Project Scope
Project: “Light Detection with Ultra-high Dynamic Range”
By: Dohyun Kim, Leran Firer, and Eric Kleinberg (Group 35)
Client: Dr. Jon Silva, ([email protected])
Project Theme
PIN photodiodes produce a very small current in response to light and this current can be accurately measured by using a commercially available integrating amplifier. The signals from such a system have very high dynamic range. We will design a system that reduces noise from the laser light signal using a filtering circuit, a cooling system to reduce noise of the filtering circuit, and an optical focusing system to focus the laser onto the PIN diode. Such a system should be useful in detecting changes in protein activity via fluorescence imaging. This is useful from a BME context in the study of an assortment of protein activity, including but not limited to: enzymes, channel proteins, ???
Project Goals
1. Filtering System (Electronics)
a. Design electrical system using a Pin Diode of our choice that is capable of accurately amplifying a signal 0.1% in magnitude relative to the background noise, a feat that manufacturers claim to be unreasonably difficult, but which Professor Silva has apparently demonstrated. Must condition signal to have high signal to noise ratio. Some possible design directions/inspirations include: reducing size/capacitance, biasing by -15 V, implementation of variable resistance to control current into OP Amp. Target bandwidth for the filter should be 5-10kHz. Client recommended specifically using an Analog Bessel Filter.
b. Biasing will likely be done with some sort of power source (ex: battery). The power source is not constrained by the headstage as wires can be lead through the headstage.
Figure1. Head Stage of the Electrical System
2. Cooling System
a. The Pin Diode system produces a cleaner signal at lower temperatures. As such, client has requested a cooling system. He has suggested implementation of a Peltier type system (0 ~ -20oc) or similar such systems, though we are free to design a custom system if necessary. The chosen system should fit the head stage.
3. Light Focusing System
a. Client has requested design of an improved optical focusing system. Calculation is required for ideal area of focused light spot: specifically, there is a tradeoff between how much light reaches the PIN Diode versus noise. Client has requested either a custom focusing system, or off the shelf equivalent if cost is reasonable.
Overall Requirements
Cost
<$1000 for entire system
Size
Headstage must fit C-mount. Photodiode and cooling system must fit any adaptor we use (client suggested SM1). Focusing system can be as big as necessary, but should be as small as possible to fit microscope.
Power Source Requirements
Client recommended a large battery, but noted that this decision is dependent on the resistor used in filtration (nA current).
Project: “Light Detection with Ultra-high Dynamic Range”
By: Dohyun Kim, Leran Firer, and Eric Kleinberg (Group 35)
Client: Dr. Jon Silva, ([email protected])
Project Theme
PIN photodiodes produce a very small current in response to light and this current can be accurately measured by using a commercially available integrating amplifier. The signals from such a system have very high dynamic range. We will design a system that reduces noise from the laser light signal using a filtering circuit, a cooling system to reduce noise of the filtering circuit, and an optical focusing system to focus the laser onto the PIN diode. Such a system should be useful in detecting changes in protein activity via fluorescence imaging. This is useful from a BME context in the study of an assortment of protein activity, including but not limited to: enzymes, channel proteins, ???
Project Goals
1. Filtering System (Electronics)
a. Design electrical system using a Pin Diode of our choice that is capable of accurately amplifying a signal 0.1% in magnitude relative to the background noise, a feat that manufacturers claim to be unreasonably difficult, but which Professor Silva has apparently demonstrated. Must condition signal to have high signal to noise ratio. Some possible design directions/inspirations include: reducing size/capacitance, biasing by -15 V, implementation of variable resistance to control current into OP Amp. Target bandwidth for the filter should be 5-10kHz. Client recommended specifically using an Analog Bessel Filter.
b. Biasing will likely be done with some sort of power source (ex: battery). The power source is not constrained by the headstage as wires can be lead through the headstage.
Figure1. Head Stage of the Electrical System
2. Cooling System
a. The Pin Diode system produces a cleaner signal at lower temperatures. As such, client has requested a cooling system. He has suggested implementation of a Peltier type system (0 ~ -20oc) or similar such systems, though we are free to design a custom system if necessary. The chosen system should fit the head stage.
3. Light Focusing System
a. Client has requested design of an improved optical focusing system. Calculation is required for ideal area of focused light spot: specifically, there is a tradeoff between how much light reaches the PIN Diode versus noise. Client has requested either a custom focusing system, or off the shelf equivalent if cost is reasonable.
Overall Requirements
Cost
<$1000 for entire system
Size
Headstage must fit C-mount. Photodiode and cooling system must fit any adaptor we use (client suggested SM1). Focusing system can be as big as necessary, but should be as small as possible to fit microscope.
Power Source Requirements
Client recommended a large battery, but noted that this decision is dependent on the resistor used in filtration (nA current).