對於塑膠光學鏡片之超精密加工模仁而言，線上之表面量測技術可以避免切削表面受到損傷，以He-Ne 雷射搭配1 × 15陣列二極體感測器，獲致無電解鎳及鋁工件表面反射之光散射效應，可預測超精密加工之工件之表面粗糙度。結果顯示光散射分佈效應與工件之表面粗糙度成正比，散射能量的總和與入射光能量的比值也越大，工件表面粗糙度與進給率呈正比，光散射亦與表面粗糙度呈正向關係。

An in-situ measurement technique to gauge surface roughness of ultra-
precision machining with optical characteristic effects is critical and is
achieved without a probe to avoid contact damage on the surface. Because
the plastic lens molding reprints the roughness from the mold core
fabricated by machining, the tool marks induce a poor surface on the plastic lens. The machined surface reflects the input light from an He-Ne laser of the wavelength of 632.8 nanometers. Several samples made of
electrolyte-less nickel and aluminum with different surface roughnesses
were created by varying the feed rate of ultra-precision machining, and
their surface roughnesses were measured with the red He-Ne laser. A
1 × 15 photo-diode array with a pitch of 1.6 mm was constructed to measure
the distribution of the optical scattering effect under the He-Ne laser
light source. The results show that the increased surface roughness causes
a wider light scattering distribution. In addition, the light scattering effect from the machined surface is proportional to roughness. Using the ratio of the main and side measuring channels of the photo-diode array is a suitable approach to construct the relationship between the light scattering and surface roughness. The increased ratio means the surface roughness decreases.The ratio of reflective specular light intensity to that behind the sub-channel is clearly related to the surface roughness. The curve fitting is close to the experimental results subject to the larger value of R2.Therefore, the laser and the photodiode array predict the roughnesses of the ultra-precision machined surfaces of aluminum well. The online roughness measurement technique using the reflected light scattering effect from an ultra-precision machined surface is constructed in this study.