Re: Optical properties of castable clear materials

From: Olinda Rush (
Date: Mon Aug 02 1999 - 18:16:06 EEST

SG 95, available from MCP Systems, is an optically clear polyurethane resin. Many service bureaus and OEM are currently casting lens type prototypes with this resin. The Optical properties are as follows
Refractive Index - 1.51; Transmissivity - 88.1%; Diffused Lights - 0.9%; Paralleled Lights - 87.2%.
This resin does not contain a UV stabilizer so these properties will change over time. It is designed to be cast in an automated MCP VaCast chamber for a virtually void free clear part. This material is available worldwide through the MCP Group.

Olinda W.Rush
MCP Systems
Senior Sales Representative
phone: 973.267.0549
fax: 973.267.1138
    -----Original Message-----
    From: Dev Thevalingam <>
    To: <>
    Date: Sunday, August 01, 1999 8:56 PM
    Subject: Optical properties of castable clear materials
    I intend to cast clear prototypes in epoxy or PU out of silicone mold. Original part designed for injection molding in Acrylic has multiple faces of light refraction and internal reflection. It has a narrow operational window of optical design and expect the design is sensitive to optical properties, mainly to refractive index. I could not find optical properties of clear castable epoxy or PU.
    Anyone out there has golden experience of making multiple prototypes of lenses or similar optical items??? At least source of optical properties for castable clear materials would be useful to me.
    Thanks in advance.
    Dev K Thevalingam
    Mechanical Engineer - Research
    Australian Arrow Pty Ltd
    65 Lathams Road, Carrum Downs, Australia 3201
    Tel.: + 61 3 9785 0835

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