3D Sensing Defining Requirements for Electrical Test of Optical Devices
3D sensing augments a camera's object & facial recognition.
3D sensing is a depth sensing technology that augments camera capabilities for facial and object recognition in augmented reality, gaming, autonomous driving and a wide range of applications.
- One way to sense 3D is using structured light. Coherent infrared light is transmitted onto an object with a structured pattern. The reflected light can be decoded to construct a 3D image.
- Another way to sense 3D is to use Time of Flight (ToF). A light source transmits a series of infrared light and the photon phase difference to the light bounced off an object is used to sense the proximity of an object.
Diode-based optical devices enable 3D sensing.
Diode-based devices such as laser diodes, high brightness LEDs (HBLED), and photodiodes (PD) are key optical devices that enable 3D sensing.
- Laser diodes are capable of outputting a narrow and coherent light beam. Two common types of laser diodes are edge emitter laser (EEL) and the fast-growing VCSEL (vertical cavity surface emitting laser). VCSEL combines the advantage of low cost manufacturability, optical efficiency, temperature stability, and large 2D arrays for increased power. EEL operates at a higher frequency that can travel hundreds of miles without loss in a fiber medium commonly for optical communication.
- HBLEDs or LEDs disperse incoherent light in a wide pattern. They are the most efficient source of high quality white light, hence great for illumination. Efficiency droop, limited modulation capability, and resolution make them only suitable for some applications.
- PDs detect and convert light into current. Very sensitive instruments for low PD current measurement are required to characterize the full range light intensity of the light source properly.
Keithley instruments perform electrical testing on diode-based devices.
Wavelength stability over the entire operating temperature of these devices is critical to maintaining precision and minimize noise in received signals. Electrical efficiency measurement through precision trigger and synchronization of pulse width and duty cycle further optimize the required intensity and resolution of illumination. These directly impact the heat dissipation, power consumption, and battery life of the end system.
Keithley has an extensive portfolio of instruments for electrical tests, including light intensity, forward voltage, lasing threshold current, quantum efficiency, dark current, the presence of “kink” or kink test, slope efficiency, thermistor resistance, temperature, capacitance, and the full spectrum of L-I-V pulse testing of laser diodes and HBLEDs.
Learn from Keithley experts.
The application engineers at Keithley offer white papers, application notes and blogs on these topics and more.
Watch our webinar and learn 10 test methods for a variety of devices, including those used for 3D sensing.
Get our application note, Laser Diode Array Test for 3D Sensing.
Get our application note, Enhancing Trigger Synchronization for High Volume Production Testing of VCSELs.
This white paper offers an overview on using an integrating sphere to measure the optical power of radiant sources in a production environment.
This white paper explores how to eliminate sources of error when pulse testing VCSELs or laser diodes and how to obtain shorter test times, more accurate results, and lower reject rates.
This application note offers techniques to increase throughput, maximize synchronization, and reduce overhead in laser diode production test.
Series 2600B SMU
The best system for laser diode testing, Series 2600B instruments boast high speed and high accuracy for both pulse current sourcing and voltage-current monitoring for highly automated and synchronized production test.
DMM7510 7½-Digit Graphical Sampling Multimeter
Keithley's DMM7510 combines a precision, high-resolution digital multimeter (DMM) for thermistor resistance and temperature measurement of a laser diode module with a graphical touchscreen display and high-speed, high-resolution digitizer with pA-level sensitivity and 1Msample/s sampling for dark current to full short pulses of lasing power.
2510 and 2510-AT TEC Instruments
Keithley's 2510 and 2510-AT TEC SourceMeter SMU Instruments regulate the operation of a laser diode module’s thermo-electric cooler to ensure accurate, tight temperature control of the device under test.
2651A High Power SMU Max 50A
Keithley’s 2651A High Power SourceMeter SMU Instrument offers up to 2000W of pulsed current (±40V, ±50A) to improve productivity in HBLED and optical device characterization and testing.
2401 Low Cost SMU 20V, 1A, 20W
Keithley 2400 Series SourceMeter SMU instruments offer high speed and high accuracy for both current sourcing and voltage-current monitoring of laser diode modules and photodiode current.
6485 5½-Digit Picoammeter
For dark current to full lasing power, Keithley's cost-effective 6485 Picoammeter can measure photodiode currents from 20 fA to 20 mA at speeds up to 1000 readings per second.