Abstract: An apparatus for monitoring the light energy power level of a beam of light, includes beamsplitters on the axis of the light beam for directing portions of the light beam in first and second paths respectively orthogonal to the axis while transmitting the remaining portion of the light beam therethrough. First and second photodetectors having similar spectral responsivity intercept the first and second light beam portions respectively, and detect and signal the light energy power level of the respective first and second light beam portions. Analysis circuitry coupled to the first and second photodetectors and responsive to the output signals therefrom to calculate the total light energy power level of the light beam. The apparatus resolves linearly polarized light into two orthogonal components while permitting most of the light to exit. This exit beam can be analyzed in terms of the incident beam or monitored for measurement or control purposes.

Abstract: A visible spectrum radiation measuring apparatus achieving an absolute measurement utilizing a plurality of inversion layer silicon photodiodes in a configuration wherein light reflected from the surface of a photodiode impinges on another photodiode, and its respective reflected light impinges on another photodiode, such that each time the light impinges on a photodiode surface a portion is absorbed, and that ultimately most of the light of the beam being measured is absorbed.