Segment Reporting - Assets for Each Reportable Segment (Detail) - USD ($) $ in Thousands	Mar. 28, 2020	Dec. 28, 2019
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated total assets	$ 123,379	$ 126,322
Cash and investments	42,440	42,024
Restricted cash	787	787
Deferred income taxes	6,138	6,252
Other current assets	1,195	752
Common property, plant and equipment	1,531	1,307
Common operating lease right-of-use assets	1,794	1,898
Other assets	0	78
Operating Segments
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated total assets	69,494	73,244
Operating Segments \| TFE
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated total assets	46,007	51,153
Operating Segments \| Photonics
Segment Reporting, Asset Reconciling Item [Line Items]
Consolidated total assets	$ 23,487	$ 22,071

Common operating lease, right of use assets.

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, without jurisdictional netting.

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Amount of cash and cash equivalents restricted as to withdrawal or usage, classified as noncurrent. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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