Phase-measuring profilometry is an accurate and effective technique for performing three-dimensional (3D) shape and deformation measurements of diffuse objects by fringe projection. However, phase analysis cannot be performed in underexposed or overexposed areas of the detector when an object with wide reflectance is measured. A novel intensity range extension method using a digital micromirror device (DMD) camera is proposed. In the optics of the DMD camera, each pixel of the CCD corresponds exactly to each mirror of the DMD. The phase-shifted fringe patterns with high contrast can be easily captured by programming an inverse intensity pattern that depends on the reflectance of the object. Our method can provide a wider intensity range and higher accuracy for 3D shape measurement than other conventional methods in both underexposed and overexposed areas. The measurements of a replica of a metallic art object and a flat plane are analyzed experimentally to verify the effectiveness of our method. In the experiment, the percentage of invalid points due to underexposure and overexposure can be reduced from 20% to 1%.

A camera based on the digital micromirror device (DMD) technology has been previously developed. In this optical system, the correspondence of each mirror of the DMD to each pixel of the CCD cannot readily be done since the pixel sizes of the DMD and the CCD are very small. An accurate pixel-to-pixel correspondence adjustment in the DMD camera by means of the phase-shifting moiré method is proposed. To perform high accurate adjustment of the optical system, the phase distribution of a moiré fringe pattern is analyzed when the CCD pixels and the DMD mirrors have a mismatch and∕or misalignment with each other. This technique does not need a complicated setting or complex image processing to generate the moiré fringe pattern, and it needs only one captured image. In the adjustment experiment, the proposed method provided very accurate adjustment whose error was less than $1/25\mathrm{pixel}$. An experiment of phase analysis to demonstrate the usefulness was performed.

High-speed height measurement is required in industrial fields for analyzing the behavior of a breaking object, a vibrating object or a rotating object. A shape measurement performed using a phase-shifting method can measure the shape with high spatial resolution because the coordinates can be obtained pixel by pixel. A light-source-stepping method (LSSM) that uses a linear LED array by means of a whole-space tabulation method (WSTM) has been proposed. Accurate shape measurement can be performed using this method. The response speed of the LED array is greater than 12 kHz. In this paper, height measurement is performed using WSTM and LSSM with a linear LED array and a high-speed camera. It was verified that the response speed of the linear LED is greater than 200 kHz. The phase shifting was performed at 12 kHz, and the height measurement of the vibrating woofer was performed at 4 kHz using a 3-step phase-shifting method.

In phase-shifting digital holographic interferometry for measuring the displacement distribution of an object, holograms and reconstructed images have speckle noise, and they cause large errors in the calculation of the displacement analysis. In order to reduce the effect of speckle noise and hence to increase the sensitivity of the measurement of the displacement, we previously proposed a method using windowed holograms. In this paper, we propose a new method for averaging the obtained phase-difference values. Many phase-difference values at a point of the reconstructed image obtained with different windows for a hologram are averaged with weights. In order to check the effect on accuracy, the number $n$ of windows used for averaging is varied. The weight, which is the $m$’th power of the absolute value of the complex amplitude of the reconstructed object, is also varied. As a result, when $n$ becomes larger, the standard deviation of the errors becomes smaller. When the power $m$ is 2, the error becomes a minimum. The standard deviation of the errors in the case of a flat plate with 316-nm out-of-plane displacement is $88pm$ when $n=1024$ and $m=2$.