A digital micromirror device (DMD) is a micro-opto-electronic device that incorporates mirrors and static random-access memory circuitry in one package. This technology allows fast, efficient spatial light modulation for projectors, lithography, and machine vision systems.
High Resolution
Since its introduction, digital micromirror device (DMD) technology has revolutionized many optical applications. It is a key enabler of today’s cost-effective near-IR spectrometers.
DMD chips are electrical input, optical output micro-opto-electromechanical system spatial light modulators that provide high speed and efficient control of a light pattern. Each mirror in a DMD is controlled independently and can be tilted to reflect light in one of two directions (+ or – 20deg optically).
Each pixel in the image is generated by changing the state of each mirror. The incident angle at twice the mirror tilt angle determines the DMD’s diffraction envelope. As a result, the major diffraction orders are located off-axis from the optical axis, which can compromise hologram reconstruction quality. To reduce the impact, a dmd sensor installer of a DMD sensor can adjust the optical setup to allow for a slight tolerance in the mirror rotation angle.
Fast Response
DMDs use a two-dimensional array of micromirrors with an individual tilt degree of freedom. Each mirror can be in one of two states: on or off. When a hologram is loaded on the DMD, only the micromirrors in the on state will contribute to the diffraction field.
Diffraction patterns can be generated at high speeds and with high precision. This makes DMDs a promising alternative to Liquid-crystal Spatial Light Modulators for producing dynamically controllable structured light fields.
The DMD and the readout device work together to sample the data continuously. During this cycle, the computer generates a measurement matrix phi, and the DMD presents it to the CNT detector by changing its mirrors to either on or off. Then the data from the detector and readout devices are saved in digital form and transmitted to a computer for processing.
Low Inertia
As each mirror can be controlled independently, the DMD can change its position in a small range of motion. This allows for a very high resolution without requiring multiple mirrors to be moved simultaneously.
This low inertia is because the micromirrors are stacked together on a single plane, which makes the actuation mechanism much simpler than other devices that use hidden hinges. This makes DMDs more energy-efficient and cost-effective.
In addition, the landing hinge yoke is shorter than the mirror element, generating less sticking torque. As a result, the DMD requires a lower reset voltage than other hidden hinge DMDs. This is especially advantageous for applications requiring large resolution because it avoids the ” twinkling ” problem caused by mirrors stuck in the on state for too long.
Wide Range of Applications
The ability to electronically steer the direction of a beam of light has many practical applications. With advances in micro/nano-fabrication technologies, many micromirrors can be integrated into an array on a single chip and steered by electrical actuation.
The most common use of DMDs is for projectors in single-DMD color-sequential displays and three-DMD business projection systems. In the three-DMD configuration, each DMD modulates the brightness of one component color of RGB light from LED or laser sources. The resulting composite duty cycle is lower than single-DMD displays, which helps deliver higher brightness for brighter projectors.
TI’s DMD technology is also used in other optical applications, including 3D scanning or metrology with structured light, augmented reality, medical instruments, and spectroscopy. This enables optical solutions that disrupt existing end equipment or create new markets with innovative functionality and efficiency.
Cost-Effective
Digital micromirror device sensors are more cost-effective than other spatial light modulators, such as liquid crystal displays (LC-SLM). They can be manufactured in large volumes and offer high-resolution, low-power operation. This makes them suitable for many applications, including projection systems, medical imaging, and augmented reality.
The diffraction field of the DMD depends on both the incident angle and the tilting angle. The main diffraction order is located on the optical axis and can be accurately determined using Equation (25) for a 1D DMD.
Each mirror can be in the +12deg or -12deg state in a DMD by applying a reset pulse. Grayscale patterns can be displayed by controlling the on/off duty cycle of each mirror. This is made possible by the small hinge angle of each mirror, which can be precisely stopped against two spring tips.
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