International Radiation Detectors, Inc.

Uniformity, Spectral Response

Response uniformity of a 10 mm X 10 mm active area IRD photodiode used by NIST as a transfer standard in the 5 nm to 254 nm spectral region is shown in Figure 1. The response uniformity was within ± 0.5% when scanned with a 254 nm photon beam of 1 mm dia. For comparison, Figure 2 shows the uniformity of the UV enhanced diode which NIST currently uses as a transfer standard in the 200 nm to 400 nm spectral range [1]. As seen in Figure 2, the response uniformity of this device was within ± 2%.

Fig. 1: Uniformity of IRD photodiode at 240 nm [1].

Fig. 2: Uniformity tested at 240nm of UV enhanced photodiode used by NIST as a transfer standard for 200nm to 400[1]

The excellent spatial response uniformity of IRD photodiodes will provide better reproducibility than other commercially manufactured photodiodes and therefore exhibit a lower overall measurement uncertainty.

References:

1] Ping-Shine Shaw et. al. "The new ultraviolet spectral responsivity scale based on cryogenic radiometry at Synchrotron Ultraviolet Radiation Facility III"

Rev. of Sci. Instruments, Vol. 72, 2242-2247 (2001)