The Company has one operating segment, which is the sale, design, manufacture, marketing and support of optical critical dimension and thin film systems. The following tables summarize total net revenues and long-lived assets (excluding intangible assets) attributed to significant countries (in thousands):

	Three Months Ended				Nine Months Ended
	September 28, 2019		September 29, 2018		September 28, 2019		September 29, 2018
Total net revenues:
United States	$	14,091	$	8,414	$	40,135	$	22,545
China		20,357		14,486		60,590		50,861
Japan		11,189		19,693		19,720		48,090
South Korea		10,519		23,598		37,557		92,397
Taiwan		8,590		1,883		23,529		4,918
Singapore		2,775		5,842		13,049		20,377
Other		5,604		2,674		13,265		8,319
Total net revenues	$	73,125	$	76,590	$	207,845	$	247,507

	September 28, 2019		December 29, 2018
Long-lived tangible assets:
United States	$	51,152	$	46,325
International		1,297		1,575
Total long-lived tangible assets	$	52,449	$	47,900

With respect to customer concentration, SK hynix, Intel Corporation, Toshiba Memory Corporation, Taiwan Semiconductor Manufacturing Company, and Samsung Electronics Co. Ltd. each accounted for more than 10% of total sales for the three months ended September 28, 2019, and SK hynix, Intel Corporation, Taiwan Semiconductor Manufacturing Company Limited, and Samsung Electronics Co. Ltd. each accounted for more than 10% of total sales for the nine months ended September 28, 2019. Samsung Electronics Co. Ltd., Yangtze Memory Technologies Co. Ltd., SK hynix, and Toshiba Memory Corporation each accounted for more than 10% of total sales for the three months ended September 29, 2018 and Samsung Electronics Co. Ltd., SK hynix, Toshiba Memory Corporation, Yangtze Memory Technologies Co. Ltd., and Micron Technology, Inc. each accounted for more than 10% of total sales for the nine months ended September 29, 2018.

With respect to accounts receivable concentration, Yangtze Memory Technologies Co. Ltd., Toshiba Memory Corporation, and Taiwan Semiconductor Manufacturing Company each accounted for more than 10% of total accounts receivable as of September 28, 2019. SK hynix and Toshiba Memory Corporation each accounted for more than 10% of total accounts receivable as of December 29, 2018.