VCSEL Measurement VCSEL characterization with spectral resolution down to 0.12 nm

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Precise systems for reliable characterization of VCSELs

VCSELs are characterized by excellent beam properties and are thus particularly suitable for critical applications. Typical examples are facial recognition via LiDAR. The use of laser diodes in the presence of humans, however, makes precise characterization of their beam properties essential and presents enormous challenges to the measuring system used.

Based on the high-resolution version of the CAS series of spectroradiometers, Instrument Systems offers a measuring system optimally tuned to VCSEL characterization in the lab. With the appropriate accessories it fulfils diverse individual requirements. Feel free to contact us!

Key Features:

  • Excellent spectral resolution down to 0.12 nm
  • Integration times from 4 ms
  • Array spectroradiometer specially for pulsed laser diodes / VCSELs


Laser diodes typically offer extremely high performance in a very narrow spectral range. Instrument Systems thus offers spectroradiometers with a very high spectral resolution up to 0.1x nm and integration times from 4 ms for the measurement of VCSELs in the lab. An advantage of the traceable absolute calibration of these spectroradiometers is the simple calculation of radiant flux from the measured spectrum. Optionally, the measuring system can be expanded by a photodiode, e.g. for measuring the pulse form of a pulsed laser diode. A dedicated system is available if pulses down to the ns range shall be tested (PVT 110). Please contact us if you have such requirements.

System configuration

An all-in-one system for determining the radiant flux of laser diodes/VCSELs in the lab typically comprises the following components:

Component Description


High-resolution CAS 140CT-HR with up to 0.2 nm spectral resolution as a high-end measurement solution with cooled CCD detector for highest stability, e.g. in a reference system.

High-resolution CAS 120B-HR with up to 0.1x nm spectral resolution as a high performant yet cost-efficient alternative to the CAS 140CT-HR.

Integrating sphere

ISP 75 and ISP 100 with small internal diameter of 75 and 100 mm. The small form factor is particularly suitable for installation in handler and prober systems. 

Optional: ISP 100 with photodiode, e.g. characterization of pulse form with pulsed laser diodes.

Alternative: ISP 150L with 150 mm internal diameter and 50 mm diameter of the measurement port for larger laser modules/arrays and self-absorption correction capability with the aid of an integral auxiliary light source.

Calibration Calibration traceable to national standards as PTB or NIST.


SpecWin Pro laboratory software. CAS.dll and SDK for integration into the customer’s production flow.

IR reference LED (optional)

ACS-570-15, -17: reference LEDs with 860 nm and 950 nm. For stable operation and high precision, it is recommended that it be used in combination with the highly stable PSU-10 power source.

Advice on our systems

Our system experts will be pleased to provide competent advice on your particular application. Just ask us!

Examples of applications