4. Goodwill and Intangible Assets

The changes in the carrying value of goodwill for the three month period ended September 30, 2018 are as follows (in thousands):


					Optoelectronics
					and
	Security		Healthcare		Manufacturing
	Division		Division		Division		Consolidated
Balance as of June 30, 2018	$	191,810	$	40,157	$	60,246	$	292,213
Goodwill acquired or adjusted during the period		4,811		—		7,415		12,226
Foreign currency translation adjustment		(11)		7		282		278
Balance as of September 30, 2018	$	196,610	$	40,164	$	67,943	$	304,717

Intangible assets consisted of the following (in thousands):


		June 30, 2018						September 30, 2018
	Weighted	Gross						Gross
	Average	Carrying		Accumulated		Intangibles		Carrying		Accumulated		Intangibles
	Lives	Value		Amortization		Net		Value		Amortization		Net
Amortizable assets:
Software development costs	9 years	$	28,174	$	(9,423)	$	18,751	$	28,621	$	(10,159)	$	18,462
Patents	19 years		8,401		(1,618)		6,783		7,866		(1,580)		6,286
Developed technology	10 years		52,780		(9,706)		43,074		54,650		(11,091)		43,559
Customer relationships/backlog	7 years		63,398		(17,891)		45,507		68,840		(20,723)		48,117
IPR&D	5 years		2,290		—		2,290		2,290		—		2,290
Total amortizable assets			155,043		(38,638)		116,405		162,267		(43,553)		118,714
Non-amortizable assets:
Trademarks and trade names			25,596		—		25,596		26,516		—		26,516
Total intangible assets		$	180,639	$	(38,638)	$	142,001	$	188,783	$	(43,553)	$	145,230

Amortization expense related to intangible assets was $4.2 million and $5.3 million for the three months ended September 30, 2017 and 2018, respectively. At September 30, 2018, the estimated future amortization expense was as follows (in thousands):


2019 (remaining 9 months)	$	15,454
2020		19,628
2021		19,111
2022		14,702
2023		13,559
Thereafter, including assets that have not yet begun to be amortized		36,260
Total	$	118,714

Software development costs for software products incurred before establishing technological feasibility are charged to operations. Software development costs incurred after establishing technological feasibility are capitalized on a product by product basis until the product is available for general release to customers at which time amortization begins. Annual amortization, charged to cost of goods sold, is the amount computed using the ratio that current revenues for a product bear to the total current and anticipated future revenues for that product. In the event that future revenues are not estimable, such costs are amortized on a straight line basis over the remaining estimated economic life of the product. Amortizable assets that have not yet begun to be amortized are included in Thereafter in the table above. For the three months ended September 30, 2017 and 2018, we capitalized software development costs in the amount of $0.1 million and $0.4 million, respectively.