So, all this madness started when I replyed in this thread ==> My ROTJ Fett build WIP. It was OK at first, but while I did my second reply...
Then I looked at the Supertrooper Documentation - Helmet image, more exactly at the '3 lamps-white'...
...then again at the first image and again the Supertrooper page and again the first image, and then... it hit me! I did a quick search on the net and I got this term: GRAIN OF WHEAT. This is the name of the light bulbs (diameter varying from 1mm to 3mm, or bigger) used by hobbyist, in some fields of the industry and even for medical or optical instruments; I'm pretty sure they used these lamps in the Star Wars studio scale models too.
3mm diameter/7mm length GoW light bulb.
2mm diameter/6mm length GoW light bulb.
1mm diameter/3.5mm length GoW light bulb.
And some images of older (I'm not sure about how old are these) GoW light bulbs:
Here are some comparison images of the ESB and ROTJ perspex block channels and some 1mm and 2mm diameter GoW (Grain of Wheat) lamps:
The ESB channels looks closer to the 2mm diameter GoW lamps, while the ROTJ channels are in the range of the 1mm diameter lamp.
We know that the ESB perspex block has not the same shape as the one in the ROTJ rangefinder body (the original image was replaced with a better one):
The ESB style is (was) also present on the Supertrooper/Pre-Pro #1 helmet, while the ROTJ style is (was) present on the Pre-Pro #2, Pre-Pro #3 and Sandy helmets.
And another fact: did you knew that the perspex block was made from 2 pieces glued together? Well, then here's the proof:
Additional images of the 2 part perspex block:
Here is a bit of history about the 'wheat of grain' light bulbs (shorter version; for the full history go here ==> Comments on the "Grain of Wheat" Lamp):
And more info here ==> Dollhouse LIGHT BULBSIt was the writer's intention to write a short story about the "Grain of Wheat" lamp, which, at one time, was the smallest of manufactured incandescent lamps.
The writer's knowledge of the grain of wheat lamp comes, in part, from two technical articles which were coauthored by Dr. William E. Forsythe in 1931 and 1932. The characteristics of the lamps measured by Forsythe are:
diameter of cylindrical bulb = 2 mm (0.078 inch)
bulb length = 8.7 mm (0.342 inch)
filament temperature was 2100ēK (2115ēK maximum)
volts = 1.5
consumed 0.17 watt
operated from a single dry cell
weight = 0.06 gram
candlepower = 0.028
These characteristics are mentioned because the term "grain of wheat" today applies to lamps of various voltages and sizes; this can be determined by putting the term in the search engine Google. Since about 1908 "grain of wheat" lamps contain a tungsten filament. Prior to that the filament was made of carbon.
The earlier of the Forsythe articles is dated December 1931. The writer therefore attempted to determine just when the term "grain of wheat" was first used for a sub miniature incandescent lamp. Such a date was never found. However some information regarding the use of such lamps was revealed.
It should be mentioned that the grain of wheat lamp is still widely used today as an indicator light, in model railroading, in doll houses, backlighting, etc. In addition, it no longer can claim to be the smallest incandescent lamp. Today "Grain of Rice" lamps exist as well as micro lamps. A picture of the relative sizes of these lamps is shown above.
The idea is that whatever these light bulbs are called now (GoW - Grain of Wheat, GoR - Grain of Rice or micro lamps), our task is to determine the exact size (mainly the diameter) and the position of these light bulbs in the perspex channels. My interpretation is based only on images from the Gallery and because the nature of the perspex block to magnify (+ or -) or to distort the inner channels, my measurement are not set in stone. Some of the rangefinder templates (WOF - WizardOfFlight and SS - SingleSeat) has a 1.5mm diameter for the perspex channels (somewhere between my 1mm and 2mm light bulb sizes) but these measurements might be off too because of the inner distortion seen in the images.
Here are some images with the working (or possibly working) Rangefinder red LED lights:
And another image with the perspex side view (more or less):
For the ESB light I can't take credit, because it was already noticed by Tyler Durden and Art (read more here ==> ESB Rangefinder inner light)
This update is mainly for images posted further down in this thread and its purpose is to keep all the images and the info in the first post too.
I made this file for fun and is partially perfect for this thread because of the blinking LED sequence in the rangefinder, it also has the chest light sequence presented in this thread ==> ESB Chest Display Sequence:
The rangefinder sequence is 0.5 second for each LED while the chest light sequence was slightly altered to fit in the LEDs sequence (the full sequence is presented in the ESB Chest Display Sequence thread). Also note that your browser might not run looped the GIF file, but if you save it and then open it with an image viewing program, the animation will loop again.