Weather stations
Scientific and educational studies

Pollution monitoring

Environmental monitoring


High accuracy.

Highest grade filters are embedded into a solid cast aluminum housing which assures accurate, stable optical alignment. Low noise electronics and a 20 bit A/D converter allow high linearity, resolution and dynamic range.

Ease of use.

No computer knowledge is necessary to make measurements. Just aim the meter at the sun, align the image of the sun with the cross-hairs and push the button. In few seconds the measurement will be completed and the result stored in memory.


A small hand-held device is all you need to perform measurements. No additional computer is necessary.

Instantaneous results.

The Aerosol optical thickness calculation algorithms are programmed in the MICROTOPS II and the final results of all stored scans can be conveniently viewed on the LCD. The raw data is also stored to allow retrospective adjustments of algorithms.

Non-volatile memory.

The raw data collected by the MICROTOPS II, as well as calculated results are stored in non-volatile memory. Each data point is annotated with date, time, site coordinates, solar angle, altitude, pressure and temperature.

Low cost.

By implementing the latest technology, instrument cost has been brought well below that of comparable sunphotometers, without sacrificing accuracy or features.

Computer interface.

Connection to a PC through a USB interface enables transfer of collected data. MICROTOPS Organizer, a Windows-based software automates data retrieval and archiving.

Optical Channels:

305.5 ±0.3 nm, 2.0 nm FWHM
312.5 ±0.3 nm, 2.0 nm FWHM
320.0 ±0.3 nm, 2.0 nm FWHM
936 ±1.5 nm, 10 nm FWHM (optional)
1020 ±1.5 nm, 10 nm FWHM (optional)

Stray light:

1E-9 for 305.5 nm filter
1E-8 for 312.5 nm filter
1E-8 for 320.0 nm filter
1E-6 for 936 nm filter
1E-6 for 1020 nm filter


0.0001uW/cm² on 305nm channel

Dynamic range:


Viewing angle:




Non linearity:

max 0.002% FS

Operating environment:

0 to 50°C, no precipitation

Computer interface:


Power source:

4xAA Alkaline batteries


21 oz (600 grams)


4"W x 8"H x 1.7"D (10x20x4.3 cm)

Microtops® II calibrations are carried out using a Langley plot. NIST N/A. [Hold]
Model 521
Model 520

• MICROTOPS II® OZONOMETER MODEL 521 Meters_Model-521-.pdf


Microtops II Ozonometer Owners Manual (524K)

Find out how to submit your MICROTOPS II® ozone data to the World Ozone and Ultraviolet Radiation Data Centre
Total column ozone content and aerosol optical thickness measurements: Instrument performance analysis with respective TOC datasets available here - A. Aculinin, V. Smicov Institute of Applied Physics, Academy of Sciences of Moldova, May 30, 2006
Atmosphere Poster (363K) Presented at Quadrennial Ozone Symposium Charlottesville, Virginia, USA June 4-13 1992 Daniel Berger, Marian Morys
Ultraviolet radiation as applied to photoclimatherapy at the Dead Sea (114K) A.I. Kudish, PhD, D. Abels, MD, and M. Harari, MD - International Journal of Dermatology 2003, 42, 359-365
A Comparison of the New Filter Ozonometer MICROTOPS II with Dobson and Brewer Spectrometers at Hohenpeissenberg (108K) U. Kohler - Reprint from Geophysical Research Letters
WMO/UNEP Global Ozone Research and Monitoring Project No.3 (782K) Report of WMO's first UV meeting Geneva May 1977
Absolute Measurement and Modelization of 305.5 nm Direct Spectral Solar Radiation in Rosario, Argentina (43K) Work published in Spanish in "Avances en Energias Renovables y Medio Ambiente", Vol. 2, 11.53-11.56 (1998)
UV and Ozone Measurements Provide Meteorological Data
GPS Receiver with Data Cable
Tripod Adapter
NEW field carrying case for the MICROTOPS II
® Ozonometer has just arrived.  It provides excellent protection and toting convenience, perfect if you’re traveling by car, ship, plane, or you’re in the field.  Check out some of the features below:
  • Well padded, durable construction
  • Adjustable shoulder strap
  • Pouch for notepad, pencils, etc.
  • Velcro strap to attach fellow GPS carrying case
MICROTOPS II® is fully operable while inside case.
Included Accessories
Required Accessories

1 year Standard Warranty

SOLAR LIGHT COMPANY warrants that the equipment has been carefully tested, inspected and left the Factory in proper working condition, free of visible defects.  SOLAR LIGHT COMPANY warrants the equipment to be free from defects in material and workmanship, under normal use and operation, for a period of one (1) year after the date of initial operation, or demonstration; or eighteen (18) months from the date of shipment from the Factory; or whichever occurs first. The warranty is limited to the free replacement of all-defective parts and free labor during the first year of warranty.  Defective parts replaced under this warranty shall become the property of SOLAR LIGHT COMPANY. The above stated Warranty is subject to the following conditions: Equipment being installed within the United States of America, Canada, or sold by authorized SOLAR LIGHT COMPANY representatives or their agents outside the continental United States. The equipment being installed is operated and maintained in accordance with SOLAR LIGHT COMPANY’s operating instructions, maintenance instructions and specifications. Utilization of only SOLAR LIGHT COMPANY’s authorized parts and components.  The utilization of a duly authorized representative for all work performed on SOLAR LIGHT COMPANY equipment during the warranty period.  Any variation(s) to the above warranty must be in writing and mutually acceptable by SOLAR LIGHT COMPANY and the customer. The warranty shall not apply to damages resulting from errors in installation, nor shall it apply to any equipment, which has been subject to damages, alterations or misuse by the purchaser.  Parts of the equipment, which would be generally considered as expendable service items during normal use, such as fuses, lamps, detector shields, etc., are not covered under the warranty. THERE ARE NO WARRANTIES, WHICH EXTEND BEYOND THIS DESCRIPTION, AND EXPRESSLY NO IMPLIED WARRANTY OR MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SOLAR LIGHT COMPANY BE LIABLE FOR SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES OR ANTICIPATED LOSS OF PROFITS SUFFERED BY THE PURCHASER.