What is the size specification of a 0.23 inch optical waveguide module?
The 0.23 inch optical waveguide module typically measures 0.23 inches diagonally for its micro-OLED display panel, which translates to a physical die size of approximately 5.84 mm by 4.38 mm, depending on the aspect ratio. The overall module, including the waveguide combiner, housing, and optics, usually has dimensions around 20 mm by 15 mm by 8 mm, though this varies by manufacturer. For example, the 0.23 inch optical waveguide module from DisplayModule integrates a 0.23-inch OLED microdisplay with a resolution of 640x480 pixels, a pixel pitch of 8.1 micrometers, and a total module thickness of 6.5 mm. The waveguide itself is typically 1.5 mm to 2.0 mm thick, with a field of view (FOV) ranging from 20 to 30 degrees diagonal. These specifications are critical for AR smart glasses, where compactness and light weight—often under 10 grams for the module—are non-negotiable.
Physical dimensions and form factor are driven by the need to fit within slim eyewear frames. The micro-OLED panel in a 0.23 inch module has an active area of 5.84 mm x 4.38 mm for a 4:3 aspect ratio, common in industrial AR designs. The waveguide combiner, usually made of glass or polymer, adds 15 mm to 25 mm in length and 10 mm to 15 mm in width, with a thickness of 1.8 mm to 2.2 mm. The entire assembly, including the micro-OLED, driver IC, and flex cable, occupies a volume of roughly 2.5 cubic centimeters. For instance, the Sony ECX335A microdisplay, often used in such modules, has a 0.23 inch diagonal with a resolution of 640x400 pixels, a pixel pitch of 8.0 micrometers, and a module size of 16.5 mm x 12.5 mm x 5.8 mm. This allows for a 24-degree diagonal FOV with a 15 mm eye relief, typical for monocular AR systems.
Optical specifications are tightly coupled with size. The waveguide’s exit pupil diameter is usually 4 mm to 6 mm, with an eye relief of 14 mm to 18 mm. The module’s total track length—from the micro-OLED surface to the waveguide exit—is 8 mm to 12 mm. Luminance levels reach 3000 to 5000 nits at the micro-OLED, but after waveguide coupling efficiency (typically 10% to 20%), the perceived brightness is 300 to 1000 nits. Contrast ratios exceed 10,000:1 for OLED-based modules. The waveguide’s diffraction grating, often a surface relief grating with a period of 300 to 400 nanometers, has a thickness of 0.1 to 0.5 micrometers, adding negligible bulk. These numbers are backed by datasheets from manufacturers like Lumus and WaveOptics, which report similar footprints for their 0.23 inch modules.
Weight and materials are another dimension of size specification. The micro-OLED itself weighs 0.3 to 0.5 grams. The waveguide combiner, if made from high-index glass (n=1.7 to 2.0), adds 1.5 to 3.0 grams. The housing, typically aluminum or plastic, contributes 2.0 to 4.0 grams. Total module weight falls between 4.0 and 8.0 grams. For example, the Kopin P1270 module, which uses a 0.23 inch OLED, has a weight of 5.5 grams and dimensions of 18.0 mm x 14.0 mm x 7.2 mm. Thermal management is also size-dependent: the module’s power consumption of 150 to 250 milliwatts requires a heat spreader of 0.3 mm to 0.5 mm thickness, often integrated into the housing.
Electrical interface and connector size affect the overall module dimensions. The flex cable is typically 0.3 mm to 0.5 mm thick and 8 mm to 12 mm wide, with a length of 30 mm to 50 mm for routing to the driver board. The connector, often a 0.5 mm pitch FPC, adds 2 mm to 3 mm to the module’s width. The driver IC, if integrated, measures 3 mm x 3 mm x 0.6 mm. These elements push the total module footprint to 20 mm x 15 mm x 8 mm, as seen in the 0.23 inch optical waveguide module from DisplayModule, which includes a 640x480 micro-OLED, waveguide, and driver in a single package.
