlens Array:
• Due to early semiconductor photolithography manufacturing process limitations, a physical process safety gap (Gap) of **0.15(\mu\text{m}) to 0.3(\mu\text{m}) must be retained between each micron-level hemispherical microlens;
• Fill Factor (Fill Factor, the ratio of the effective light-collecting area to the total pixel area) is usually only a pitiful 65% to 75%;
• This means that nearly 30% of the precious photons that hit the sensor surface directly hit the black dead space between the microlenses. Not only cannot they be converted into electronic signals, but stray reflections will also occur on the surface, causing a significant deterioration in the signal-to-noise ratio and weak low-contrast fog in the dark parts of the picture.

2. Gapless/Zero-Gap semiconductor hot-melt runner physical innovation

Sensor laboratories such as Canon and Sony conquered the microphotonics hot runner shaping process in the late 2000s:

• Micron-level hot melt seamless fusion (Thermal Reflow Process):
• By precisely controlling the surface tension and microflow characteristics of special optical polymer resin during baking;
• Make the edges of adjacent microlenses spontaneously merge into one during molding, and the microlens cross section evolves from the original isolated circle into a closely interlocked microscopic hexagonal honeycomb or square matrix (Honey-Comb/Square Packing);
• The micro gap is reduced to absolute zero (Zero Gap: (< 0.01,\mu\text{m}));
• Effective fill factor jumps to nearly 100%:
• The entire sensor surface becomes a complete and seamless microscopic compound eye optical light-trapping blanket;
• Any photon that hits the physical boundary of the sensor will accurately fall into the curvature funnel of a certain microlens and be 100% refracted and focused to the photodiode bullseye below.

3. Three major physical dividends of image quality brought to modern photographers

1. High sensitivity (High ISO) purity improved by nearly 1 stop (+1.0 EV):

• The improvement in light concentration efficiency directly allows the photosensitive element to collect more photoelectrons in weak light;
• Photon shot noise is significantly suppressed, and color noise in dark areas is greatly reduced in extreme low light from ISO 6400 to ISO 25600.

2. Large aperture lens (F1.2 / F1.4) real light transmission is unlocked:

• The incident angle of the edge light of the ultra-large aperture lens is extremely oblique; the gapless microlens increases the acceptance rate of oblique light at large angles by more than 30% by increasing the effective focusing diameter of the microlens, eliminating micro-mechanical shearing vignetting under ultra-large aperture.

3. It is possible to coexist with smaller pixels and ultra-high resolution:

• It is precisely because of the blessing of gapless technology that the pixel density of full-frame can safely and steadily climb from the early 12 million to 45 million or even 61 million without a signal-to-noise ratio collapse.

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