Customer inspection and testing of optical components for their conformity to stated requirements (either after manufacturing by source inspection or at incoming inspection after receiving them from the suppliers) are critical for their functionality in the next and final steps.
There are three main categories of items (or assemblies) that are purchased by organizations:

• Build to print (BTP), which refers to a situation that requires the contractor (producer) to build a product according to the exact technical specifications given by a customer.
• Build to specification/spec (BTS), which refers to a situation where the product is built according to the contractor’s (producer’s) technical specifications and after customer approval.
• A shelf (or off-the-shelf) item, which has been developed and produced to military or commercial standards and specifications, is readily available for delivery from an industrial source and may be procured without change to satisfy the purchaser. These kinds of items are sometimes put on the shelf in storage for potential customers before an order is received; they are published by the producer in his technical catalogs.

These categories are important because they affect the kind and size of inspection/test that is performed. The inspection and testing of optical elements, as detailed in this chapter, is connected directly to all functions involved in receiving good components:

• The designer who is responsible for the design and determining the technical requirements in drawing and specifications;
• The purchasing department that is responsible for finding the right supplier/manufacturer;
• The supplier/manufacturer that is responsible for supplying or manufacturing the components exactly as stated in the drawings and specifications, and verifying their conformity, and
• The customer’s inspector who is responsible for reviewing and assessing the conformity to requirements of the purchased elements.

IMPORTANT NOTE:
The purchase order should include a clear requirement for the reports that the customer wants to receive along with the purchased elements. If this is done, the producer will prepare these documents and deliver them along with the supplied elements as a part of the purchasing order. Customers who do not ask for the needed reports might not get them!