Rolf Illsley, who founded the first high-tech company in Sonoma County and led it for four decades as Optical Coating Laboratory Inc., and made scientific breakthroughs used around the world and in outer space, died this week. He was 95.

His company, known widely as OCLI, would become one of the largest private employers in Sonoma County before Illsley retired in 1991.

Illsley died Wednesday in Terra Linda, where he lived. The cause appeared to be heart failure. He was remembered Thursday as an irrepressible soul willing to take big risks and to approach any challenge with intensive inquiry.

“He was miles ahead of you and he was just totally devoted,” recalled Joe Apfel, the company’s former director of research.

Illsley’s son, Roger Illsley of Santa Rosa, said his father combined a great intellectual curiosity and a “can-do spirit.” Illsley lived “a classic 20th century American life,” his son said.

Rolf Illsley grew up in the Great Depression, served in the U.S. Navy in World War II and did United Nations relief work in China before joining with three partners to form an optical coating company in 1948. The partners soon left the company but Illsley persevered.

OCLI would pave the way for a new generation of technology companies in Sonoma County, making it easier for other high-tech companies to locate nearby because it had established a culture of smart, skilled employees critical to success. In 1999, The Press Democrat named Illsley one of the 50 people who had made the biggest impact on Sonoma County during the preceding century.

Before Sonoma County became a hub for Hewlett-Packard facilities or Telecom Valley manufacturers, there was OCLI.

It began operations here in 1950 and went on to make thin-film coated materials used in space exploration, consumer products and currencies printed around the world.

Its coatings were used on the windows of the Mercury spacecraft that John Glenn peered through in 1962 as he orbited the Earth. In the 1970s, the company made special mirrors for the Polaroid SX-70 instant cameras, considered one of the most innovative consumer products of its time.

Today, the coloring shift ink that the U.S. government places on certain currency notes to prevent counterfeiting stems from discoveries made at OCLI. That ink, used by more than 100 countries, now is produced by the Santa Rosa division of Milpitas-based Viavi Solutions. Viavi is an offshoot of JDSU, which purchased OCLI in 2000 for $6.2 billion, the second-largest corporate takeover in Sonoma County history.

Santa Rosa became home to OCLI thanks in part to the advice of an Oakland motorcycle shop owner. Illsley, then 30, had traveled east from Washington, D.C., on his Velocette motorcycle in search of a new home for his young company.

In a interview last May with Press Democrat columnist Gaye LeBaron, Illsley recalled how the shop owner had suggested Santa Rosa.

Illsley visited the town and within two days decided it was a good place to put down roots.

He developed a set of core values that he believes made OCLI successful: Treat people fairly, with respect and dignity; have the best technology; hire the best people; give them the encouragement and the advanced equipment they need to experiment and to excel; and “if your conviction is strong enough, accept the risk in order to achieve.”

From a small laboratory on Sebastopol Road, Illsley gathered physicists, chemists, engineers and finance officers from the East Coast and Germany and Southern California to the rural community he had adopted. Key employees joined Optical Coating in the early days and never left the company.

“There’s a brightness, a sparkle about him, that is motivational. People enjoy the ideas, the challenges and the successes,” John McCullough, OCLI’s chief financial officer for many years, said in a 1999 interview.

Among the big bets Illsley made was to develop in 1970 a 100-foot processing line that made high-performance mirrors and anti-reflective glass by passing materials through a series of dust-free vacuum chambers.

The line greatly increased production capability, compared to using a single chamber where workers could apply only one coating at a time to the glass.

The processing line cost $2 million to build, Illsley recalled in a 2014 interview. At the time that was roughly equal to the net worth of OCLI.

“If it had failed,” he said, “there is a chance that the company would have failed.” Instead, the line proved a success and Illsley estimated its output over more than four decades probably could cover an area of 2 square miles.

Illsley was born in Ohio and grew up in Michigan. He graduated in agricultural economics from Michigan State University and served as an engineering officer on an amphibious ship in the Philippines in World War II.

In the late 1990s, Illsley in retirement found a similar amphibious ship that had been passed down to the Greek Navy. He worked to get Greece to provide the vessel and had a Russian tug bring it across the Atlantic and dock in the Midwest on the Mississippi River, his son said. The ship eventually had to be scuttled, but not before Illsley arranged a reunion of veterans who had served on such ships.

When he was 30, Illsley made a list of what was really important to him. The 11 items began with: “Have a feeling, when I’m 80, of a life well spent.”

Illsley told Men’s Health magazine in 2013 that “today, at 91, I’m proud to say I’ve achieved everything on that list.”

Along with his son, Roger, Illsley is survived by three other children, Lisa Navarro, Mark Illsley and Linda Illsley, all of Santa Rosa; and his wife of roughly a quarter-century, Helen Illsley of Terra Linda.

Other survivors include 10 grandchildren and three great-grandchildren.

Services are pending.