The present paper presents the results of an experimental investigation of the effect of the shutter unloading coefficient on the energy parameters of a ruby laser. The unloading coefficient is understood to mean the ratio between the radiation densities on the shutter surfaces facing one another and the end surface of the active element. The measurements were carried out for two types of shutters: a shutter made of KS-19 glass and a shutter based on a solution of kryptocyanin in ethanol. The chosen shutters have substantially different spectroscopic parameters. The duration ~- of the excited state for KS-19 glass is 10 -? sec [3 ], while for kryptocyanin it is T ~ 10 -10 sec. The absorption cross section a s at the ruby lasing wavelength is estimated to be ~ 6 �9 10 -19 [3] and 4.10 -16 cm 2 respectively. The majority of other known media for passive shutters haveparameterswh ich fall in the interval between the indicated values. Since ~s is much greater than the absorption cross section of ions in ruby (ar = 2.5.10 -20 cm2), it follows that for Unloading of the shutter one-pulse lasing may be observed within certain limits [4]. The relative optical unloading of the shutter was accomplished by means of a telescopic system. The scattering component of the telescope was a concave spherical surface (R l = 127.6 mm) implemented using the end-face of the active element. A rod having a diameter of 10 mm and a length of the active portion equal to 120 mm was used; its surface was of the matte type. An iris 5 mm in diameter which isolated the uniformly pumped region of the ruby was mounted flush against the spherical surface. The second component of the telescopic system consisted of changeable plane-concave lenses made of K-8 glass which were mounted in optical contact with the shutter made of KS-19 glass or with the window of the vessel if a solution of kryptocyanin was used as the shutter. The lenses used had focal distances of 254, 354, 516, and 685 mm. The resonator was formed by a stack of two glass plates and a dielectric mirror having a reflection coefficient close to unity. The initial transmission of both types of shutter was chosen to be identical and equal to 0.25. The distance between the telescope components at which the lasing energy was maximal was selected for each removable lens, and the duration of the lasing was determined in this portion of the telescopic system. The values of the unloading coefficient of the shutter were 2.5, 5, 10, and 20 in the tests. The pumping was identical and equal to 600 J in all cases.