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Applying Thermal Compound to Large Aperture Fusion Pro Optics

Introduction

On the large aperture Fusion Pro systems, the optics are designed with a thermal compound applied between the mirror and its holder. Replacement mirrors include this compound pre-applied to the backside of the mirror. For routine cleaning and maintenance, additional thermal compound is not required-the existing layer remains sufficient for effective heat transfer from the mirror to the heat sink (mirror holder). However, if reapplication is necessary, follow the procedure below to ensure proper installation.

Applying Thermal Compound

  1. Ensure both the mirror and the holder are clean and free of dust or debris.

    Clean mirror

    Mirror

    Clean mirror holder

    Mirror Holder

  2. Apply a small dab (approximately 0.2″ or 5 mm) of thermal compound to the center of the mirror’s backside.

    Thermal compound applied to mirror

  3. Press the mirror firmly onto the holder and gently rotate it to spread the compound evenly between the surfaces.

    Pressing and rotating the mirror onto the holder

  4. Ensure no excess compound is visible around the edge of the mirror. Only a thin internal layer should remain.

    No thermal compound visible at the edge

  5. The goal is a very thin, well-distributed layer of thermal compound that stays within the bonded area and does not reach the outer edge of the mirror.

    Proper thin layer of compound without spillover

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  • ID:
    KA-01692
  • Date:
    07/11/2025

Parts & Resources:

  • LC1369 Thermal Compound

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