B Y: L E R A N F I R E R , D O H Y U N K I M , E R I C K L E I N B E R GC L I E N T : P R O F E S S O R J O N S I LV A

LIGHT DETECTION WITH ULTRA-HIGH DYNAMIC RANGE

Group 359/24/12

CLIENT REQUEST

• Need: Dr. Silva requested to design a light detection system with high signal to noise ratio.

Figure 1: A Typical Fluorescence Microscope System

BACKGROUND

• Fluorescence Microscopy is a recently developed technique that allows for the observation of conformational/functional changes in proteins.

Figure 2: Example of a Protein Viewable by Fluorescence Microscopy

SCOPE

• Must accurately amplify/filter signal 0.1% in magnitude relative to background (pA).• Must focus light to the diffraction limit onto the

PIN diode of electrical system. • Must keep photo diode cool to reduce noise.

Figure 3: The Three Main Parts of the Project

SPECIFICATIONS

Aspect Specification

Total System Cost < $1000

Size • PIN Diode must have active area close to the diffraction limit.

• PIN Diode must fit in the headstage (typically SM1 adaptor).

• Electrical and Peltier systems must also fit in the headstage.

• Headstage must fit C-mount

Power Source • Biasing is required to reduce noise, so a large power source is necessary. (Estimated 15-24V).

Light Focusing System • Must properly focus 600nm light to the diffraction limit. Ideally spot should match active area of PIN diode.

Temperature • Electrical system must be cooled to its ideal range, typically about -20°C.

Table 1: Specifications

TEAM ORGANIZATION

• Dohyun: PIN Diode Selection and Electrical System Design• PIN Diode• Integrating Amplifier/ Biasing• Bessel Filter• Current/Voltage Translator

• Leran: Fluorescence Focusing System Design• Lens Selection• Mounting Design

• Eric: Cooling System Design• Peltier Cooler

EXISTING SOLUTIONS

Photomax 200 by Dagan Corporation.• Cost: $10,850-13,900 depending on

configuration.• 4 Poles Bessel Filter • Up to 300 volt diode bias voltage• 2 Stages Peltier Cooled• Band Pass of Blue and Green Lights• Digitally filtered.

Figure 4: Photomax 200

PATENT AND LITERATURE

• Chris S. Gandhi, The Voltage-Clamp Fluorometry Technique, Methods Mol Biol. 2009 ;491 :213-31 18998096

• A.J. Horne and D. Fedida, Use of Voltage Clamp Fluorimetry in Understanding Potassium Channel Gating: A Review of Shaker Fluorescence Data, Can J Physiol Pharmacol. 2009 Jun;87(6):411-8

• Thomas Kugelstadt, Active Filter Design Techniques, Literature Number SLOA088, Excerpted from Op Amps for Everyone, Literature Number: SLOD006A

PATENT AND LITERATURE

US5054896: Continuously focusable microscope incorporating an afocal variator optical system

Figure 5: Afocal Variator Optical System

PRELIMINARY ANALYSIS

  Weight

PIN_10AP

PIN_10DP(I)/

SB

PIN_APD032

PIN_FD07

PIN_FD15

PIN_HR(s)008(L)

PIN-RD100(A

)Ultra Low

Noise10 10 10 10 10 10 10 10

Low Capacitance

8 0 0 10 10 10 10 10

Temperature Range

5 6 6 10 9 9 9 7

Responsivity at 600nm

9 7 8 6 6 6 7 9

Size of Diode Activation

Area

8 - - - - - - -

High Speed Circuit

4 0 0 2 2 2 2 2

  Total 193 200 282 287 287 296 296

Table 2: Pugh Chart for PIN Diode Selection

* Decision yet to be made

PRELIMINARY ANALYSIS

Filter Design and Selection• Bandpass Filter: 5-10 kHz

-Butterworth-Bessel-Schenk

• Bessel Filter: preserves the wave shape of filtered signals in the passband.

