Lens Testers for Transmission, UV and Stress
Measure UV, blue-light and visible transmittance, demonstrate photochromic darkening, or inspect mounting stress. A transmission meter, a demonstrator and a polariscope serve three distinct lens checks.
A transmittance meter, a demonstrator and a polariscope, each for a different job at the counter.
Three instruments for distinct lens checks
CP-18B
Transmittance at 400, 430, 465 nm and visible.- Measures
- Transmittance
- Wavelengths
- 400 / 430 / 465 nm, visible
- Resolution
- 1%
- Screen
- 4.0" color LCD
CP-18C
UV and photochromic lens tester for the counter.- Shows
- UV and photochromic
- Power
- 10 W
- Weight
- 0.9 kg
- Size
- 236 × 157 × 57 mm
LY-15
View mounting stress patterns in spectacle lenses with two polarising rings and a push-button illuminator.- Inspection
- Visible stress patterns
- Principle
- Polarised light
- Power
- 15 W
- Listed weight
- 336 g
Which tester do you need?
Compare the CP-18B transmission meter and CP-18C demonstrator below. The LY-15 adds a separate visual check for mounting stress; it does not measure transmittance.
| CP-18B | CP-18C | |
|---|---|---|
| What it gives you | Transmittance readings in % | A visual demonstration |
| UV | Reading at 400 nm | UV blocking comparison |
| Blue light | Readings at 430 nm and 465 nm | |
| Visible light | 380–760 nm | |
| Photochromic | Indicative only | Darkening under UV |
| Power | DC 5 V / 2 A, optional battery | AC 220 V / 110 V, 10 W |
Presenting lens performance honestly
UV400
Sources define UV400 differently, at 400 nm, 395 nm or 380 nm, and sunglass standards set their own limits. Quote the wavelength with the reading: “0% transmittance at 400 nm” is a claim you can defend.
Photochromic lenses
Darkening depends on UV, temperature and lens material. Car windshields block most UV, so most photochromics darken only slightly in the car. Tell customers before they find out.
Blue light
Describe transmission, not health. A 2023 Cochrane review found blue-light filtering spectacles probably make no short-term difference to eye strain, and the UK College of Optometrists advises against promising less fatigue, better sleep or macular protection.
Simple torches and pens
A blue-light pen or UV torch shows a visible difference at its own wavelength. It does not measure how much light is blocked.
Background sources: Demonstrating lenses (20/20 Magazine) · Blue-light filtering spectacles, Cochrane review 2023 · College of Optometrists on blue-light filtering lenses (2023)
Lens tester questions
Does a UV test prove a lens is UV400?
A demonstration shows that some UV is blocked. A meter such as the CP-18B gives a value at 400 nm; quote the wavelength with it.
Can I tell customers blue-light lenses protect their eyes?
We advise against it. Show transmission figures and let the customer decide.
Why do photochromic lenses not darken in the car?
The windshield blocks most of the UV that activates them.
Do I need both the CP-18B and CP-18C?
Not necessarily. If you want numbers, start with the CP-18B; if you mainly sell photochromics, the CP-18C shows the effect best.