| Segmented photodiodes (SPOT series) |
| Position sensing detectors (PSD) |
The SPOT series are photodetectors with a common cathode that are divided into either two (2) or four (4) separate active areas. They are available with either a 0.005″ or 0.0004″ clearly defined gap between adjacent elements, resulting in high response uniformity between elements. The SPOT series is ideal for very precise nulling or centering. Position information is obtained when the diameter of the light spot is larger than the space between the cells.
The spectral response range extends from 350 – 1100 nm. Notch or bandpass filters can be added to obtain specific spectral response. These detectors have excellent stability over time and temperature, fast response times necessary for high-speed or pulsed operation, and position resolutions better than 0.1 μm. The maximum recommended power density is 10 mW/cm² and the typical response uniformity for a 1 mm diameter is ±2%. The circuit (see datasheet) shows a typical bias and detection circuit configured for both bi-cells and quad-cells. For position calculations and further details, please refer to the “Photodiode Characteristics” section in this catalog.
Features
• High precision
• Excellent resolution
• High-speed response
• Ultra-low dark current
• Excellent reproduction/signal fidelity
• High stability over time and temperature
Applications
• Machine tool alignment
• Position measurements
• Guide beam centering
• Surface profiling
• Targeting
• Guidance systems