Hirose Kazuyoshi, Kamei Hiroki, Sugiyama Takahiro, Kurosaka Yoshitaka
Opt Express. 2020 Dec 7;28(25):37307-37321. doi: 10.1364/OE.403399.
3D structured illumination is important in high-speed 3D metrology where beam patterns are roughly categorized into multi-dot and fringe patterns. For example, large-scale multi-dot patterns are utilized for facial recognition in an iPhone X on the basis of an active stereo method, while fringe patterns are utilized in Grey code patterns or fringe projection profilometry including Fourier transform profilometry and the phase shifting profilometry, which is suitable for high-resolution measurement. Among these applications, the light sources include a combination of vertical-cavity surface-emitting lasers (VCSELs) and diffractive optical elements (DOEs), a projector, and so on. Recently, we demonstrated static arbitrary two-dimensional beam patterns without a zero-order beam from needle-tip sized integrable spatial-phase-modulating surface-emitting lasers (iPMSELs). Due to their compactness (they are one order of magnitude smaller than DOE), surface-emitting device, lack of zero-order beam, and ease of switching the beam patterns electrically, iPMSELs will be suitable as an ultra-compact light source for 3D metrology that not only downsizes the conventional light source but also contributes to 3D inspections in narrow spaces such as dental and endoscope examinations. In this context, we have examined two beam patterns (multi-dot and fringe) both without a zero-order beam by using the iPMSELs. In the former, we have demonstrated projection of large-scale dot patterns of more than 10,000 points, which is the same order of magnitude as points in a practical device from a 200×200-µm emitter. Since the emitter has approximately 1 mega scattering points, this structure enables 1-mega-pixel images in the wavenumber space, which are comparable to the images of a typical projector emitting several-mega-pixel images from several tens of centimeters. In the latter, we successfully shifted the fringe patterns, which is vital to applying the phase shifting profilometry, despite the superposition of the conjugate ±1st order beam patterns.
在高速三维计量中，3D结构光照很重要，其中光束模式大致可分为多点模式和条纹模式。例如，基于主动立体方法，大规模多点模式被用于iPhone X的面部识别，而条纹模式则用于格雷码模式或条纹投影轮廓术，包括傅里叶变换轮廓术和相移轮廓术，后者适用于高分辨率测量。在这些应用中，光源包括垂直腔面发射激光器（VCSEL）和衍射光学元件（DOE）的组合、投影仪等。最近，我们展示了来自针尖大小的可集成空间相位调制面发射激光器（iPMSEL）的无零级光束的静态任意二维光束模式。由于其紧凑性（比DOE小一个数量级）、面发射器件、无零级光束以及易于电切换光束模式，iPMSEL将适合作为三维计量的超紧凑光源，不仅可以缩小传统光源的尺寸，还有助于在牙科和内窥镜检查等狭窄空间进行三维检测。在这种情况下，我们使用iPMSEL研究了两种无零级光束的光束模式（多点和条纹）。在前者中，我们展示了从200×200 µm的发射器投影出超过10000个点的大规模点模式，这与实际设备中的点数处于同一数量级。由于发射器有大约100万个散射点，这种结构能够在波数空间中实现100万像素的图像，这与从几十厘米外发射几百万像素图像的典型投影仪的图像相当。在后者中，尽管存在共轭±1级光束模式的叠加，我们成功地移动了条纹模式，这对于应用相移轮廓术至关重要。
