Zeiss Winkel GFL

Repair and LED Conversion

By Dushan Grujich, on June 10^th. 2014

Zeiss Winkel GFL 654-632

Microscope came equipped with a set of phase contrast objectives, a pair of 12.5X oculars, with intermediary image distance 5.0 mm designed for optical TL of 155.0 mm - mechanical TL - 160 mm, and immersion PC condenser with capability of bright field and dark field observation. All parts present but the lamp holder for the illuminator, which fits into the 'scope base. Detailed description of all the options are given in the user's manual¹. It is interesting to note that objectives do not have any traces of delamination, that is otherwise quite common for Zeiss optics of the period.

The set of four objectives supplied with microscope, RMS thread 45 mm parfocal distance (pre DIN), consists of:

2.5X 160/0.08	Plan achromat	P/N 44 01 10	Brown band
10/0.25 160/	Ph1 achromat	P/N 46 04 01	Yellow band
40/0.65 160/0.17	Ph2 achromat	P/N 46 07 01 or 46 17 03	Light blue band
100/1.30 160/-	Ph3 Neofluar Oel	P/N 46 19 21	White band

Zeiss Winkel GFL base with place for the lamp holder, the three collector lenses are housed within the mirror assembly.

Image also shows one part missing, which should have been held by two M2 screws, one of which was broken off with threaded part embedded into the aluminium base. It was necessary to be drilled through and re-threaded, tough job as the base is die cast aluminium and screw is steel.

The part missing was a small indexing plate which serves to index the mirror assembly correctly as well as to allow adjusting of field aperture diaphragm. Thus I made a replacement, from a 1 mm thick brass plate, I drilled through the remnant of the screw and re-tapped the hole to accept new M2 screw to hold replacement index plate, as seen on the image above.

Image above shows part of the index plate protruding up to index the mirror assembly

The original, missing, lamp holder with an incandescent 15W 6V lamp

Assembled "lamp" body machined out of dur-aluminium round stock, with a LED in front and DC power receptacle on the rear

Having decided not to pursue acquisition of the original lamp holder I have machined replacement which fits inside the base. I have made sure that the LED crystal is in exact plane where the tungsten filament would be. Since use of the power LED does not require frequent "lamp" replacements I have placed DC power receptacle on the rear side of the LED holder and to prevent it from accidentally coming out or from changing the postion of the LED I have drilled and tapped a hole for an M3 hex socket grub screw.