No, they are not the same.
Today, we have a variety of light meter manufacturers making photometric and radiometric meters. All of these light meters provide a measurement number or several measurement data points. However, how accurate and repeatable are those measurements, especially over time? The major question any user of either a photometric and radiometric meter needs to ask, does my application require precise and accurate measurements (mw/cm2, mj/cm2, w/cm2, or j/cm2) or just relative measurements?
For those UV application requiring accurate and repeatable measurements:
G&R Labs’ UV light meters are designed and manufactured for those applications requiring accuracy, repeatability, interchangeable probes measuring different wavelengths, and are all traceable to NIST standards within +/-3% published specification. We have an in house +/-0.5% Radiometric standard and a +/-1% Photometric standard and all tied to a known NIST wavelength standards. It takes extra work in design, making sure we have stringent quality control, our calibrations are based on NIST standards, and we know the value of accuracy in meeting your application needs.
Also, all of our UV light meter are issued with a calibration certificate whether it is a new meter or a recalibrated meter.
For those UV applications requiring perhaps a relative measurement, consider these points:
- A key factor in purchasing a uv light meter could be the ability to interchange probes to measure different wavelengths. Meters without interchangeability have problems with accuracy and repeatability from meter to meter since the meter and the probe is tested as a complete unit. A problem can occur if you were to purchase two meters from the same manufacturer at different times. This disparity occurs because of electronic circuitry variations, glass filters (consistency of thickness and material) and within the uv meter probe design.
- If the meter is not traceable to NIST standards when you send it for recalibration or because the meter needs repair you must have the original reference point to match it against when it was first setup. The safest place to be is to have this reference point based upon the NIST Standard since you will always be able to get back to the original traceable value.
- A wide range of glass filters are available. Some of these filters will degrade over time and care must be taken in selecting quality glass filters which are more costly but do not degrade over time.
- As a mercury arc lamp ages, a deterioration occurs resulting in loss of intensity (mw/cm2). This degradation is evidenced by the black film that builds up on the glass envelope of the lamp which filters out UV wavelengths. This loss can and normally does impacts your measurement results. Only by accurately measuring this degradation can you know when to replace your mercury arc lamp.
- A number of these low cost UV meters are simply disposables. It cost more to try an recalibrate the meter than purchase a new one.
Thank you for contact us and we look forward to meeting your application needs.