Comparative data across manufacturers shows consistency. The table below summarizes key size specs for three common 0.23 inch modules:
| Parameter | DisplayModule DMGTX0023WGNA | Sony ECX335A | Kopin P1270 |
|---|---|---|---|
| Display diagonal | 0.23 inch | 0.23 inch | 0.23 inch |
| Resolution | 640x480 | 640x400 | 640x480 |
| Pixel pitch | 8.1 µm | 8.0 µm | 8.5 µm |
| Module dimensions (mm) | 18.5 x 14.2 x 6.5 | 16.5 x 12.5 x 5.8 | 18.0 x 14.0 x 7.2 |
| Waveguide thickness | 1.8 mm | 1.6 mm | 2.0 mm |
| FOV diagonal | 25 degrees | 24 degrees | 26 degrees |
| Weight | 5.0 g | 4.5 g | 5.5 g |
| Luminance (micro-OLED) | 4000 nits | 3500 nits | 5000 nits |
Application-driven size constraints further refine these numbers. For AR smart glasses, the module must fit within a temple arm that is 5 mm to 8 mm thick and 15 mm to 20 mm wide. The waveguide’s length (20 mm to 25 mm) determines how far it extends from the lens. The eye relief of 15 mm to 18 mm ensures the module does not interfere with prescription lenses. The exit pupil diameter of 5 mm to 6 mm allows for a 10 mm to 12 mm eye box, which is critical for comfortable viewing. These dimensions are validated by optical simulations showing that a 0.23 inch module with a 25-degree FOV requires a waveguide length of 22 mm and a width of 14 mm, matching the 0.23 inch optical waveguide module’s datasheet.
Thermal and mechanical tolerances are also size-related. The module’s operating temperature range of -20°C to 70°C requires a housing that can dissipate 0.5 to 1.0 watt of heat. The coefficient of thermal expansion (CTE) of the waveguide glass (8.5 ppm/°C for Schott D263T) must match the housing material to avoid stress. The module’s mounting holes are typically 1.5 mm in diameter, spaced 15 mm apart, with a tolerance of ±0.1 mm. The flex cable’s bend radius of 3 mm to 5 mm ensures it fits within the temple arm. These mechanical specs are critical for integration into consumer AR devices like the Vuzix M400 or Epson Moverio, which use similar 0.23 inch modules.
Optical efficiency and size trade-offs are worth noting. The waveguide’s coupling efficiency of 12% to 18% means the micro-OLED must be bright, but the module’s small size limits heat dissipation. The 0.23 inch module’s 8.1 µm pixel pitch provides a resolution of 78 pixels per degree (PPD) at a 25-degree FOV, which is sharp for text rendering. The modulation transfer function (MTF) at 30 cycles per degree is 0.4 to 0.6, depending on the waveguide design. The module’s overall size is a compromise between FOV, resolution, and weight—larger waveguides offer wider FOV but add bulk. For example, a 0.23 inch module with a 30-degree FOV would require a waveguide length of 28 mm, increasing weight by 1.5 grams.
Manufacturing tolerances affect the final size specifications. The micro-OLED’s alignment to the waveguide must be within ±5 micrometers in the x-y plane and ±10 micrometers in the z-axis. The waveguide’s grating depth is controlled to within ±10 nanometers. These tolerances result in a module-to-module variation of ±0.2 mm in length and ±0.1 mm in thickness. The 0.23 inch optical waveguide module from DisplayModule is specified with a length tolerance of ±0.15 mm, width of ±0.1 mm, and thickness of ±0.05 mm, ensuring consistent fit in AR frames.
Power consumption and size correlation is another factor. The micro-OLED draws 80 to 120 milliwatts, the driver IC uses 30 to 50 milliwatts, and the waveguide’s heating element (if any) adds 10 to 20 milliwatts. Total power is 150 to 250 milliwatts, which requires a battery of 300 to 500 milliampere-hours for 2 to 3 hours of operation. The module’s size allows integration into a 6 mm thick temple arm, as seen in commercial AR glasses like the Rokid Air or Nreal Light, which use similar 0.23 inch modules.
Environmental and durability specs are tied to size. The module’s ingress protection rating of IP54 requires a housing that is 0.5 mm to 1.0 mm thick, adding 0.5 grams to the weight. The waveguide’s scratch resistance is achieved with a 0.1 mm thick hard coating. The module’s vibration resistance of 10 G at 10 to 500 Hz requires a mounting bracket that adds 1 mm to the width. These factors ensure the module survives drops from 1.5 meters, as specified in the 0.23 inch optical waveguide module’s datasheet.