Red Laser Pointer Research Articles

An aqueous photopolymer for classroom holography

An aqueous photopolymer possessing good photosensitivity for recording holograms in red laser light is described. This development follows the author’s earlier discovery of the enhancing effects of an acid-base amine combination used as a free-radical producing co-initiator with methylene blue dye to polymerise suitable monomers. The system also works with green laser light using the dye safranine-O. After exposure, the image develops in water. With this photopolymer, individual students in a classroom can use small cheap red laser pointers with their collimating lenses cut off to make simple Denisyuk holograms under subdued lighting. As the polymer is water-based, its preparation in a school lab is feasible.

Need a single-mode red laser, cheap? Check your pockets!

An inexpensive (<$5) key-chain model of red laser pointer (RLP) operates with typically 98% of its total emission in a single longitudinal cavity mode. The laser self-tunes with time, interpreted as due to thermal effects. The laser can also be tuned by varying its operating current and voltage. These properties permit one to quickly and easily record absorption spectral segments spanning ranges of 1–6cm−1, with high quantitative reliability, resolution, and accuracy. As examples, spectra of I2 are recorded in the 650nm region as a function of pressure for several RLP wavelengths and are used to estimate the strength of the underlying continuum (due to A←X absorption) with relative standard error less than 1%. Similarly, measurements of the integrated line absorption on selected lines in the B←X transition yield estimates of the electronic transition strength with unprecedented precision.

The power output of laser pointers: do they exceed federal standards?

Concern about the safety of laser pointers has increased as these devices have become readily available to the public, which includes children who may use them improperly. According to federal (Food and Drug Administration) standards, laser pointers are class 3a devices, and power output cannot exceed 5.0 mW. We tested a sample consisting of 29 red diode laser pointers obtained from various sources that were equipped with fresh batteries. Power output was measured with an optical power meter with the sensor 5.0 cm from the laser. The laser was turned on for 60 s and a reading was taken every 10 s. This procedure was repeated five times for every laser. The power output of unaltered lasers ranged from 0.7 mW to a high of 3.9 mW. Alterations to some of the lasers increased the output slightly above 5.0 mW. When the laser pointers in our sample were used as packaged, they did not exceed the federal standards of 5.0 mW.

Selected for Presentation

The abstract submitted by Dr Q has been selected by the Program Committee for presentation at the annual meeting of the American Society of Medicine. The physician gives his secretary the material to be put on the slides. The secretary instructs the artist or photographer to prepare them by certain date in the near future. The doctor reviews the slides with a hand magnifier, often adorns them with his fingerprints and arranges them in sequence. The speaker arrives promptly for his lecture and gives the slides to the projectionist. The chairman introduces Dr Q; quickly explains the function of various buttons; how to use the new red laser pointer; and hangs the microphone around his neck. The speaker is warned about the two-minute yellow light and the blinking red light on the podium. The physicians and the audience are eager and attentive. The lights are bright and quietude prevails. The