Detector documentation in PDF form: Datei:Detector Module.pdf
This module is designed to provide configurations of photodetectors for heterodyne detection. It is responsible for reading and recording the data that is returned from the atmosphere to the system (1).
Glossary of Terms
1. InGaAs: Indium Gallium Arsenide
This section includes the objectives and constraints of the Detector module (2).
1. Must be sensitive in the given range of optical wavelength
a. Should be constant or well defined within some wavelength range
2. Must be suitable for the range of optical power
3. Should have high quantum efficiency
This section describes the safety concerns of the Detector module, and suggestions for mitigating any possible risks.
The safety concerns of the detector module center around the chance of incoming radiation being redirected into the eyes of a bystander. As such, any radiation paths throughout the module must be completely sealed from the outside world. This includes both the backscattered path and the local oscillator’s path. In addition to this, all power outlets must be insulated and sealed, in order to prevent any accidental contact to high voltages by operators of the system.
High Level Overview
This section will discuss the main functions of the Control module and its constituent components.
Figure 1: System diagram of the Detector module
The detector module is separated into two major categories, the InGaAs Photodetector and the Photodetector Circuit. The photodetector circuit is only used if an amplifier is needed.
Low Level Information
This section includes an overview of the electronic components and circuitry that may be used in the detector module.
All information is specific to a single brand of InGaAs photodetector, and is simply a suggestion for the model of detector to use in the final design.
InGaAs Photodetector (JDSU (3)):
-Active diameter: 100µm -Responsivity: 0.75A/W -Dark current: 0.30A -Capacitance: 1.1pF -Bandwidth: 1.5GHz -Rise time: 250ps
-InGaAs Photodetector -Amplifier -Bandwidth: 2GHz
The use of photodetector circuit instead of an InGaAs photodetector alone has an advantage. It reduces parasitic capacitance, which allows the detector to operate on a wider laser bandwidth (4).
Figure 2: Dependency Map of Detector module; details in Table 1
- Power to operate the sensors and electronics
- Data to be processed by the Internal Control
- Local oscillator beam
- Backscattered beam
Table 1: Inputs and outputs of Detector module
This module is currently in the abstract definition phase.
Type description of testing on module here.
Software and power diagrams should be created as needed.
Detector module colour (Hex code): #666666
|Description of Work||Date||Author|
|Document started||27.07.15||Alan Yeh|
|Added High Level Overview, Low Level Overview, System Diagram, Dependency Map, Interfaces||27.07.15||Alan Yeh|
|General edits to grammar and style||31.07.15||Joshua Calafato, Katherine Maul, Frank Modruson IV, Alan Yeh|
|Added References||2.08.15||Alan Yeh|
|Minor format edits||12.08.15||Frank Modruson IV|
1. How does LiDAR works? (2015). In Lidar-UK.com. Retrieved August 2, 2015 from http://www.lidar-uk.com/how-lidar-works/
2. Photodetectors. (n.d.). In RP-Photonics.com. Retrieved August 2, 2015 from http://www.rp-photonics.com/photodetectors.html
3. High Speed InGaAs Photodetector Receptacle Modules. (2012, May 1). In JDSU.com. Retrieved August 2, 2015 from http://www.jdsu.com/ProductLiterature/etx100-ds-oc-ae.pdf
4. Koch, G., Beyon, J., Barnes, B., Petros, M., Yu, J., Amzajerdian, F., . . . Singh, U. (2007, November 20). High-energy 2μm Doppler lidar for wind measurements. In Opticalengineering.Spiedigitallibrary.org. Retrieved August 2, 2015 from http://opticalengineering.spiedigitallibrary.org/mobile/article.aspx?articleid=1088598