Profile projectors are widely used 2D dimensional measuring tools, commonly applied in mold processing, hardware parts, and electronic product inspections. While optical imaging is the core of profile projectors, many overlook the significant impact the light source has on measurement results. The uniformity of illumination directly affects the clarity of the projected image and the accuracy of measurements.
This article shares several common and practical light source optimization methods to help better understand how to improve the image quality of profile projectors.
Diffuse Reflection Devices: Achieving More Even Light Distribution
Many traditional profile projectors use halogen lamps or LED light sources. These light sources often emit concentrated beams, causing bright spots in the image center and weaker light at the edges. Such “hot spots” affect contour edge observation and measurement accuracy.
To address this, profile projectors usually install diffuser plates or translucent diffusion films. These components scatter concentrated light into a uniform, diffuse illumination. As a result, light distribution on the projection screen becomes more even, reducing overly bright centers and enhancing edge brightness.
For example, a user measuring small parts initially experienced unclear edge details due to excessive center brightness. After adding a diffuser, the overall brightness distribution became more uniform, making measurement easier and repeatability improved.
Light Homogenizer: Turning Point Light Sources into “Area” Light Sources
With the increasing use of LED lights, although they provide high brightness and long life, their point-like emission causes uneven light spots in images.
To solve this, profile projectors use light homogenizers—optical elements that evenly diffuse point light into smooth, uniform area light. Usually placed between the light source and the lens, the homogenizer “flattens” uneven light intensity.
In practical applications, such as plastic part inspections, adding a homogenizer significantly reduces gray-scale variation, stabilizes edge recognition, and allows automated measurement software to process images more accurately.
Optimizing Light Source Arrangement and Angle to Reduce Shadows
Profile projectors often face complex workpieces with grooves or steps, where single-direction illumination can cause shadows that affect contour imaging.
To avoid this, multi-point light source designs, such as ring-shaped LED arrays or a combination of coaxial and oblique lighting, are used. Illuminating from multiple angles effectively reduces shadows and occlusions.
Additionally, some devices allow adjustment of the illumination angle to ensure the light hits the workpiece surface as perpendicularly as possible, minimizing distortion of the light spot. For instance, when measuring gear inner holes, adjusting the light angle clarifies inner edges and improves measurement accuracy.
Conclusion
Although the light source system is a fundamental part of profile projectors, it greatly influences the quality of measurement images. Using diffuse reflection devices, homogenizers, and optimized light layouts can make light distribution more uniform, reduce hotspots and shadows, and yield clearer, more stable projection images.
These optimizations are not only mature design ideas but also key to enhancing measurement experience and reliability. In the future, with technological advancement, intelligent light source adjustment combined with digital image processing will better meet diverse measurement demands.