40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  40m Log  Not logged in ELOG logo
Entry  Thu Jul 14 20:24:32 2011, Nicole, Summary, SUS, Photosensor Head Lessons Photosensor_Head.jpg
    Reply  Fri Jul 15 01:11:21 2011, Koji, Summary, SUS, Photosensor Head Lessons 
       Reply  Fri Jul 15 14:23:30 2011, Nicole, Summary, SUS, Photosensor Head Lessons 
    Reply  Fri Jul 15 08:48:36 2011, Jamie, Summary, SUS, Photosensor Head Lessons 
       Reply  Fri Jul 15 14:29:30 2011, Nicole, Summary, SUS, Photosensor Head Lessons 
Message ID: 4969     Entry time: Thu Jul 14 20:24:32 2011     Reply to this: 4970   4971
Author: Nicole 
Type: Summary 
Category: SUS 
Subject: Photosensor Head Lessons 

Today I tested the photosensor head combination (2 Hamamatsu S5971 photodiodes and 1 Hamamatsu L9337 LED). I discovered that I had burnt out the LED and the photodiodes when I soldered them to the PCB board.

After looking up soldering information on Hamamatsu photodiodes, I learned that I need to solder at least 2 mm away from the head. I checked the pins of my burnt-out photodiodes and I had soldered 1.5 mm away from the head. To prevent this problem from happening again, Suresh suggested that I clip a lead onto photodiode/LED pin while I solder on connections to help dissipate some of the heat.

Today I was able to get a single photodiode (not attached to the PCB) to measure light emitted from an LED and I observed how voltage fluctuated as I moved the photodiode around the LED.

Suresh and Jamie also helped me to fix my photosensor head design (to make it more electrically-stable). Originally, I had planned to solder the LED and photodiodes onto a PCB and to mount that PCB to the front of a small metal Pomona Electronics box (with a whole cut out for the photodiodes and LED) using spacers, screws, and nuts.  However, the PCB I am using to solder on the LED and photodiodes has metal connections that may cause problems for the LED and photodiodes lying on the surface. Now, the plan is to have the LED and photodiodes mounted to the PCB with an insulatory PCB in between. Below is an explanatory picture.  I will determine the placement of the LED and photodiodes after making screws holes in the two PCBs to attach to the metal face of the box. I want to attach the screw holes first to make sure that the PCBs (and attached photosensor) are centered.



ELOG V3.1.3-