The term “home-made laser” almost seems a contradiction but that is not the case. This gas laser was built by high school student Stephen M. Fry in 1964, only four years after Ali Javan made the first gas laser at Bell Labs. Fry followed plans published in Scientific American's "The Amateur Scientist" column in September 1964, (page 227).
The glass tube is filled with helium and neon and, as the magazine reported, "seems to consist merely of a gas-discharge tube that looks much like the letter 'I' in a neon sign; at the ends of the tube are flat windows that face a pair of small mirrors. Yet when power is applied, the device emits as many as six separate beams of intense light."
The discharge tube is the only piece of this particular laser that remains. The flat windows (called "Brewster windows") are square instead of round, and the electrodes are parallel to the gas tube instead of perpendicular. Otherwise it resembles the drawings in the magazine. Fry later earned a Ph.D. in physics with a dissertation on lasers.
Dolby model A301 audio noise reduction unit, serial no. 2. Unit uses Dolby A-type noise reduction circuitry and was produced for professional recording studios and cinema sound production studios. This unit was used by Decca Records.
Hourglass style timer for long-distance telephone calls. A clear plastic block containing a small 3-minute hourglass with orange sand, and a rotary-type desk telephone medallion. Used to time telephone calls in an era when making long-distance calls was quite expensive. Markings: Partial sticker on reverse: “Ma[de in] Hong [Kong]”. Remaining label text matches that of a similar unit seen online.
Fedtro model CH-AHD battery charger on package. This unit purports to charge batteries of all types, but ordinary carbon batteries are not rechargeable and attempting to recharge them creates a significant safety hazard. The UL citation refers only to the cord and connector plug, a typical two-lead 18 gauge cord, not the entire unit. The patent referred to (258299) may refer to a Japanese patent. US 258299 is an unrelated 1882 patent for a pen point; and US D258299 is a 1978 design patent for a toy chain saw.
Eveready “Captain” flashlight in original package. Unit used 2 C-cell batteries and a PR4 or PR2 miniature lamp. Markings: Stamped on bottom: “Made in U.S.A. / Eveready / Trade Mark / [Union Carbide logo]”; label on front: “Eveready / Captain”. Package printed on one end: “Eveready / 2 ‘C’ cell / Captain / Flashlight / No. 9231”.
This helium-neon laser tube was used along with a crystal (catalog #2022.0154.01) for mode-locking experiments at Bell Telephone Labs by Logan E. Hargrove in 1963. The tube helped Hargrove and colleagues demonstrate the phenomenon of mode-locking with laser emissions. The technique of mode locking allows for generation of extremely short pulses of laser light. Such lasers are valuable for laboratory research investigating physics, chemistry, and optical phenomena that occur on very short timescales, as well as having medical applications.
Written on tipped end: “ML22”. Metal tag removed from tube etched: “7052 glass ML22 Avg I.D. = .213” ”. Paper tag removed from tube written: “Tube ML22 (concentric) 40[m?]a Box #12 30K[ohms] [??1]92 KV 4.4 [amp?] filament.”
References: US Patent #3412251, “Mode Locking in a Synchronously Modulated Maser,” filed 24 April 1964, issued 19 November 1968 to Logan E. Hargrove, assigned to Bell Telephone Laboratories. See also: Valdmanis, J. A., Richard L. Fork, and James P. Gordon, “Generation of optical pulses as short as 27 femtoseconds directly from a laser balancing self-phase modulation, group-velocity dispersion, saturable absorption, and saturable gain,” Optics Letters 10, no. 3 (1985): 131-133.
This is an experimental ruby laser made in 1963 at Ohio State University. Edward Damon, a researcher at the University’s Antenna Laboratory, made this and several other lasers during his investigation of Theodore Maiman’s ruby laser experiments of three years earlier.
In addition to replicating Maiman's 1960 experiments, Damon wished to explore variations of the ruby laser. Unlike Maiman's laser, this laser does not use a spiral flashlamp to energize the ruby crystal. Instead, Damon placed three linear flashlamps parallel to the rod-shaped laser crystal. Firing these lamps simultaneously provided energy to the crystal. The laser also demonstrates a water cooling technique still used in some lasers today.
This small, portable wire recorder is an interesting example of transistorized miniaturization. The user can carry the recorder in a coat pocket while wearing the wrist-watch microphone with a connecting wire running up the sleeve. The watch does not keep time but serves solely as an unobtrusive microphone. The recorder does not use transistors but rather uses vacuum tubes. It thus requires three batteries: one for the motor drive, one for the tube filaments and one for the tube anodes.
Accessories include the wristwatch microphone, a power supply, an automobile adapter, a headset, and three patch cords. It is unclear how much noise the motor assembly made and so how useful this recorder may have been in making secret recordings. Since the tubes would have generated heat it’s also probable that the device might have been uncomfortably warm if worn. The donor’s father owned a business equipment store in Washington, D.C., and may have acquired this piece through the store. A handwritten evaluation was critical and did not recommend acquiring the product.
Nippon Electric Company (NEC) produced this reel-to-reel tape recorder around 1962. Japanese industry took advantage of the post-World War II rebuilding effort to modernize their factories and enter markets for high-technology devices. Many of these devices used transistors in place of older vacuum tube technology. Modern, efficient factories and low labor costs made Japanese products price competitive with American products. This recorder has an inexpensive plastic case and operates with seven transistors.