Letters from Readers

Market is bigger than represented
Your review of the diode-laser market ("Laser Marketplace 2002," February, p. 61) pays very little attention to the high-peak-power pulsed-diode market. Your comments are limited to a sentence about the weapons simulation market. While the market for these lasers does not compare in volume or dollars with the optical-storage market, the volume does compare favorably to other markets, and extremely well in some cases.

High-peak-power lasers have many other applications besides weapons simulation. Among them are optical proximity fuses for a large variety of missiles, from ground-to-ground to air-to-air and all varieties in between, as well as naval missiles. Such optical fusing technology is used by the U.S. as well as many of our allied nations. For example, during the major production years of the Sidewinder missile, 1975 to 1990, Laser Diode supplied over 400,000 lasers for this one program alone.

Other commercial applications for high-peak-power lasers include sensing for industrial robotics, surveying instruments, and civilian and military range-finding applications, which cover the gamut, from relatively simple laser-based golf rangefinders to highly sophisticated ceilometers that measure cloud height above airports in excess of 12,000 ft. Because of eye-safety concerns, a new generation of range finders will use 1550-nm pulsed lasers as the source. In addition, fiber pigtailed single-diode quasi-CW lasers may soon find increased usage for ordnance initiation in military programs—several programs are now close to production.

Stephen Lerner
Product Manager
High Power Components
Laser Diode Inc.
Div. Tyco Electronics Corp.
slerner@tycoelectronics.com

Reported dye concentration known for many years
In your article on a dendrimer dye lasers ("High-gain media leads to potent dendrimer laser," February, (p. 37),¹ it is stated that, "Conventional organic laser dyes produce large fluorescence yield, but typically are limited to low dye concentrations of less than 1 mM/l to achieve efficient spontaneous emission." The article goes on to report that the dendrimer dye laser was demonstrated at dye concentrations in the 1- to 9-mM/l range. In this regard, it should be noted that dye concentrations of several mM/l have been known in the field of laser-pumped dye lasers for a long time.² Further, an excimer-laser-pumped coumarin 153-tetramethyl dye laser was optimized for maximum output power at a concentration of 10 mM/l while yielding a conversion efficiency of 18.9%.

Finally, it is appropriate to mention that the article in World News provided a fair representation of the information conveyed in the original article that appeared in Applied Physics Letters.

Frank Duarte
Senior Research Physicist
Rochester, NY
fjduarte@opticsjournal.com

REFERENCES
1. S. Yokoyama, A. Otomo, and S. Mashiko, Appl. Phys. Lett. 80, 7 (2002).
2. C. H. Chen, J. L. Fox, F. J. Duarte, and J. J. Ehrlich, Appl. Opt. 27, 443 (1988).

CORRECTION
The photo of the laser guide-star system at the Keck II telescope (April, p. 30) should have been credited to A. Contos, W. M. Keck Observatory.