Photochromic Lens Testing

The Bentham BPC300 is a turn-key solution for the characterisation of photochromic lens transmission in accordance with international standards and a key tool in the development of photochromic formulations.

The fully automated system yields transmission data for uncut finished lenses, in accordance with the EU Medical Devices Directive 93/42/EEC (implementing EN ISO 8980-3:2013) and for sunglasses in accordance with the EU Personal Protective Equipment directive, 89/686/EEC (implementing EN ISO 12312-1:2013).

Key features include:

• Measurement of spectral transmission 280-780nm in faded and darkened states
• Optically chopped monochromatic probe
• AM2 conditioning beam (including facility to attenuate and filter spectrum)
• Temperature-controlled water bath
• Fully-automated by the BenWin+ proprietary Windows application
• Generation of measurement report including parameters required by standards



τV0 Luminous transmittance in the faded state at (25±2)°C
τV1 Luminous transmittance in the darkened state at (25±2)°C
τV0 /τV1 Photochromic Response
τVW Luminous transmittance at (5±2)°C
τVS Luminous transmittance at high temperature (5±2)°C
τVA Luminous transmittance at reduced solar simulator level and (25±2)°C
τSUVA Mean UVA spectral transmittance weighted by AM2
τSUVB Mean UVB spectral transmittance weighted by AM2
Qsign Visual attenuation coefficient for red, green, blue and yellow incandescent
τsb Solar blue light transmittance
Also reported are: Lens category
Colourimetric parameters: CIE 1931 & CIELab
The rate of darkening and fading may also monitored at a single wavelength

Table 2: Parameters reported by BPC300