EPC610 datasheet(33/34 Pages) EPC

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4. Optical Design Considerations

This section summarizes some parameters that are of importance when designing the optical system of a TOF imager.

Photosensitive area

The photosensitive area of the sensor is the optical free area which has to be well (full) covered by the illumination optics.

The photosensitive area of the pixel is the relevant surface for calculating the light sensitivity of the chip (pixel).

Note:

Measurement values are reliable only if the object covers the entire photosensitive area of the pixel. Refer to the epc600 Handbook.

Signal sensitivity

The signal sensitivity is defined by the minimum and maximum detectable AC modulation signal (reflected light). It is defined by the light

power (Watt/m2) in relation to:

■ the photo-sensitive area of the pixel.

■ the operating integration time tINT .

■ the operating wavelength λ.

■ the angle of incidence (or reflectance of the sensor surface). Refer to Figure 3.

It is independent of

■ the modulation frequency

Ambient-light suppression

The ability to suppress DC or low-frequency modulation parts of the received light signal. It is defined by the light power (Watt/m 2) in rela-

tion to:

■ the photo-sensitive area of the sensor.

■ the operating integration time tINT.

■ the operating wavelength λ.

■ the angle of interest (or reflectance of the sensor surface). Refer to Figure 3.

Refer also to chapter 1.3.4: Ambient-light suppression.

Operating range

The maximum non-ambiguity distance is < 15m for a modulation frequency of 10MHz @ the pin LED. It is given by the modulation fre-

quency and the time-of-flight.

The operating range (dynamic range) of the epc610 receiver for a certain illumination level is given by the photosensor and its electronics:

■ the AC signal sensitivity for the modulated light.

■ the capability of the ambient-light suppression.

■ the level of illumination.

Depending of the optical design, these ranges do not match. The optical engineer has to plan the optical design and the light power in a

way that matches the application best.

For more detailed information refer to epc's application note AN02 - Reflected power calculation.

Characteristics subject to change without notice

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Datasheet epc610 - V1.7

EPC610 Datasheet(PDF) 33 Page - Espros Photonics corp