HSE/NLP test slide (Mark II) is the tradename of a product supplied by PTR OPTICS, Unit D9, Cross Green Approach, Cross Green Industrial Estate, Leeds, Yorkshire, LS OSG, England
The microscope shall be set up according to the manufacturer's instructions, and the detection limit checked using a 'phase-contrast test slide'. Up to code 5 on the AIA test slides or up to block 5 on the HSE/NPL mark 2 test slide must be visible when used in the way specified by the manufacturer. This procedure shall be carried out at the beginning of the day of use.
The Phase Contrast Test Slide was developed by the Health and Safety Laboratory (HSL) on behalf of the Health and Safety Executive (HSE) in collaboration with Optometrics (UK) Ltd. and the National Physical Laboratory (NPL). (The slide was previously known as the HSE/NPL test slide). Its purpose is to provide a reproducible phase object to check microscope performance prior to counting asbestos fiber samples.
