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Thin Film Coatings
Like a variety of optical products such as cameras and semiconductor fabricating equipment, Nikon has also played the leading role in thin film coatings.
Nikon recently developed the new coating process technology, called the Automated Deposition System, for producing multi-layered thin film coatings.
The ADS is characterized by the ingenious process in which the system's built-in inspection mechanism allows the thickness of a coating layer to be measured and then takes the measured outcome into account to determine the thickness of the next coating layer for correction.
This process repeats itself ceaselessly until reaching the given number of coating layers.
As the ADS observes coating operation and verifies accuracy of each layer's coating thickness, it is excellent in manufacturing filters that can produce transmittance characteristics within tolerance limits of customer-specified values.
Hence, it fits into crafting gain flattening filters needed to produce an individually-specified transmittance characteristic curve and also edge filters required to have flat transmittance characteristics.
The ADS' ability to proceed with coating without a work stoppage can make it possible to shorten lead times, and customized coatings can also be achieved on as few trial runs as possible.
Unlike the traditional depositing one, the use of the sputtering coating method makes for keeping layer interfaces smooth and flat, ensuring that a total loss is minimal.
Thermal stability is very good as it stays within a range of 1pm/C°(degree).
| Wavelength range | 1530 to 1562 nm |
|---|---|
| Error function | +/-0.3 dB |
| Minimum insertion loss |  0.1 dB |
| Polarization dependent loss | 0.1 dB |
The error function of Nikon flattening filters can fall in the range of +0.3dB and -0.3dB. The graph at the top of the page compares the theoretical and measured performance of a gain flattening filter across its optical performance domain. The black dots depict the theoretical values while the red line shows the measured ones. Nikon GFFs also work in S-Band and L-Band windows. Thanks to the ADS capability, orders usually ship in two weeks.
| Pass band | 1400 to 1495 nm |
|---|---|
| Minimum insertion loss in pass band |  -0.2 dB |
| Rejection band | 1505 to 1650 nm |
| Minimum insertion loss in rejection band | -25 dB |
| Polarization dependent loss (PDL) | 0.1 dB |
Attenuation can be controlled at -0.2 dB at any point on the coated surface. The graph at the top of the page illustrates the measured performance characteristic of SWPF edge filter with very steep cutoff slope. The bold blue line depicts the exaggerated performance of the filter.