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A Vintage HeNe Laser Power Supply

It’s fun to build simple circuits in order to use surplus gear. Here is one example from Popular Electronics, September 1991.[1] There is an array of newer designs using more modern components, but all of the parts below are still available.

“Configured as an astable multivibrator, the 555 oscillates at approximately 500 Hz. The output of U1 at pin 3 is fed to the base of Q1, causing it to alternate off and on in time with U1’s output. The collector of Q1 is connected to the base of Q2. As Q2 turns on and off, a rising and collapsing magnetic field is created in the primary winding of L1 (the auto ignition coil). The rapid switching of Q2 induces a sufficiently high voltage in the secondary of L1 to drive the laser tube.”

Counterfeit 2N3055 transistors are inferior and common on eBay and Amazon. They should be purchased at one of the major distributors (e.g. Mouser, DigiKey).

See the reference below, for full details.

Reference: Gregory Gray, “Build a simple laser power supply,” Popular Electronics p. 32, September 1991. Today, this link works: https://worldradiohistory.com/Archive-Poptronics/90s/91/PE-1991-09.pdf

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Crisis: No Optical Glass

“Before the war (World War I), the optical industry in this country (USA) was in the hands of a few firms. Several of these were under German influence and one firm was directly affiliated with the largest manufacturer of optical instruments in Germany; the workmen were largely Germans or of German origin; the kinds and design of apparatus produced were for the most part essentially European in character; optical glass was procured entirely from abroad and chiefly from Germany. Educational and research institutions obtained a large part of their equipment from Germany and offered no special inducement for American manufacturers to provide such apparatus. Duty-free importation favored and encouraged this dependence on Germany for scientific apparatus.

With our declaration of war, the European sources of supply for optical glass and for optical instruments were cut off abruptly. Even before our entry into the war and especially after hostilities began in 1914, manufacturers of optical instruments realized that the European supply of optical glass might be stopped and they began experiments on its manufacture….The quality of glass obtained was not, however, entirely satisfactory…..Such was the situation in April 1917.”

Global supply chains are beneficial and can be problematic.

Bausch & Lomb Optical Co. of Rochester NY received a visit on April 4, 1917 from the US War Department. B&L’s Mr. Victor Martin, a Belgian glassmaker, is credited with helping to start the B&L glass manufacturing plant in 1912. The government’s goal in working with B&L was to introduce discipline into the manufacturing process quickly. By November 1917, the B&L processes had been mastered and placed into production. These processes were shared with other manufacturers immediately to help build war-time capacity.

During April 1917, the total production of usable optical glass in the US was only 2,850 lbs. By September, monthly production was 10,775 lbs. December production was 42,451 lbs. For the full year 1918, 529,853 lbs of usable optical glass were produced in the US. The glass consisted of ordinary crown, borosilicate crown, barium crown, dense barium crown, light flint, and dense flint. Just six types.

The optical glass manufacturing industry went from low quality and dependency to near self sufficiency in 18 months. Serious disagreements can be motivating.

Reference: Ordnance Department, Document No. 2037, “The manufacture of optical glass and of optical systems: A war-time problem,” May 1921.

Featured Image: Workers at Bausch & Lomb, c. 1917, building up clay pots used for glass melting. Improving the design and composition of the pots proved an important factor in eliminating imperfections from optical glass. [Courtesy of Geophysical Laboratory Archives, Carnegie Institution of Washington]