Figure 6: Bessel Filter Schematic

PRELIMINARY ANALYSIS

Actual Calculations• Center Frequency FM= 7.5KHz• Bandwidth B= 5kHz• Q= FM/B = 1.5• Center Gain Km = 1 (absolute value); Unity gain filter

• From the Coefficient of the 4th order Filter Tablea1 = 1.3617b1 = 0.6180 α = 1.2711 (at Q = 1.5)Fm1 = FM/ α = 5900.4 →Fm2 = FM* α = 9533.3C = 10 nF

PRELIMINARY ANALYSIS

Figure 7: 4th Order Bessel Bandpass Filter Designed with

Commercially Available Resistors and Capacitors

PRELIMINARY ANALYSIS

Singlet Lenses  Multi Element Lenses

Convex  Achromatic doublet

Plano-convex Achromatic doublet with matching aplanatic meniscus lens

Positive meniscus Symmetric lens pairs

Negative meniscus Cooke triplet

Plano concave  Double Gaussian

 Concave Custom

Singlet lenses are simple and easy to use, but a multi element lens system is favorable performance wise to avoid aberrations.

Table 3: Lens Types

PRELIMINARY ANALYSIS

Figure 8: Spherical (left) and Chromatic (right) Aberrations

Figure 9: Achromatic Doublet Focusing

Diffraction Spot Size Equation 1: d= 2.44*λ*fd - diameterf - focal lengthλ - wavelength

PRELIMINARY ANALYSIS

Thermal Interface Type Advantages Disadvantages

Solder • Highest thermal conductivity of 30-60W/m-K

• Eliminates need for fasteners

• Can only be used between metals.

Adhesive • Also eliminates need for fasteners.

• Somewhat more flexible in which materials they can thermally connect.

• Lower thermal conductivity compared to solder of only 1.5-8W/m-K

Grease • Common/cheap • Still requires fasteners.• Lower thermal

Conductivity of only .8-7.5W/m-K

Thermal Sheets • Very cheap/common • Low thermal conductivity of only 1.0-8.0 W/m-K

• Still requires fasteners.

Table 4: An Overview of Thermal Interfaces

DESIGN SCHEDULE

Date MilestoneSeptember 12 Began Preliminary ResearchSeptember 19 Primary Pugh Chart Evaluation for PIN

diode selection.

September 20 Bessel Filter DesignSeptember 21 Primary Pugh Chart of laser focusing

systems

September 23 Pugh chart of TEC methods/MountsSeptember 24 Preliminary Oral ReportSeptember 26 Preliminary Written Report September 26 First Simulation of Bessel Filter using

PSPICE.

September 28 Decide on best laser focusing systemSeptember 29 Begin Making Web PageSeptember 30 Design of Biasing Source to minimize

DC offset of the input.

October 1 Contact lenses manufacturersOctober 2 Decide on Specific TEC systemOctober 3 Web Page OperationalOctober 4 Design of Filtered Signal AmplifierOctober 5 Design of laser focusing systemOctober 7 Simulation of Complete Electrical

SystemOctober 8 Familiarize group with DesignSafeOctober 12 Contact TEC system manufactuerers.October 20 Begin working on Progress Oral and

Written Report

October 29 Progress Oral ReportOctober 31 Written ReportDecember 3/5 Final Oral Report, Written Report, and

Design Safe Analysis

Table 5: Schedule

PICTURE SOURCES

• Slide 2 Picture: The Voltage-Clamp Fluorometry Technique ,Chris S. Gandhi and Riccardo Olcese

• Slide 3 Picture: BME 301B, Dr. Cui’s Ion Channels lecture • Slide 4 Pictures: Lens from Thor Labs, PIN Diode from

http://www.shinebon.com/images/products/2011122165018597w1000h1000ushinebon/high-power-pin-diode.jpg, Peltier Cooler from http://www.dansdata.com/images/pelt/peltier400.jpg

• Slide 7 Picture: Dagan Corporation, http://www.dagan.com/photomax-200.htm

• Slide 10 Pictrure: US5054896, http://www.google.com/patents?id=g3sjAAAAEBAJ&pg=PA2&dq=optical+focusing+system+achromatic+doublet+lens&source=gbs_selected_pages&cad=4#v=onepage&q&f=false

• Slide 15 Figure 8 and 9: Lens, lens system, and optical aberrations http://www.cartage.org.lb/en/themes/sciences/physics/optics/Optical/Lens/Lens.htm